Merge branch 'master' of ssh://gnunet.org/gnunet

103 files changed, 983 insertions, 483 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index e1d73ab01..16df77fb4 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -28,6 +28,7 @@ if HAVE_MHD
   JSON_DIR = json
 endif
 endif
+if HAVE_MHD
 if HAVE_LIBGNURL
   CURL_DIR = curl
 else
@@ -35,6 +36,7 @@ if HAVE_LIBCURL
   CURL_DIR = curl
 endif
 endif
+endif
 
 if BUILD_PULSE_HELPERS
 CONVERSATION_DIR = conversation
diff --git a/src/abd/gnunet-abd.c b/src/abd/gnunet-abd.c
index a5d32c3dd..eb3e29e23 100644
--- a/src/abd/gnunet-abd.c
+++ b/src/abd/gnunet-abd.c
@@ -1074,7 +1074,7 @@ main (int argc, char *const *argv)
                                        &run,
                                        NULL))
     ret = 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/arm/gnunet-arm.c b/src/arm/gnunet-arm.c
index 3b4e770b0..ea3a012ab 100644
--- a/src/arm/gnunet-arm.c
+++ b/src/arm/gnunet-arm.c
@@ -1054,10 +1054,10 @@ main (int argc, char *const *argv)
          &run,
          NULL)))
   {
-    GNUNET_free ((void *) argv);
+    GNUNET_free_nz ((void *) argv);
     return ret;
   }
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return lret;
 }
 
diff --git a/src/ats-tool/gnunet-ats.c b/src/ats-tool/gnunet-ats.c
index 16636e505..947ed7798 100644
--- a/src/ats-tool/gnunet-ats.c
+++ b/src/ats-tool/gnunet-ats.c
@@ -980,7 +980,7 @@ main (int argc, char *const *argv)
                             NULL);
   GNUNET_free_non_null (opt_pid_str);
   GNUNET_free_non_null (opt_type_str);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
 
   if (GNUNET_OK == res)
     return ret;
diff --git a/src/auction/gnunet-auction-create.c b/src/auction/gnunet-auction-create.c
index 79106d8e8..93947b89c 100644
--- a/src/auction/gnunet-auction-create.c
+++ b/src/auction/gnunet-auction-create.c
@@ -214,6 +214,6 @@ main (int argc, char *const *argv)
                              options,
                              &run,
                              NULL)) ? ret : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
diff --git a/src/auction/gnunet-auction-info.c b/src/auction/gnunet-auction-info.c
index f20565835..dded45ce6 100644
--- a/src/auction/gnunet-auction-info.c
+++ b/src/auction/gnunet-auction-info.c
@@ -78,7 +78,7 @@ main (int argc, char *const *argv)
                              options,
                              &run,
                              NULL)) ? ret : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/auction/gnunet-auction-join.c b/src/auction/gnunet-auction-join.c
index f20565835..dded45ce6 100644
--- a/src/auction/gnunet-auction-join.c
+++ b/src/auction/gnunet-auction-join.c
@@ -78,7 +78,7 @@ main (int argc, char *const *argv)
                              options,
                              &run,
                              NULL)) ? ret : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/cadet/gnunet-cadet.c b/src/cadet/gnunet-cadet.c
index f3ccd9883..9b7538ae7 100644
--- a/src/cadet/gnunet-cadet.c
+++ b/src/cadet/gnunet-cadet.c
@@ -840,7 +840,7 @@ main (int argc, char *const *argv)
                             &run,
                             NULL);
 
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
 
   if (GNUNET_OK == res)
     return 0;
diff --git a/src/conversation/gnunet-conversation-test.c b/src/conversation/gnunet-conversation-test.c
index 2e6772d92..9f8e54033 100644
--- a/src/conversation/gnunet-conversation-test.c
+++ b/src/conversation/gnunet-conversation-test.c
@@ -257,7 +257,7 @@ main (int argc,
                              options,
                              &run,
                              NULL)) ? ret : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/conversation/gnunet-conversation.c b/src/conversation/gnunet-conversation.c
index 6c0a6e42f..b908cd82c 100644
--- a/src/conversation/gnunet-conversation.c
+++ b/src/conversation/gnunet-conversation.c
@@ -1219,7 +1219,7 @@ main (int argc, char *const *argv)
                         options,
                         &run,
                         NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   if (NULL != cfg)
   {
     GNUNET_CONFIGURATION_destroy (cfg);
diff --git a/src/core/gnunet-core.c b/src/core/gnunet-core.c
index 90777a7a8..d90c8e1f5 100644
--- a/src/core/gnunet-core.c
+++ b/src/core/gnunet-core.c
@@ -198,7 +198,7 @@ main (int argc, char *const *argv)
                             &run,
                             NULL);
 
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   if (GNUNET_OK == res)
     return 0;
   return 1;
diff --git a/src/curl/Makefile.am b/src/curl/Makefile.am
index ed5819dee..c6b350bc7 100644
--- a/src/curl/Makefile.am
+++ b/src/curl/Makefile.am
@@ -32,7 +32,7 @@ libgnunetcurl_la_LIBADD = \
   $(LIB_GNURL) \
   $(XLIB)
 libgnunetcurl_la_CPPFLAGS = \
- $(CPP_GNURL) $(AM_CPPFLAGS)
+ $(CPP_GNURL) $(AM_CPPFLAGS) $(MHD_CFLAGS)
 
 #check_PROGRAMS = \
 #  test_curl
diff --git a/src/curl/curl.c b/src/curl/curl.c
index da486ecc1..b7452330f 100644
--- a/src/curl/curl.c
+++ b/src/curl/curl.c
@@ -25,6 +25,7 @@
  */
 #include "platform.h"
 #include <jansson.h>
+#include <microhttpd.h>
 #include "gnunet_curl_lib.h"
 
 #if ENABLE_BENCHMARK
@@ -181,7 +182,8 @@ struct GNUNET_CURL_Context
  * @return library context
  */
 struct GNUNET_CURL_Context *
-GNUNET_CURL_init (GNUNET_CURL_RescheduleCallback cb, void *cb_cls)
+GNUNET_CURL_init (GNUNET_CURL_RescheduleCallback cb,
+                  void *cb_cls)
 {
   struct GNUNET_CURL_Context *ctx;
   CURLM *multi;
@@ -263,7 +265,10 @@ GNUNET_CURL_is_valid_scope_id (const char *scope_id)
  * @return number of bytes processed from @a bufptr
  */
 static size_t
-download_cb (char *bufptr, size_t size, size_t nitems, void *cls)
+download_cb (char *bufptr,
+             size_t size,
+             size_t nitems,
+             void *cls)
 {
   struct GNUNET_CURL_DownloadBuffer *db = cls;
   size_t msize;
@@ -376,7 +381,9 @@ setup_job (CURL *eh,
   }
   job->easy_handle = eh;
   job->ctx = ctx;
-  GNUNET_CONTAINER_DLL_insert (ctx->jobs_head, ctx->jobs_tail, job);
+  GNUNET_CONTAINER_DLL_insert (ctx->jobs_head,
+                               ctx->jobs_tail,
+                               job);
   return job;
 }
 
@@ -497,7 +504,11 @@ GNUNET_CURL_job_add (struct GNUNET_CURL_Context *ctx,
                  curl_slist_append (NULL, "Content-Type: application/json")));
   }
 
-  job = GNUNET_CURL_job_add2 (ctx, eh, job_headers, jcc, jcc_cls);
+  job = GNUNET_CURL_job_add2 (ctx,
+                              eh,
+                              job_headers,
+                              jcc,
+                              jcc_cls);
   curl_slist_free_all (job_headers);
   return job;
 }
@@ -526,6 +537,40 @@ GNUNET_CURL_job_cancel (struct GNUNET_CURL_Job *job)
 
 
 /**
+ * Test if the given content type @a ct is JSON
+ *
+ * @param ct a content type, i.e. "application/json; charset=UTF-8"
+ * @return true if @a ct denotes JSON
+ */
+static bool
+is_json (const char *ct)
+{
+  const char *semi;
+
+  /* check for "application/json" exact match */
+  if (0 == strcasecmp (ct,
+                       "application/json"))
+    return true;
+  /* check for "application/json;[ANYTHING]" */
+  semi = strchr (ct,
+                 ';');
+  /* also allow "application/json [ANYTHING]" (note the space!) */
+  if (NULL == semi)
+    semi = strchr (ct,
+                   ' ');
+  if (NULL == semi)
+    return false; /* no delimiter we accept, forget it */
+  if (semi - ct != strlen ("application/json"))
+    return false; /* delimiter past desired length, forget it */
+  if (0 == strncasecmp (ct,
+                        "application/json",
+                        strlen ("application/json")))
+    return true; /* OK */
+  return false;
+}
+
+
+/**
  * Obtain information about the final result about the
  * HTTP download. If the download was successful, parses
  * the JSON in the @a db and returns it. Also returns
@@ -562,8 +607,7 @@ GNUNET_CURL_download_get_result_ (struct GNUNET_CURL_DownloadBuffer *db,
                           CURLINFO_CONTENT_TYPE,
                           &ct)) ||
       (NULL == ct) ||
-      (0 != strcasecmp (ct,
-                        "application/json")))
+      (! is_json (ct)))
   {
     /* No content type or explicitly not JSON, refuse to parse
        (but keep response code) */
@@ -583,6 +627,8 @@ GNUNET_CURL_download_get_result_ (struct GNUNET_CURL_DownloadBuffer *db,
                   (const char *) db->buf);
     return NULL;
   }
+  if (MHD_HTTP_NO_CONTENT == *response_code)
+    return NULL;
   json = NULL;
   if (0 == db->eno)
   {
diff --git a/src/datastore/gnunet-datastore.c b/src/datastore/gnunet-datastore.c
index 54d087bc4..5901cce54 100644
--- a/src/datastore/gnunet-datastore.c
+++ b/src/datastore/gnunet-datastore.c
@@ -500,7 +500,7 @@ main (int argc, char *const *argv)
                           &run,
                           NULL))
     ret = 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/dns/gnunet-dns-monitor.c b/src/dns/gnunet-dns-monitor.c
index 7be792fc5..f6c0d0660 100644
--- a/src/dns/gnunet-dns-monitor.c
+++ b/src/dns/gnunet-dns-monitor.c
@@ -387,7 +387,7 @@ main (int argc, char *const *argv)
                              gettext_noop
                                ("Monitor DNS queries."), options,
                              &run, NULL)) ? ret : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/dns/gnunet-dns-redirector.c b/src/dns/gnunet-dns-redirector.c
index f7051f70b..606864c8a 100644
--- a/src/dns/gnunet-dns-redirector.c
+++ b/src/dns/gnunet-dns-redirector.c
@@ -260,7 +260,7 @@ main (int argc, char *const *argv)
                                ("Change DNS replies to point elsewhere."),
                              options,
                              &run, NULL)) ? ret : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/fs/gnunet-auto-share.c b/src/fs/gnunet-auto-share.c
index 53c64ab04..13bc908e8 100644
--- a/src/fs/gnunet-auto-share.c
+++ b/src/fs/gnunet-auto-share.c
@@ -775,7 +775,7 @@ main (int argc, char *const *argv)
   sigpipe = NULL;
   GNUNET_free_non_null (cfg_filename);
   cfg_filename = NULL;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ok;
 }
 
diff --git a/src/fs/gnunet-directory.c b/src/fs/gnunet-directory.c
index 58950bceb..10a09f73b 100644
--- a/src/fs/gnunet-directory.c
+++ b/src/fs/gnunet-directory.c
@@ -203,7 +203,7 @@ main (int argc, char *const *argv)
                              NULL))
         ? ret
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/fs/gnunet-download.c b/src/fs/gnunet-download.c
index 63bb02958..eebf8e993 100644
--- a/src/fs/gnunet-download.c
+++ b/src/fs/gnunet-download.c
@@ -376,7 +376,7 @@ main (int argc, char *const *argv)
        NULL))
     ? ret
     : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/fs/gnunet-fs-profiler.c b/src/fs/gnunet-fs-profiler.c
index fe86cf21f..62da46834 100644
--- a/src/fs/gnunet-fs-profiler.c
+++ b/src/fs/gnunet-fs-profiler.c
@@ -237,7 +237,7 @@ main (int argc, char *const *argv)
                                "run a testbed to measure file-sharing performance"),
                              options, &run,
                              NULL)) ? ret : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/fs/gnunet-fs.c b/src/fs/gnunet-fs.c
index 35d410d37..70a0034a0 100644
--- a/src/fs/gnunet-fs.c
+++ b/src/fs/gnunet-fs.c
@@ -144,7 +144,7 @@ main (int argc, char *const *argv)
                              NULL))
         ? ret
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/fs/gnunet-publish.c b/src/fs/gnunet-publish.c
index ac310b785..b10e6163c 100644
--- a/src/fs/gnunet-publish.c
+++ b/src/fs/gnunet-publish.c
@@ -992,7 +992,7 @@ main (int argc, char *const *argv)
                          NULL))
     ? ret
     : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/fs/gnunet-search.c b/src/fs/gnunet-search.c
index e0b9a31fd..098633379 100644
--- a/src/fs/gnunet-search.c
+++ b/src/fs/gnunet-search.c
@@ -371,7 +371,7 @@ main (int argc, char *const *argv)
                          NULL))
     ? ret
     : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/fs/gnunet-unindex.c b/src/fs/gnunet-unindex.c
index bf32de812..afc547127 100644
--- a/src/fs/gnunet-unindex.c
+++ b/src/fs/gnunet-unindex.c
@@ -197,7 +197,7 @@ main (int argc, char *const *argv)
            NULL))
         ? ret
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/gns/gnunet-bcd.c b/src/gns/gnunet-bcd.c
index 6ceff4a9a..f71f477ef 100644
--- a/src/gns/gnunet-bcd.c
+++ b/src/gns/gnunet-bcd.c
@@ -525,7 +525,7 @@ main (int argc, char *const *argv)
                              NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/gns/gnunet-dns2gns.c b/src/gns/gnunet-dns2gns.c
index 8ec1f1cdb..eb9996b36 100644
--- a/src/gns/gnunet-dns2gns.c
+++ b/src/gns/gnunet-dns2gns.c
@@ -775,7 +775,7 @@ main (int argc,
                          _ ("GNUnet DNS-to-GNS proxy (a DNS server)"),
                          options,
                          &run, NULL)) ? 0 : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/gns/gnunet-gns-benchmark.c b/src/gns/gnunet-gns-benchmark.c
index 0dcff7566..b36a83f21 100644
--- a/src/gns/gnunet-gns-benchmark.c
+++ b/src/gns/gnunet-gns-benchmark.c
@@ -610,7 +610,7 @@ main (int argc,
                           &run,
                           NULL))
     ret = 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/gns/gnunet-gns-import.c b/src/gns/gnunet-gns-import.c
index 0c104ee0d..2c7c56411 100644
--- a/src/gns/gnunet-gns-import.c
+++ b/src/gns/gnunet-gns-import.c
@@ -486,7 +486,7 @@ main (int argc, char *const *argv)
                             "This program will import some GNS authorities into your GNS namestore."),
                           options,
                           &run, NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return GNUNET_OK == r ? ret : 1;
 }
 
diff --git a/src/gns/gnunet-gns.c b/src/gns/gnunet-gns.c
index d52761ef8..eb1d4f23f 100644
--- a/src/gns/gnunet-gns.c
+++ b/src/gns/gnunet-gns.c
@@ -376,7 +376,7 @@ main (int argc, char *const *argv)
                             options,
                             &run,
                             NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   if (GNUNET_OK != ret)
     return 1;
   return global_ret;
diff --git a/src/gnsrecord/perf_gnsrecord_crypto.c b/src/gnsrecord/perf_gnsrecord_crypto.c
index b2614eb77..eb4633f75 100644
--- a/src/gnsrecord/perf_gnsrecord_crypto.c
+++ b/src/gnsrecord/perf_gnsrecord_crypto.c
@@ -107,7 +107,7 @@ run (void *cls,
              GNUNET_YES),
            ROUNDS);
   for (unsigned int i = 0; i < RECORDS; i++)
-    GNUNET_free ((void *) s_rd[i].data);
+    GNUNET_free_nz ((void *) s_rd[i].data);
   GNUNET_free (s_rd);
 }
 
diff --git a/src/gnsrecord/test_gnsrecord_serialization.c b/src/gnsrecord/test_gnsrecord_serialization.c
index 22d9f8396..d268cb7f3 100644
--- a/src/gnsrecord/test_gnsrecord_serialization.c
+++ b/src/gnsrecord/test_gnsrecord_serialization.c
@@ -132,7 +132,7 @@ run (void *cls,
 
   for (c = 0; c < rd_count; c++)
   {
-    GNUNET_free ((void *) src[c].data);
+    GNUNET_free_nz ((void *) src[c].data);
   }
 }
 
diff --git a/src/hostlist/gnunet-daemon-hostlist.c b/src/hostlist/gnunet-daemon-hostlist.c
index ca77545cd..704c796b4 100644
--- a/src/hostlist/gnunet-daemon-hostlist.c
+++ b/src/hostlist/gnunet-daemon-hostlist.c
@@ -409,7 +409,7 @@ main (int argc, char *const *argv)
                          _ ("GNUnet hostlist server and client"),
                          options,
                          &run, NULL)) ? 0 : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/identity/gnunet-identity.c b/src/identity/gnunet-identity.c
index 1350376d9..8445a0ee5 100644
--- a/src/identity/gnunet-identity.c
+++ b/src/identity/gnunet-identity.c
@@ -439,7 +439,7 @@ main (int argc, char *const *argv)
                             options,
                             &run,
                             NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
 
   if (GNUNET_OK != res)
     return 3;
diff --git a/src/include/gnunet_common.h b/src/include/gnunet_common.h
index 78aeb3de7..033a68894 100644
--- a/src/include/gnunet_common.h
+++ b/src/include/gnunet_common.h
@@ -1209,7 +1209,10 @@ GNUNET_is_zero_ (const void *a,
  * @param n number of elements in the array
  * @param type name of the struct or union, i.e. pass 'struct Foo'.
  */
-#define GNUNET_new_array(n, type) (type *) GNUNET_malloc ((n) * sizeof(type))
+#define GNUNET_new_array(n, type) ({ \
+    GNUNET_assert (SIZE_MAX / sizeof (type) >= n); \
+    (type *) GNUNET_malloc ((n) * sizeof(type));   \
+  })
 
 /**
  * @ingroup memory
@@ -1284,23 +1287,23 @@ GNUNET_is_zero_ (const void *a,
  * @ingroup memory
  * Wrapper around free. Frees the memory referred to by ptr.
  * Note that it is generally better to free memory that was
- * allocated with #GNUNET_array_grow using #GNUNET_array_grow(mem, size, 0) instead of #GNUNET_free.
+ * allocated with #GNUNET_array_grow using #GNUNET_array_grow(mem, size, 0) instead of #GNUNET_free_nz.
  *
  * @param ptr location where to free the memory. ptr must have
  *     been returned by #GNUNET_strdup, #GNUNET_strndup, #GNUNET_malloc or #GNUNET_array_grow earlier.
  */
-#define GNUNET_free(ptr) GNUNET_xfree_ (ptr, __FILE__, __LINE__)
+#define GNUNET_free_nz(ptr) GNUNET_xfree_ (ptr, __FILE__, __LINE__)
 
 /**
  * @ingroup memory
  * Wrapper around free. Frees the memory referred to by ptr and sets ptr to NULL.
  * Note that it is generally better to free memory that was
- * allocated with #GNUNET_array_grow using #GNUNET_array_grow(mem, size, 0) instead of #GNUNET_freez.
+ * allocated with #GNUNET_array_grow using #GNUNET_array_grow(mem, size, 0) instead of #GNUNET_free.
  *
  * @param ptr location where to free the memory. ptr must have
  *     been returned by #GNUNET_strdup, #GNUNET_strndup, #GNUNET_malloc or #GNUNET_array_grow earlier.
  */
-#define GNUNET_freez(ptr) do { \
+#define GNUNET_free(ptr) do { \
     GNUNET_xfree_ (ptr, __FILE__, __LINE__); \
     ptr = NULL; \
 } while (0)
@@ -1389,22 +1392,58 @@ GNUNET_is_zero_ (const void *a,
 
 /**
  * @ingroup memory
- * Append an element to a list (growing the list by one).
+ * Append an element to an array (growing the array by one).
  *
- * @param arr base-pointer of the vector, may be NULL if size is 0;
+ * @param arr base-pointer of the vector, may be NULL if @a len is 0;
  *        will be updated to reflect the new address. The TYPE of
  *        arr is important since size is the number of elements and
  *        not the size in bytes
- * @param size the number of elements in the existing vector (number
+ * @param len the number of elements in the existing vector (number
  *        of elements to copy over), will be updated with the new
- *        array size
+ *        array length
  * @param element the element that will be appended to the array
  */
-#define GNUNET_array_append(arr, size, element) \
+#define GNUNET_array_append(arr, len, element) \
+  do                                            \
+  {                                             \
+    GNUNET_assert ((len) + 1 > (len)); \
+    GNUNET_array_grow (arr, len, len + 1);    \
+    (arr) [len - 1] = element;                  \
+  } while (0)
+
+
+/**
+ * @ingroup memory
+ * Append @a arr2 to @a arr1 (growing @a arr1
+ * as needed).  The @a arr2 array is left unchanged. Naturally
+ * this function performs a shallow copy. Both arrays must have
+ * the same type for their elements.
+ *
+ * @param arr1 base-pointer of the vector, may be NULL if @a len is 0;
+ *        will be updated to reflect the new address. The TYPE of
+ *        arr is important since size is the number of elements and
+ *        not the size in bytes
+ * @param len1 the number of elements in the existing vector (number
+ *        of elements to copy over), will be updated with the new
+ *        array size
+ * @param arr2 base-pointer a second array to concatenate, may be NULL if @a len2 is 0;
+ *        will be updated to reflect the new address. The TYPE of
+ *        arr is important since size is the number of elements and
+ *        not the size in bytes
+ * @param len the number of elements in the existing vector (number
+ *        of elements to copy over), will be updated with the new
+ *        array size
+
+ */
+#define GNUNET_array_concatenate(arr1, len1, arr2, len2)   \
   do                                            \
   {                                             \
-    GNUNET_array_grow (arr, size, size + 1);    \
-    (arr) [size - 1] = element;                  \
+    const typeof (*arr2) * _a1 = (arr1);  \
+    const typeof (*arr1) * _a2 = (arr2);  \
+    GNUNET_assert ((len1) + (len2) >= (len1));                    \
+    GNUNET_assert (SIZE_MAX / sizeof (*_a1) >= ((len1) + (len2))); \
+    GNUNET_array_grow (arr1, len1, (len1) + (len2));            \
+    memcpy (&(arr1) [(len1) - (len2)], _a2, (len2) * sizeof (*arr1));    \
   } while (0)
 
 /**
diff --git a/src/include/gnunet_json_lib.h b/src/include/gnunet_json_lib.h
index f6cabd589..27996f18d 100644
--- a/src/include/gnunet_json_lib.h
+++ b/src/include/gnunet_json_lib.h
@@ -219,6 +219,17 @@ GNUNET_JSON_spec_json (const char *name, json_t **jsonp);
 
 
 /**
+ * boolean.
+ *
+ * @param name name of the JSON field
+ * @param[out] b where to store the boolean found under @a name
+ */
+struct GNUNET_JSON_Specification
+GNUNET_JSON_spec_bool (const char *name,
+                       bool *b);
+
+
+/**
  * 8-bit integer.
  *
  * @param name name of the JSON field
diff --git a/src/include/gnunet_revocation_service.h b/src/include/gnunet_revocation_service.h
index 7222cedc1..9a8918b43 100644
--- a/src/include/gnunet_revocation_service.h
+++ b/src/include/gnunet_revocation_service.h
@@ -51,6 +51,73 @@ extern "C"
 #define GNUNET_REVOCATION_VERSION 0x00000000
 
 /**
+ * The proof-of-work narrowing factor.
+ * The number of PoWs that are calculates as part of revocation.
+ */
+#define POW_COUNT 32
+
+
+GNUNET_NETWORK_STRUCT_BEGIN
+
+struct GNUNET_REVOCATION_Pow
+{
+  /**
+   * The timestamp of the revocation
+   */
+  struct GNUNET_TIME_AbsoluteNBO timestamp;
+
+  /**
+   * The TTL of this revocation (purely informational)
+   */
+  struct GNUNET_TIME_RelativeNBO ttl;
+
+  /**
+   * The PoWs
+   */
+  uint64_t pow[POW_COUNT] GNUNET_PACKED;
+
+  /**
+   * The signature
+   */
+  struct GNUNET_CRYPTO_EcdsaSignature signature;
+
+  /**
+   * The revoked public key
+   */
+  struct GNUNET_CRYPTO_EcdsaPublicKey key;
+};
+
+
+/**
+ * The signature object we use for the PoW
+ */
+struct GNUNET_REVOCATION_SignaturePurpose
+{
+  /**
+   * The signature purpose
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+  /**
+   * The revoked public key
+   */
+  struct GNUNET_CRYPTO_EcdsaPublicKey key;
+
+  /**
+   * The timestamp of the revocation
+   */
+  struct GNUNET_TIME_AbsoluteNBO timestamp;
+};
+
+GNUNET_NETWORK_STRUCT_END
+
+
+/**
+ * Handle to a running proof-of-work calculation.
+ */
+struct GNUNET_REVOCATION_PowCalculationHandle;
+
+/**
  * Handle for the key revocation query.
  */
 struct GNUNET_REVOCATION_Query;
@@ -65,7 +132,8 @@ struct GNUNET_REVOCATION_Query;
  *
  */
 typedef void (*GNUNET_REVOCATION_Callback) (void *cls,
-                                            int is_valid);
+                                            enum GNUNET_GenericReturnValue
+                                            is_valid);
 
 
 /**
@@ -102,12 +170,9 @@ struct GNUNET_REVOCATION_Handle;
  * Perform key revocation.
  *
  * @param cfg the configuration to use
- * @param key public key of the key to revoke
- * @param sig signature to use on the revocation (should have been
- *            created using #GNUNET_REVOCATION_sign_revocation).
  * @param pow proof of work to use (should have been created by
- *            iteratively calling #GNUNET_REVOCATION_check_pow)
- * @param func funtion to call with the result of the check
+ *            iteratively calling #GNUNET_REVOCATION_pow_round)
+ * @param func function to call with the result of the check
  *             (called with `is_valid` being #GNUNET_NO if
  *              the revocation worked).
  * @param func_cls closure to pass to @a func
@@ -115,9 +180,7 @@ struct GNUNET_REVOCATION_Handle;
  */
 struct GNUNET_REVOCATION_Handle *
 GNUNET_REVOCATION_revoke (const struct GNUNET_CONFIGURATION_Handle *cfg,
-                          const struct GNUNET_CRYPTO_EcdsaPublicKey *key,
-                          const struct GNUNET_CRYPTO_EcdsaSignature *sig,
-                          uint64_t pow,
+                          const struct GNUNET_REVOCATION_Pow *pow,
                           GNUNET_REVOCATION_Callback func, void *func_cls);
 
 
@@ -131,31 +194,64 @@ GNUNET_REVOCATION_revoke_cancel (struct GNUNET_REVOCATION_Handle *h);
 
 
 /**
- * Check if the given proof-of-work value
- * would be acceptable for revoking the given key.
+ * Check if the given proof-of-work is valid.
  *
- * @param key key to check for
- * @param pow proof of work value
+ * @param pow proof of work
  * @param matching_bits how many bits must match (configuration)
+ * @param epoch_duration length of single epoch in configuration
  * @return #GNUNET_YES if the @a pow is acceptable, #GNUNET_NO if not
  */
-int
-GNUNET_REVOCATION_check_pow (const struct GNUNET_CRYPTO_EcdsaPublicKey *key,
-                             uint64_t pow,
-                             unsigned int matching_bits);
+enum GNUNET_GenericReturnValue
+GNUNET_REVOCATION_check_pow (const struct GNUNET_REVOCATION_Pow *pow,
+                             unsigned int matching_bits,
+                             struct GNUNET_TIME_Relative epoch_duration);
 
 
 /**
- * Create a revocation signature.
+ * Initializes a fresh PoW computation.
  *
- * @param key private key of the key to revoke
- * @param sig where to write the revocation signature
+ * @param key the key to calculate the PoW for.
+ * @param pow the pow object to work with in the calculation.
  */
 void
-GNUNET_REVOCATION_sign_revocation (const struct
-                                   GNUNET_CRYPTO_EcdsaPrivateKey *key,
-                                   struct GNUNET_CRYPTO_EcdsaSignature *sig);
+GNUNET_REVOCATION_pow_init (const struct GNUNET_CRYPTO_EcdsaPrivateKey *key,
+                            struct GNUNET_REVOCATION_Pow *pow);
+
+
+/**
+ * Starts a proof-of-work calculation given the pow object as well as
+ * target epochs and difficulty.
+ *
+ * @param pow the PoW to based calculations on.
+ * @param epochs the number of epochs for which the PoW must be valid.
+ * @param difficulty the base difficulty of the PoW.
+ * @return a handle for use in PoW rounds
+ */
+struct GNUNET_REVOCATION_PowCalculationHandle*
+GNUNET_REVOCATION_pow_start (struct GNUNET_REVOCATION_Pow *pow,
+                             int epochs,
+                             unsigned int difficulty);
+
 
+/**
+ * Calculate a single round in the key revocation PoW.
+ *
+ * @param pc handle to the PoW, initially called with NULL.
+ * @return GNUNET_YES if the @a pow is acceptable, GNUNET_NO if not
+ */
+enum GNUNET_GenericReturnValue
+GNUNET_REVOCATION_pow_round (struct GNUNET_REVOCATION_PowCalculationHandle *pc);
+
+
+/**
+ * Stop a PoW calculation
+ *
+ * @param pc the calculation to clean up
+ * @return #GNUNET_YES if pow valid, #GNUNET_NO if pow was set but is not
+ * valid
+ */
+void
+GNUNET_REVOCATION_pow_stop (struct GNUNET_REVOCATION_PowCalculationHandle *pc);
 
 #if 0                           /* keep Emacsens' auto-indent happy */
 {
diff --git a/src/json/Makefile.am b/src/json/Makefile.am
index 5968a3596..9cd80851c 100644
--- a/src/json/Makefile.am
+++ b/src/json/Makefile.am
@@ -37,6 +37,7 @@ TESTS = \
 
 test_json_SOURCES = \
   test_json.c
+test_json_CFLAGS = $(MHD_CFLAGS) $(AM_CFLAGS)
 test_json_LDADD = \
   libgnunetjson.la \
   $(top_builddir)/src/util/libgnunetutil.la \
diff --git a/src/json/json_gnsrecord.c b/src/json/json_gnsrecord.c
index bfbdd96ee..37f0c03da 100644
--- a/src/json/json_gnsrecord.c
+++ b/src/json/json_gnsrecord.c
@@ -50,10 +50,10 @@ cleanup_recordinfo (struct GnsRecordInfo *gnsrecord_info)
 {
   if (NULL != *(gnsrecord_info->rd))
   {
-    for (int i = 0; i < *(gnsrecord_info->rd_count); i++)
+    for (unsigned int i = 0; i < *(gnsrecord_info->rd_count); i++)
     {
       if (NULL != (*(gnsrecord_info->rd))[i].data)
-        GNUNET_free ((char *) (*(gnsrecord_info->rd))[i].data);
+        GNUNET_free_nz ((char *) (*(gnsrecord_info->rd))[i].data);
     }
     GNUNET_free (*(gnsrecord_info->rd));
     *(gnsrecord_info->rd) = NULL;
diff --git a/src/json/json_helper.c b/src/json/json_helper.c
index 74a92ce9f..02bd6bfab 100644
--- a/src/json/json_helper.c
+++ b/src/json/json_helper.c
@@ -327,6 +327,60 @@ GNUNET_JSON_spec_json (const char *name,
 
 
 /**
+ * Parse given JSON object to a bool.
+ *
+ * @param cls closure, NULL
+ * @param root the json object representing data
+ * @param[out] spec where to write the data
+ * @return #GNUNET_OK upon successful parsing; #GNUNET_SYSERR upon error
+ */
+static int
+parse_bool (void *cls,
+            json_t *root,
+            struct GNUNET_JSON_Specification *spec)
+{
+  bool *b = spec->ptr;
+
+  if (json_true () == root)
+  {
+    *b = true;
+    return GNUNET_OK;
+  }
+  if (json_false () == root)
+  {
+    *b = false;
+    return GNUNET_OK;
+  }
+  GNUNET_break_op (0);
+  return GNUNET_SYSERR;
+}
+
+
+/**
+ * boolean.
+ *
+ * @param name name of the JSON field
+ * @param[out] b where to store the boolean found under @a name
+ */
+struct GNUNET_JSON_Specification
+GNUNET_JSON_spec_bool (const char *name,
+                       bool *b)
+{
+  struct GNUNET_JSON_Specification ret = {
+    .parser = &parse_bool,
+    .cleaner = NULL,
+    .cls = NULL,
+    .field = name,
+    .ptr = b,
+    .ptr_size = sizeof(bool),
+    .size_ptr = NULL
+  };
+
+  return ret;
+}
+
+
+/**
  * Parse given JSON object to a uint8_t.
  *
  * @param cls closure, NULL
diff --git a/src/json/test_json_mhd.c b/src/json/test_json_mhd.c
index 5ab1b63ca..642715f25 100644
--- a/src/json/test_json_mhd.c
+++ b/src/json/test_json_mhd.c
@@ -27,6 +27,7 @@
 #include "gnunet_util_lib.h"
 #include "gnunet_json_lib.h"
 #include "gnunet_curl_lib.h"
+#include "gnunet_mhd_compat.h"
 #include <zlib.h>
 
 #define MAX_SIZE 1024 * 1024
@@ -36,7 +37,7 @@ static json_t *bigj;
 static int global_ret;
 
 
-static int
+static MHD_RESULT
 access_handler_cb (void *cls,
                    struct MHD_Connection *connection,
                    const char *url,
diff --git a/src/namecache/gnunet-namecache.c b/src/namecache/gnunet-namecache.c
index 15a0c96ee..2e3c733e6 100644
--- a/src/namecache/gnunet-namecache.c
+++ b/src/namecache/gnunet-namecache.c
@@ -235,10 +235,10 @@ main (int argc, char *const *argv)
                                        &run,
                                        NULL))
   {
-    GNUNET_free ((void *) argv);
+    GNUNET_free_nz ((void *) argv);
     return 1;
   }
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/namecache/test_namecache_api_cache_block.c b/src/namecache/test_namecache_api_cache_block.c
index 9b150c9d9..12b72d93b 100644
--- a/src/namecache/test_namecache_api_cache_block.c
+++ b/src/namecache/test_namecache_api_cache_block.c
@@ -39,7 +39,7 @@ static struct GNUNET_NAMECACHE_Handle *nsh;
 
 static struct GNUNET_SCHEDULER_Task *endbadly_task;
 
-static struct GNUNET_CRYPTO_EcdsaPrivateKey *privkey;
+static struct GNUNET_CRYPTO_EcdsaPrivateKey privkey;
 
 static struct GNUNET_CRYPTO_EcdsaPublicKey pubkey;
 
@@ -56,11 +56,6 @@ cleanup ()
     GNUNET_NAMECACHE_disconnect (nsh);
     nsh = NULL;
   }
-  if (NULL != privkey)
-  {
-    GNUNET_free (privkey);
-    privkey = NULL;
-  }
   GNUNET_SCHEDULER_shutdown ();
 }
 
@@ -188,10 +183,12 @@ run (void *cls,
                    "N0UJMP015AFUNR2BTNM3FKPBLG38913BL8IDMCO2H0A1LIB81960.zkey");
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Using zonekey file `%s' \n",
               hostkey_file);
-  privkey = GNUNET_CRYPTO_ecdsa_key_create_from_file (hostkey_file);
+  GNUNET_assert (GNUNET_SYSERR !=
+                 GNUNET_CRYPTO_ecdsa_key_from_file (hostkey_file,
+                                                    GNUNET_YES,
+                                                    &privkey));
   GNUNET_free (hostkey_file);
-  GNUNET_assert (privkey != NULL);
-  GNUNET_CRYPTO_ecdsa_key_get_public (privkey, &pubkey);
+  GNUNET_CRYPTO_ecdsa_key_get_public (&privkey, &pubkey);
 
 
   rd.expiration_time = GNUNET_TIME_absolute_get ().abs_value_us + 10000000000;
@@ -200,7 +197,7 @@ run (void *cls,
   rd.data = GNUNET_malloc (TEST_RECORD_DATALEN);
   rd.flags = 0;
   memset ((char *) rd.data, 'a', TEST_RECORD_DATALEN);
-  block = GNUNET_GNSRECORD_block_create (privkey,
+  block = GNUNET_GNSRECORD_block_create (&privkey,
                                          GNUNET_TIME_UNIT_FOREVER_ABS,
                                          name, &rd, 1);
   if (NULL == block)
@@ -232,7 +229,7 @@ run (void *cls,
                 _ ("Namecache cannot cache no block\n"));
   }
   GNUNET_free (block);
-  GNUNET_free ((void *) rd.data);
+  GNUNET_free_nz ((void *) rd.data);
 }
 
 
diff --git a/src/namestore/gnunet-namestore-fcfsd.c b/src/namestore/gnunet-namestore-fcfsd.c
index 67fc5bdf4..34641d22e 100644
--- a/src/namestore/gnunet-namestore-fcfsd.c
+++ b/src/namestore/gnunet-namestore-fcfsd.c
@@ -1210,7 +1210,7 @@ main (int argc,
                            "GNU Name System First Come First Serve name registration service"),
                          options,
                          &run, NULL)) ? 0 : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   GNUNET_CRYPTO_ecdsa_key_clear (&fcfs_zone_pkey);
   return ret;
 }
diff --git a/src/namestore/gnunet-namestore.c b/src/namestore/gnunet-namestore.c
index 25dfda59b..508566a49 100644
--- a/src/namestore/gnunet-namestore.c
+++ b/src/namestore/gnunet-namestore.c
@@ -1688,11 +1688,11 @@ main (int argc, char *const *argv)
                                   &run,
                                   NULL)))
   {
-    GNUNET_free ((void *) argv);
+    GNUNET_free_nz ((void *) argv);
     GNUNET_CRYPTO_ecdsa_key_clear (&zone_pkey);
     return lret;
   }
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   GNUNET_CRYPTO_ecdsa_key_clear (&zone_pkey);
   return ret;
 }
diff --git a/src/namestore/gnunet-zoneimport.c b/src/namestore/gnunet-zoneimport.c
index eca02bdc3..5b4e41475 100644
--- a/src/namestore/gnunet-zoneimport.c
+++ b/src/namestore/gnunet-zoneimport.c
@@ -1866,7 +1866,7 @@ main (int argc, char *const *argv)
                                               &run,
                                               NULL)))
     return ret;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   fprintf (stderr,
            "Rejected %u names, had %u cached, did %u lookups, stored %u record sets\n"
            "Found %u records, %u lookups failed, %u/%u pending on shutdown\n",
diff --git a/src/namestore/plugin_rest_namestore.c b/src/namestore/plugin_rest_namestore.c
index d2a93a286..c0bf4b048 100644
--- a/src/namestore/plugin_rest_namestore.c
+++ b/src/namestore/plugin_rest_namestore.c
@@ -267,7 +267,7 @@ cleanup_handle (void *cls)
     for (int i = 0; i < handle->rd_count; i++)
     {
       if (NULL != handle->rd[i].data)
-        GNUNET_free ((void *) handle->rd[i].data);
+        GNUNET_free_nz ((void *) handle->rd[i].data);
     }
     GNUNET_free (handle->rd);
   }
diff --git a/src/namestore/test_namestore_api_lookup_private.c b/src/namestore/test_namestore_api_lookup_private.c
index 98fdb1b43..d0ad726cc 100644
--- a/src/namestore/test_namestore_api_lookup_private.c
+++ b/src/namestore/test_namestore_api_lookup_private.c
@@ -212,7 +212,7 @@ run (void *cls,
                 _ ("Namestore cannot store no block\n"));
   }
 
-  GNUNET_free ((void *) rd.data);
+  GNUNET_free_nz ((void *) rd.data);
 }
 
 
diff --git a/src/namestore/test_namestore_api_lookup_public.c b/src/namestore/test_namestore_api_lookup_public.c
index 83a5a78f6..039c7cbf6 100644
--- a/src/namestore/test_namestore_api_lookup_public.c
+++ b/src/namestore/test_namestore_api_lookup_public.c
@@ -221,7 +221,7 @@ run (void *cls,
                 _ ("Namestore cannot store no block\n"));
   }
 
-  GNUNET_free ((void *) rd.data);
+  GNUNET_free_nz ((void *) rd.data);
 }
 
 
diff --git a/src/namestore/test_namestore_api_lookup_shadow.c b/src/namestore/test_namestore_api_lookup_shadow.c
index 08c428731..d399d903a 100644
--- a/src/namestore/test_namestore_api_lookup_shadow.c
+++ b/src/namestore/test_namestore_api_lookup_shadow.c
@@ -254,7 +254,7 @@ run (void *cls,
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 _ ("Namestore cannot store no block\n"));
   }
-  GNUNET_free ((void *) rd.data);
+  GNUNET_free_nz ((void *) rd.data);
 }
 
 
diff --git a/src/namestore/test_namestore_api_lookup_shadow_filter.c b/src/namestore/test_namestore_api_lookup_shadow_filter.c
index 634a6a3c4..40dbeb90f 100644
--- a/src/namestore/test_namestore_api_lookup_shadow_filter.c
+++ b/src/namestore/test_namestore_api_lookup_shadow_filter.c
@@ -336,8 +336,8 @@ run (void *cls,
                 _ ("Namestore cannot store no block\n"));
   }
 
-  GNUNET_free ((void *) records[0].data);
-  GNUNET_free ((void *) records[1].data);
+  GNUNET_free_nz ((void *) records[0].data);
+  GNUNET_free_nz ((void *) records[1].data);
 }
 
 
diff --git a/src/namestore/test_namestore_api_monitoring.c b/src/namestore/test_namestore_api_monitoring.c
index d26492517..cc00adf44 100644
--- a/src/namestore/test_namestore_api_monitoring.c
+++ b/src/namestore/test_namestore_api_monitoring.c
@@ -94,17 +94,17 @@ do_shutdown ()
 
   if (s_rd_1 != NULL)
   {
-    GNUNET_free ((void *) s_rd_1->data);
+    GNUNET_free_nz ((void *) s_rd_1->data);
     GNUNET_free (s_rd_1);
   }
   if (s_rd_2 != NULL)
   {
-    GNUNET_free ((void *) s_rd_2->data);
+    GNUNET_free_nz ((void *) s_rd_2->data);
     GNUNET_free (s_rd_2);
   }
   if (s_rd_3 != NULL)
   {
-    GNUNET_free ((void *) s_rd_3->data);
+    GNUNET_free_nz ((void *) s_rd_3->data);
     GNUNET_free (s_rd_3);
   }
 }
diff --git a/src/namestore/test_namestore_api_monitoring_existing.c b/src/namestore/test_namestore_api_monitoring_existing.c
index 040a63f91..728fcc25e 100644
--- a/src/namestore/test_namestore_api_monitoring_existing.c
+++ b/src/namestore/test_namestore_api_monitoring_existing.c
@@ -111,17 +111,17 @@ end (void *cls)
   }
   if (NULL != s_rd_1)
   {
-    GNUNET_free ((void *) s_rd_1->data);
+    GNUNET_free_nz ((void *) s_rd_1->data);
     GNUNET_free (s_rd_1);
   }
   if (NULL != s_rd_2)
   {
-    GNUNET_free ((void *) s_rd_2->data);
+    GNUNET_free_nz ((void *) s_rd_2->data);
     GNUNET_free (s_rd_2);
   }
   if (NULL != s_rd_3)
   {
-    GNUNET_free ((void *) s_rd_3->data);
+    GNUNET_free_nz ((void *) s_rd_3->data);
     GNUNET_free (s_rd_3);
   }
 }
diff --git a/src/namestore/test_namestore_api_remove.c b/src/namestore/test_namestore_api_remove.c
index 3f0c4c123..e575821e8 100644
--- a/src/namestore/test_namestore_api_remove.c
+++ b/src/namestore/test_namestore_api_remove.c
@@ -187,7 +187,7 @@ run (void *cls,
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 _ ("Namestore cannot store no block\n"));
   }
-  GNUNET_free ((void *) rd.data);
+  GNUNET_free_nz ((void *) rd.data);
 }
 
 
diff --git a/src/namestore/test_namestore_api_store.c b/src/namestore/test_namestore_api_store.c
index ab211aeae..9223b56a3 100644
--- a/src/namestore/test_namestore_api_store.c
+++ b/src/namestore/test_namestore_api_store.c
@@ -138,7 +138,7 @@ run (void *cls,
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 _ ("Namestore cannot store no block\n"));
   }
-  GNUNET_free ((void *) rd.data);
+  GNUNET_free_nz ((void *) rd.data);
 }
 
 
diff --git a/src/namestore/test_namestore_api_store_update.c b/src/namestore/test_namestore_api_store_update.c
index 65dbdbd8c..7a5a69a6c 100644
--- a/src/namestore/test_namestore_api_store_update.c
+++ b/src/namestore/test_namestore_api_store_update.c
@@ -274,7 +274,7 @@ run (void *cls,
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 _ ("Namestore cannot store no block\n"));
   }
-  GNUNET_free ((void *) rd.data);
+  GNUNET_free_nz ((void *) rd.data);
 }
 
 
diff --git a/src/namestore/test_namestore_api_zone_iteration.c b/src/namestore/test_namestore_api_zone_iteration.c
index d69b7cc62..a363ee28d 100644
--- a/src/namestore/test_namestore_api_zone_iteration.c
+++ b/src/namestore/test_namestore_api_zone_iteration.c
@@ -37,9 +37,9 @@ static struct GNUNET_NAMESTORE_Handle *nsh;
 
 static struct GNUNET_SCHEDULER_Task *endbadly_task;
 
-static struct GNUNET_CRYPTO_EcdsaPrivateKey *privkey;
+static struct GNUNET_CRYPTO_EcdsaPrivateKey privkey;
 
-static struct GNUNET_CRYPTO_EcdsaPrivateKey *privkey2;
+static struct GNUNET_CRYPTO_EcdsaPrivateKey privkey2;
 
 static struct GNUNET_NAMESTORE_ZoneIterator *zi;
 
@@ -88,32 +88,22 @@ end (void *cls)
     GNUNET_SCHEDULER_cancel (endbadly_task);
     endbadly_task = NULL;
   }
-  if (NULL != privkey)
-  {
-    GNUNET_free (privkey);
-    privkey = NULL;
-  }
-  if (NULL != privkey2)
-  {
-    GNUNET_free (privkey2);
-    privkey2 = NULL;
-  }
   GNUNET_free_non_null (s_name_1);
   GNUNET_free_non_null (s_name_2);
   GNUNET_free_non_null (s_name_3);
   if (NULL != s_rd_1)
   {
-    GNUNET_free ((void *) s_rd_1->data);
+    GNUNET_free_nz ((void *) s_rd_1->data);
     GNUNET_free (s_rd_1);
   }
   if (NULL != s_rd_2)
   {
-    GNUNET_free ((void *) s_rd_2->data);
+    GNUNET_free_nz ((void *) s_rd_2->data);
     GNUNET_free (s_rd_2);
   }
   if (NULL != s_rd_3)
   {
-    GNUNET_free ((void *) s_rd_3->data);
+    GNUNET_free_nz ((void *) s_rd_3->data);
     GNUNET_free (s_rd_3);
   }
   if (NULL != nsh)
@@ -161,7 +151,7 @@ zone_proc (void *cls,
 
   GNUNET_assert (NULL != zone);
   if (0 == GNUNET_memcmp (zone,
-                          privkey))
+                          &privkey))
   {
     if (0 == strcmp (label, s_name_1))
     {
@@ -207,7 +197,7 @@ zone_proc (void *cls,
     }
   }
   else if (0 == GNUNET_memcmp (zone,
-                               privkey2))
+                               &privkey2))
   {
     if (0 == strcmp (label, s_name_3))
     {
@@ -382,9 +372,11 @@ empty_zone_end (void *cls)
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Using zonekey file `%s' \n",
               hostkey_file);
-  privkey = GNUNET_CRYPTO_ecdsa_key_create_from_file (hostkey_file);
+  GNUNET_assert (GNUNET_SYSERR !=
+                 GNUNET_CRYPTO_ecdsa_key_from_file (hostkey_file,
+                                                    GNUNET_YES,
+                                                    &privkey));
   GNUNET_free (hostkey_file);
-  GNUNET_assert (privkey != NULL);
 
   GNUNET_asprintf (&hostkey_file,
                    "zonefiles%s%s",
@@ -393,16 +385,18 @@ empty_zone_end (void *cls)
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Using zonekey file `%s' \n",
               hostkey_file);
-  privkey2 = GNUNET_CRYPTO_ecdsa_key_create_from_file (hostkey_file);
+  GNUNET_assert (GNUNET_SYSERR !=
+                 GNUNET_CRYPTO_ecdsa_key_from_file (hostkey_file,
+                                                    GNUNET_YES,
+                                                    &privkey2));
   GNUNET_free (hostkey_file);
-  GNUNET_assert (privkey2 != NULL);
 
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Created record 1\n");
 
   GNUNET_asprintf (&s_name_1, "dummy1");
   s_rd_1 = create_record (1);
   GNUNET_NAMESTORE_records_store (nsh,
-                                  privkey,
+                                  &privkey,
                                   s_name_1,
                                   1, s_rd_1,
                                   &put_cont,
@@ -412,7 +406,7 @@ empty_zone_end (void *cls)
   GNUNET_asprintf (&s_name_2, "dummy2");
   s_rd_2 = create_record (1);
   GNUNET_NAMESTORE_records_store (nsh,
-                                  privkey,
+                                  &privkey,
                                   s_name_2,
                                   1, s_rd_2,
                                   &put_cont,
@@ -423,7 +417,7 @@ empty_zone_end (void *cls)
   GNUNET_asprintf (&s_name_3, "dummy3");
   s_rd_3 = create_record (1);
   GNUNET_NAMESTORE_records_store (nsh,
-                                  privkey2,
+                                  &privkey2,
                                   s_name_3,
                                   1,
                                   s_rd_3,
diff --git a/src/namestore/test_namestore_api_zone_iteration_nick.c b/src/namestore/test_namestore_api_zone_iteration_nick.c
index f5ffe3899..b0c4c8211 100644
--- a/src/namestore/test_namestore_api_zone_iteration_nick.c
+++ b/src/namestore/test_namestore_api_zone_iteration_nick.c
@@ -87,17 +87,17 @@ end (void *cls)
 
   if (s_rd_1 != NULL)
   {
-    GNUNET_free ((void *) s_rd_1->data);
+    GNUNET_free_nz ((void *) s_rd_1->data);
     GNUNET_free (s_rd_1);
   }
   if (s_rd_2 != NULL)
   {
-    GNUNET_free ((void *) s_rd_2->data);
+    GNUNET_free_nz ((void *) s_rd_2->data);
     GNUNET_free (s_rd_2);
   }
   if (s_rd_3 != NULL)
   {
-    GNUNET_free ((void *) s_rd_3->data);
+    GNUNET_free_nz ((void *) s_rd_3->data);
     GNUNET_free (s_rd_3);
   }
 }
diff --git a/src/namestore/test_namestore_api_zone_iteration_specific_zone.c b/src/namestore/test_namestore_api_zone_iteration_specific_zone.c
index 97093cb71..0534da001 100644
--- a/src/namestore/test_namestore_api_zone_iteration_specific_zone.c
+++ b/src/namestore/test_namestore_api_zone_iteration_specific_zone.c
@@ -93,17 +93,17 @@ end (void *cls)
   GNUNET_free_non_null (s_name_3);
   if (s_rd_1 != NULL)
   {
-    GNUNET_free ((void *) s_rd_1->data);
+    GNUNET_free_nz ((void *) s_rd_1->data);
     GNUNET_free (s_rd_1);
   }
   if (s_rd_2 != NULL)
   {
-    GNUNET_free ((void *) s_rd_2->data);
+    GNUNET_free_nz ((void *) s_rd_2->data);
     GNUNET_free (s_rd_2);
   }
   if (s_rd_3 != NULL)
   {
-    GNUNET_free ((void *) s_rd_3->data);
+    GNUNET_free_nz ((void *) s_rd_3->data);
     GNUNET_free (s_rd_3);
   }
   if (nsh != NULL)
diff --git a/src/namestore/test_namestore_api_zone_iteration_stop.c b/src/namestore/test_namestore_api_zone_iteration_stop.c
index 81fb4de7e..b71a8789c 100644
--- a/src/namestore/test_namestore_api_zone_iteration_stop.c
+++ b/src/namestore/test_namestore_api_zone_iteration_stop.c
@@ -34,9 +34,9 @@
 
 static struct GNUNET_NAMESTORE_Handle *nsh;
 
-static struct GNUNET_CRYPTO_EcdsaPrivateKey *privkey;
+static struct GNUNET_CRYPTO_EcdsaPrivateKey privkey;
 
-static struct GNUNET_CRYPTO_EcdsaPrivateKey *privkey2;
+static struct GNUNET_CRYPTO_EcdsaPrivateKey privkey2;
 
 static struct GNUNET_NAMESTORE_ZoneIterator *zi;
 
@@ -80,29 +80,19 @@ end (void *cls)
   GNUNET_free_non_null (s_name_3);
   if (s_rd_1 != NULL)
   {
-    GNUNET_free ((void *) s_rd_1->data);
+    GNUNET_free_nz ((void *) s_rd_1->data);
     GNUNET_free (s_rd_1);
   }
   if (s_rd_2 != NULL)
   {
-    GNUNET_free ((void *) s_rd_2->data);
+    GNUNET_free_nz ((void *) s_rd_2->data);
     GNUNET_free (s_rd_2);
   }
   if (s_rd_3 != NULL)
   {
-    GNUNET_free ((void *) s_rd_3->data);
+    GNUNET_free_nz ((void *) s_rd_3->data);
     GNUNET_free (s_rd_3);
   }
-  if (privkey != NULL)
-  {
-    GNUNET_free (privkey);
-    privkey = NULL;
-  }
-  if (privkey2 != NULL)
-  {
-    GNUNET_free (privkey2);
-    privkey2 = NULL;
-  }
 }
 
 
@@ -130,7 +120,7 @@ zone_proc (void *cls,
   int failed = GNUNET_NO;
 
   GNUNET_assert (NULL != zone);
-  if (0 == GNUNET_memcmp (zone, privkey))
+  if (0 == GNUNET_memcmp (zone, &privkey))
   {
     if (0 == strcmp (label, s_name_1))
     {
@@ -175,7 +165,7 @@ zone_proc (void *cls,
       GNUNET_break (0);
     }
   }
-  else if (0 == GNUNET_memcmp (zone, privkey2))
+  else if (0 == GNUNET_memcmp (zone, &privkey2))
   {
     if (0 == strcmp (label, s_name_3))
     {
@@ -368,10 +358,11 @@ empty_zone_proc_end (void *cls)
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Using zonekey file `%s' \n",
               hostkey_file);
-  privkey = GNUNET_CRYPTO_ecdsa_key_create_from_file (hostkey_file);
+  GNUNET_assert (GNUNET_SYSERR
+                 != GNUNET_CRYPTO_ecdsa_key_from_file (hostkey_file,
+                                                       GNUNET_YES,
+                                                       &privkey));
   GNUNET_free (hostkey_file);
-  GNUNET_assert (privkey != NULL);
-
   GNUNET_asprintf (&hostkey_file,
                    "zonefiles%s%s",
                    DIR_SEPARATOR_STR,
@@ -379,17 +370,19 @@ empty_zone_proc_end (void *cls)
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Using zonekey file `%s'\n",
               hostkey_file);
-  privkey2 = GNUNET_CRYPTO_ecdsa_key_create_from_file (hostkey_file);
+  GNUNET_assert (GNUNET_SYSERR !=
+                 GNUNET_CRYPTO_ecdsa_key_from_file (hostkey_file,
+                                                    GNUNET_YES,
+                                                    &privkey2));
   GNUNET_free (hostkey_file);
-  GNUNET_assert (privkey2 != NULL);
-
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Created record 1\n");
 
   GNUNET_asprintf (&s_name_1,
                    "dummy1");
   s_rd_1 = create_record (1);
-  GNUNET_NAMESTORE_records_store (nsh, privkey, s_name_1,
+  GNUNET_NAMESTORE_records_store (nsh,
+                                  &privkey, s_name_1,
                                   1, s_rd_1, &put_cont, NULL);
 
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
@@ -398,7 +391,7 @@ empty_zone_proc_end (void *cls)
                    "dummy2");
   s_rd_2 = create_record (1);
   GNUNET_NAMESTORE_records_store (nsh,
-                                  privkey,
+                                  &privkey,
                                   s_name_2,
                                   1,
                                   s_rd_2,
@@ -411,7 +404,7 @@ empty_zone_proc_end (void *cls)
   GNUNET_asprintf (&s_name_3, "dummy3");
   s_rd_3 = create_record (1);
   GNUNET_NAMESTORE_records_store (nsh,
-                                  privkey2,
+                                  &privkey2,
                                   s_name_3,
                                   1,
                                   s_rd_3,
diff --git a/src/nat-auto/gnunet-nat-auto.c b/src/nat-auto/gnunet-nat-auto.c
index d40f4ef32..95a7ced9e 100644
--- a/src/nat-auto/gnunet-nat-auto.c
+++ b/src/nat-auto/gnunet-nat-auto.c
@@ -359,7 +359,7 @@ main (int argc, char *const argv[])
   {
     global_ret = 1;
   }
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return global_ret;
 }
 
diff --git a/src/nat/gnunet-nat.c b/src/nat/gnunet-nat.c
index 857ce5093..5012d6455 100644
--- a/src/nat/gnunet-nat.c
+++ b/src/nat/gnunet-nat.c
@@ -468,7 +468,7 @@ main (int argc, char *const argv[])
   {
     global_ret = 1;
   }
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return global_ret;
 }
 
diff --git a/src/peerinfo-tool/gnunet-peerinfo.c b/src/peerinfo-tool/gnunet-peerinfo.c
index 4d4c4de33..df6c169b5 100644
--- a/src/peerinfo-tool/gnunet-peerinfo.c
+++ b/src/peerinfo-tool/gnunet-peerinfo.c
@@ -855,7 +855,7 @@ main (int argc, char *const *argv)
                              NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/peerinfo-tool/plugin_rest_peerinfo.c b/src/peerinfo-tool/plugin_rest_peerinfo.c
index 14559a8cf..6e156569a 100644
--- a/src/peerinfo-tool/plugin_rest_peerinfo.c
+++ b/src/peerinfo-tool/plugin_rest_peerinfo.c
@@ -272,7 +272,7 @@ cleanup_handle (void *cls)
   if (NULL != handle->emsg)
     GNUNET_free (handle->emsg);
   if (NULL != handle->address)
-    GNUNET_free ((char *) handle->address);
+    GNUNET_free_nz ((char *) handle->address);
   if (NULL != handle->expiration_str)
     GNUNET_free (handle->expiration_str);
   if (NULL != handle->pubkey)
diff --git a/src/pt/gnunet-daemon-pt.c b/src/pt/gnunet-daemon-pt.c
index f8765818b..bcc913bd2 100644
--- a/src/pt/gnunet-daemon-pt.c
+++ b/src/pt/gnunet-daemon-pt.c
@@ -1317,7 +1317,7 @@ main (int argc,
                              NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/pt/test_gns_vpn.c b/src/pt/test_gns_vpn.c
index 9bf497b16..69afca789 100644
--- a/src/pt/test_gns_vpn.c
+++ b/src/pt/test_gns_vpn.c
@@ -45,6 +45,7 @@
 #include "gnunet_gnsrecord_lib.h"
 #include "gnunet_gns_service.h"
 #include "gnunet_testing_lib.h"
+#include "gnunet_mhd_compat.h"
 
 #define PORT 8080
 #define TEST_DOMAIN "www.gnu"
@@ -121,7 +122,7 @@ copy_buffer (void *ptr,
 }
 
 
-static int
+static MHD_RESULT
 mhd_ahc (void *cls,
          struct MHD_Connection *connection,
          const char *url,
@@ -611,7 +612,7 @@ identity_cb (void *cls,
                                        1, &rd,
                                        &commence_testing,
                                        NULL);
-  GNUNET_free ((void **) rd.data);
+  GNUNET_free_nz ((void **) rd.data);
   GNUNET_free (rd_string);
 }
 
diff --git a/src/pt/test_gnunet_vpn.c b/src/pt/test_gnunet_vpn.c
index 42fd52c38..cb9bb61fe 100644
--- a/src/pt/test_gnunet_vpn.c
+++ b/src/pt/test_gnunet_vpn.c
@@ -29,6 +29,7 @@
 #include <microhttpd.h>
 #include "gnunet_vpn_service.h"
 #include "gnunet_testing_lib.h"
+#include "gnunet_mhd_compat.h"
 
 #define PORT 48080
 
@@ -96,7 +97,7 @@ copy_buffer (void *ptr, size_t size, size_t nmemb, void *ctx)
 }
 
 
-static int
+static MHD_RESULT
 mhd_ahc (void *cls,
          struct MHD_Connection *connection,
          const char *url,
diff --git a/src/regex/gnunet-daemon-regexprofiler.c b/src/regex/gnunet-daemon-regexprofiler.c
index eda58fdd2..d94b5ae46 100644
--- a/src/regex/gnunet-daemon-regexprofiler.c
+++ b/src/regex/gnunet-daemon-regexprofiler.c
@@ -118,7 +118,7 @@ shutdown_task (void *cls)
   }
   if (NULL != reannounce_task)
   {
-    GNUNET_free (GNUNET_SCHEDULER_cancel (reannounce_task));
+    GNUNET_free_nz (GNUNET_SCHEDULER_cancel (reannounce_task));
     reannounce_task = NULL;
   }
   if (NULL != dht_handle)
diff --git a/src/revocation/gnunet-revocation.c b/src/revocation/gnunet-revocation.c
index f5aa2d17e..8b7cf33c6 100644
--- a/src/revocation/gnunet-revocation.c
+++ b/src/revocation/gnunet-revocation.c
@@ -28,6 +28,10 @@
 #include "gnunet_revocation_service.h"
 #include "gnunet_identity_service.h"
 
+/**
+ * Pow passes
+ */
+static unsigned int pow_passes = 1;
 
 /**
  * Final status code.
@@ -55,6 +59,11 @@ static char *revoke_ego;
 static char *test_ego;
 
 /**
+ * -e option.
+ */
+static unsigned int epochs = 1;
+
+/**
  * Handle for revocation query.
  */
 static struct GNUNET_REVOCATION_Query *q;
@@ -80,10 +89,19 @@ static const struct GNUNET_CONFIGURATION_Handle *cfg;
 static unsigned long long matching_bits;
 
 /**
+ * Epoch length
+ */
+static struct GNUNET_TIME_Relative epoch_duration;
+
+/**
  * Task used for proof-of-work calculation.
  */
 static struct GNUNET_SCHEDULER_Task *pow_task;
 
+/**
+ * Proof-of-work object
+ */
+static struct GNUNET_REVOCATION_Pow proof_of_work;
 
 /**
  * Function run if the user aborts with CTRL-C.
@@ -93,6 +111,7 @@ static struct GNUNET_SCHEDULER_Task *pow_task;
 static void
 do_shutdown (void *cls)
 {
+  fprintf (stderr, "%s", _ ("Shutting down...\n"));
   if (NULL != el)
   {
     GNUNET_IDENTITY_ego_lookup_cancel (el);
@@ -188,37 +207,13 @@ print_revocation_result (void *cls, int is_valid)
 
 
 /**
- * Data needed to perform a revocation.
- */
-struct RevocationData
-{
-  /**
-   * Public key.
-   */
-  struct GNUNET_CRYPTO_EcdsaPublicKey key;
-
-  /**
-   * Revocation signature data.
-   */
-  struct GNUNET_CRYPTO_EcdsaSignature sig;
-
-  /**
-   * Proof of work (in NBO).
-   */
-  uint64_t pow GNUNET_PACKED;
-};
-
-
-/**
  * Perform the revocation.
  */
 static void
-perform_revocation (const struct RevocationData *rd)
+perform_revocation ()
 {
   h = GNUNET_REVOCATION_revoke (cfg,
-                                &rd->key,
-                                &rd->sig,
-                                rd->pow,
+                                &proof_of_work,
                                 &print_revocation_result,
                                 NULL);
 }
@@ -231,13 +226,13 @@ perform_revocation (const struct RevocationData *rd)
  * @param rd data to sync
  */
 static void
-sync_rd (const struct RevocationData *rd)
+sync_pow ()
 {
   if ((NULL != filename) &&
-      (sizeof(struct RevocationData) ==
+      (sizeof(struct GNUNET_REVOCATION_Pow) !=
        GNUNET_DISK_fn_write (filename,
-                             &rd,
-                             sizeof(rd),
+                             &proof_of_work,
+                             sizeof(struct GNUNET_REVOCATION_Pow),
                              GNUNET_DISK_PERM_USER_READ
                              | GNUNET_DISK_PERM_USER_WRITE)))
     GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "write", filename);
@@ -252,15 +247,16 @@ sync_rd (const struct RevocationData *rd)
 static void
 calculate_pow_shutdown (void *cls)
 {
-  struct RevocationData *rd = cls;
-
+  struct GNUNET_REVOCATION_PowCalculationHandle *ph = cls;
+  fprintf (stderr, "%s", _ ("Cancelling calculation.\n"));
+  sync_pow ();
   if (NULL != pow_task)
   {
     GNUNET_SCHEDULER_cancel (pow_task);
     pow_task = NULL;
   }
-  sync_rd (rd);
-  GNUNET_free (rd);
+  if (NULL != ph)
+    GNUNET_REVOCATION_pow_stop (ph);
 }
 
 
@@ -272,38 +268,26 @@ calculate_pow_shutdown (void *cls)
 static void
 calculate_pow (void *cls)
 {
-  struct RevocationData *rd = cls;
+  struct GNUNET_REVOCATION_PowCalculationHandle *ph = cls;
 
   /* store temporary results */
   pow_task = NULL;
-  if (0 == (rd->pow % 128))
-    sync_rd (rd);
-  /* display progress estimate */
-  if ((0 == ((1 << matching_bits) / 100 / 50)) ||
-      (0 == (rd->pow % ((1 << matching_bits) / 100 / 50))))
-    fprintf (stderr, "%s", ".");
-  if ((0 != rd->pow) && ((0 == ((1 << matching_bits) / 100)) ||
-                         (0 == (rd->pow % ((1 << matching_bits) / 100)))))
-    fprintf (stderr,
-             " - @ %3u%% (estimate)\n",
-             (unsigned int) (rd->pow * 100) / (1 << matching_bits));
+  if (0 == (pow_passes % 128))
+    sync_pow ();
   /* actually do POW calculation */
-  rd->pow++;
-  if (GNUNET_OK == GNUNET_REVOCATION_check_pow (&rd->key,
-                                                rd->pow,
-                                                (unsigned int) matching_bits))
+  if (GNUNET_OK == GNUNET_REVOCATION_pow_round (ph))
   {
     if ((NULL != filename) &&
-        (sizeof(struct RevocationData) !=
+        (sizeof(struct GNUNET_REVOCATION_Pow) !=
          GNUNET_DISK_fn_write (filename,
-                               rd,
-                               sizeof(struct RevocationData),
+                               &proof_of_work,
+                               sizeof(struct GNUNET_REVOCATION_Pow),
                                GNUNET_DISK_PERM_USER_READ
                                | GNUNET_DISK_PERM_USER_WRITE)))
       GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "write", filename);
     if (perform)
     {
-      perform_revocation (rd);
+      perform_revocation ();
     }
     else
     {
@@ -316,7 +300,19 @@ calculate_pow (void *cls)
     }
     return;
   }
-  pow_task = GNUNET_SCHEDULER_add_now (&calculate_pow, rd);
+  pow_passes++;
+  /**
+   * Otherwise CTRL-C does not work
+   */
+  if (0 == pow_passes % 128)
+    pow_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_MILLISECONDS,
+                                             &calculate_pow,
+                                             ph);
+  else
+    pow_task = GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_MILLISECONDS,
+                                             &calculate_pow,
+                                             ph);
+
 }
 
 
@@ -329,8 +325,9 @@ calculate_pow (void *cls)
 static void
 ego_callback (void *cls, const struct GNUNET_IDENTITY_Ego *ego)
 {
-  struct RevocationData *rd;
   struct GNUNET_CRYPTO_EcdsaPublicKey key;
+  const struct GNUNET_CRYPTO_EcdsaPrivateKey *privkey;
+  struct GNUNET_REVOCATION_PowCalculationHandle *ph = NULL;
 
   el = NULL;
   if (NULL == ego)
@@ -340,44 +337,55 @@ ego_callback (void *cls, const struct GNUNET_IDENTITY_Ego *ego)
     return;
   }
   GNUNET_IDENTITY_ego_get_public_key (ego, &key);
-  rd = GNUNET_new (struct RevocationData);
+  privkey = GNUNET_IDENTITY_ego_get_private_key (ego);
+  memset (&proof_of_work, 0, sizeof (proof_of_work));
   if ((NULL != filename) && (GNUNET_YES == GNUNET_DISK_file_test (filename)) &&
-      (sizeof(struct RevocationData) ==
-       GNUNET_DISK_fn_read (filename, rd, sizeof(struct RevocationData))))
+      (sizeof(proof_of_work) ==
+       GNUNET_DISK_fn_read (filename, &proof_of_work, sizeof(proof_of_work))))
   {
-    if (0 != GNUNET_memcmp (&rd->key, &key))
+    if (0 != GNUNET_memcmp (&proof_of_work.key, &key))
     {
       fprintf (stderr,
                _ ("Error: revocation certificate in `%s' is not for `%s'\n"),
                filename,
                revoke_ego);
-      GNUNET_free (rd);
       return;
     }
-  }
-  else
-  {
-    GNUNET_REVOCATION_sign_revocation (GNUNET_IDENTITY_ego_get_private_key (
-                                         ego),
-                                       &rd->sig);
-    rd->key = key;
-  }
-  if (GNUNET_YES ==
-      GNUNET_REVOCATION_check_pow (&key, rd->pow, (unsigned int) matching_bits))
-  {
-    fprintf (stderr, "%s", _ ("Revocation certificate ready\n"));
-    if (perform)
-      perform_revocation (rd);
-    else
-      GNUNET_SCHEDULER_shutdown ();
-    GNUNET_free (rd);
-    return;
+    if (GNUNET_YES ==
+        GNUNET_REVOCATION_check_pow (&proof_of_work,
+                                     (unsigned int) matching_bits,
+                                     epoch_duration))
+    {
+      fprintf (stderr, "%s", _ ("Revocation certificate ready\n"));
+      if (perform)
+        perform_revocation ();
+      else
+        GNUNET_SCHEDULER_shutdown ();
+      return;
+    }
+    /**
+     * Certificate not yet ready
+     */
+    fprintf (stderr,
+             "%s",
+             _ ("Continuing calculation where left off...\n"));
+    ph = GNUNET_REVOCATION_pow_start (&proof_of_work,
+                                      epochs,
+                                      matching_bits);
   }
   fprintf (stderr,
            "%s",
            _ ("Revocation certificate not ready, calculating proof of work\n"));
-  pow_task = GNUNET_SCHEDULER_add_now (&calculate_pow, rd);
-  GNUNET_SCHEDULER_add_shutdown (&calculate_pow_shutdown, rd);
+  if (NULL == ph)
+  {
+    GNUNET_REVOCATION_pow_init (privkey,
+                                &proof_of_work);
+    ph = GNUNET_REVOCATION_pow_start (&proof_of_work,
+                                      epochs, /* Epochs */
+                                      matching_bits);
+  }
+  pow_task = GNUNET_SCHEDULER_add_now (&calculate_pow, ph);
+  GNUNET_SCHEDULER_add_shutdown (&calculate_pow_shutdown, ph);
 }
 
 
@@ -396,7 +404,6 @@ run (void *cls,
      const struct GNUNET_CONFIGURATION_Handle *c)
 {
   struct GNUNET_CRYPTO_EcdsaPublicKey pk;
-  struct RevocationData rd;
 
   cfg = c;
   if (NULL != test_ego)
@@ -429,6 +436,17 @@ run (void *cls,
                                "WORKBITS");
     return;
   }
+  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_time (cfg,
+                                                        "REVOCATION",
+                                                        "EPOCH_DURATION",
+                                                        &epoch_duration))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "REVOCATION",
+                               "EPOCH_DURATION");
+    return;
+  }
+
   if (NULL != revoke_ego)
   {
     if (! perform && (NULL == filename))
@@ -445,7 +463,9 @@ run (void *cls,
   }
   if ((NULL != filename) && (perform))
   {
-    if (sizeof(rd) != GNUNET_DISK_fn_read (filename, &rd, sizeof(rd)))
+    if (sizeof(proof_of_work) != GNUNET_DISK_fn_read (filename,
+                                                      &proof_of_work,
+                                                      sizeof(proof_of_work)))
     {
       fprintf (stderr,
                _ ("Failed to read revocation certificate from `%s'\n"),
@@ -454,18 +474,20 @@ run (void *cls,
     }
     GNUNET_SCHEDULER_add_shutdown (&do_shutdown, NULL);
     if (GNUNET_YES !=
-        GNUNET_REVOCATION_check_pow (&rd.key,
-                                     rd.pow,
-                                     (unsigned int) matching_bits))
+        GNUNET_REVOCATION_check_pow (&proof_of_work,
+                                     (unsigned int) matching_bits,
+                                     epoch_duration))
     {
-      struct RevocationData *cp = GNUNET_new (struct RevocationData);
+      struct GNUNET_REVOCATION_PowCalculationHandle *ph;
+      ph = GNUNET_REVOCATION_pow_start (&proof_of_work,
+                                        epochs, /* Epochs */
+                                        matching_bits);
 
-      *cp = rd;
-      pow_task = GNUNET_SCHEDULER_add_now (&calculate_pow, cp);
-      GNUNET_SCHEDULER_add_shutdown (&calculate_pow_shutdown, cp);
+      pow_task = GNUNET_SCHEDULER_add_now (&calculate_pow, ph);
+      GNUNET_SCHEDULER_add_shutdown (&calculate_pow_shutdown, ph);
       return;
     }
-    perform_revocation (&rd);
+    perform_revocation ();
     return;
   }
   fprintf (stderr, "%s", _ ("No action specified. Nothing to do.\n"));
@@ -511,6 +533,12 @@ main (int argc, char *const *argv)
                                  gettext_noop (
                                    "test if the public key KEY has been revoked"),
                                  &test_ego),
+    GNUNET_GETOPT_option_uint ('e',
+                               "epochs",
+                               "EPOCHS",
+                               gettext_noop (
+                                 "number of epochs to calculate for"),
+                               &epochs),
 
     GNUNET_GETOPT_OPTION_END
   };
@@ -527,7 +555,7 @@ main (int argc, char *const *argv)
                                           NULL))
         ? ret
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/revocation/gnunet-service-revocation.c b/src/revocation/gnunet-service-revocation.c
index 3e811cd9a..3c08e8452 100644
--- a/src/revocation/gnunet-service-revocation.c
+++ b/src/revocation/gnunet-service-revocation.c
@@ -129,6 +129,11 @@ static struct GNUNET_SET_ListenHandle *revocation_union_listen_handle;
 static unsigned long long revocation_work_required;
 
 /**
+ * Length of an expiration expoch
+ */
+static struct GNUNET_TIME_Relative epoch_duration;
+
+/**
  * Our application ID for set union operations.  Must be the
  * same for all (compatible) peers.
  */
@@ -167,25 +172,15 @@ new_peer_entry (const struct GNUNET_PeerIdentity *peer)
 static int
 verify_revoke_message (const struct RevokeMessage *rm)
 {
-  if (GNUNET_YES !=
-      GNUNET_REVOCATION_check_pow (&rm->public_key,
-                                   rm->proof_of_work,
-                                   (unsigned int) revocation_work_required))
+  if (GNUNET_YES != GNUNET_REVOCATION_check_pow (&rm->proof_of_work,
+                                   (unsigned int) revocation_work_required,
+                                   epoch_duration))
   {
     GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                 "Proof of work invalid!\n");
     GNUNET_break_op (0);
     return GNUNET_NO;
   }
-  if (GNUNET_OK !=
-      GNUNET_CRYPTO_ecdsa_verify_ (GNUNET_SIGNATURE_PURPOSE_REVOCATION,
-                                   &rm->purpose,
-                                   &rm->signature,
-                                   &rm->public_key))
-  {
-    GNUNET_break_op (0);
-    return GNUNET_NO;
-  }
   return GNUNET_YES;
 }
 
@@ -308,7 +303,7 @@ publicize_rm (const struct RevokeMessage *rm)
   struct GNUNET_HashCode hc;
   struct GNUNET_SET_Element e;
 
-  GNUNET_CRYPTO_hash (&rm->public_key,
+  GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
                       sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                       &hc);
   if (GNUNET_YES ==
@@ -848,6 +843,20 @@ run (void *cls,
     GNUNET_free (fn);
     return;
   }
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (cfg,
+                                             "REVOCATION",
+                                             "EPOCH_DURATION",
+                                             &epoch_duration))
+  {
+    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                               "REVOCATION",
+                               "EPOCH_DURATION");
+    GNUNET_SCHEDULER_shutdown ();
+    GNUNET_free (fn);
+    return;
+  }
+
   revocation_set = GNUNET_SET_create (cfg,
                                       GNUNET_SET_OPERATION_UNION);
   revocation_union_listen_handle
@@ -893,7 +902,7 @@ run (void *cls,
       return;
     }
     GNUNET_break (0 == ntohl (rm->reserved));
-    GNUNET_CRYPTO_hash (&rm->public_key,
+    GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
                         sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                         &hc);
     GNUNET_break (GNUNET_OK ==
diff --git a/src/revocation/plugin_block_revocation.c b/src/revocation/plugin_block_revocation.c
index 8d16b8781..291c56f70 100644
--- a/src/revocation/plugin_block_revocation.c
+++ b/src/revocation/plugin_block_revocation.c
@@ -52,6 +52,7 @@
 struct InternalContext
 {
   unsigned int matching_bits;
+  struct GNUNET_TIME_Relative epoch_duration;
 };
 
 
@@ -142,24 +143,15 @@ block_plugin_revocation_evaluate (void *cls,
     GNUNET_break_op (0);
     return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
   }
-  if (GNUNET_YES !=
-      GNUNET_REVOCATION_check_pow (&rm->public_key,
-                                   rm->proof_of_work,
-                                   ic->matching_bits))
+  if (0 >=
+      GNUNET_REVOCATION_check_pow (&rm->proof_of_work,
+                                   ic->matching_bits,
+                                   ic->epoch_duration))
   {
     GNUNET_break_op (0);
     return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
   }
-  if (GNUNET_OK !=
-      GNUNET_CRYPTO_ecdsa_verify_ (GNUNET_SIGNATURE_PURPOSE_REVOCATION,
-                                   &rm->purpose,
-                                   &rm->signature,
-                                   &rm->public_key))
-  {
-    GNUNET_break_op (0);
-    return GNUNET_BLOCK_EVALUATION_RESULT_INVALID;
-  }
-  GNUNET_CRYPTO_hash (&rm->public_key,
+  GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
                       sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                       &chash);
   if (GNUNET_YES ==
@@ -195,7 +187,7 @@ block_plugin_revocation_get_key (void *cls,
     GNUNET_break_op (0);
     return GNUNET_SYSERR;
   }
-  GNUNET_CRYPTO_hash (&rm->public_key,
+  GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
                       sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                       key);
   return GNUNET_OK;
@@ -218,6 +210,7 @@ libgnunet_plugin_block_revocation_init (void *cls)
   struct GNUNET_BLOCK_PluginFunctions *api;
   struct InternalContext *ic;
   unsigned long long matching_bits;
+  struct GNUNET_TIME_Relative epoch_duration;
 
   if (GNUNET_OK !=
       GNUNET_CONFIGURATION_get_value_number (cfg,
@@ -225,6 +218,12 @@ libgnunet_plugin_block_revocation_init (void *cls)
                                              "WORKBITS",
                                              &matching_bits))
     return NULL;
+  if (GNUNET_OK !=
+      GNUNET_CONFIGURATION_get_value_time (cfg,
+                                           "REVOCATION",
+                                           "EPOCH_DURATION",
+                                           &epoch_duration))
+    return NULL;
 
   api = GNUNET_new (struct GNUNET_BLOCK_PluginFunctions);
   api->evaluate = &block_plugin_revocation_evaluate;
@@ -233,6 +232,7 @@ libgnunet_plugin_block_revocation_init (void *cls)
   api->types = types;
   ic = GNUNET_new (struct InternalContext);
   ic->matching_bits = (unsigned int) matching_bits;
+  ic->epoch_duration = epoch_duration;
   api->cls = ic;
   return api;
 }
diff --git a/src/revocation/revocation.conf.in b/src/revocation/revocation.conf.in
index 5ad41cd49..346168785 100644
--- a/src/revocation/revocation.conf.in
+++ b/src/revocation/revocation.conf.in
@@ -14,5 +14,6 @@ UNIX_MATCH_GID = YES
 # (using only a single-core) with SCRYPT.
 # DO NOT CHANGE THIS VALUE, doing so will break the protocol!
 WORKBITS = 25
+EPOCH_DURATION = 356 d
 
 DATABASE = $GNUNET_DATA_HOME/revocation.dat
diff --git a/src/revocation/revocation.h b/src/revocation/revocation.h
index b6e7a07ec..868c2b853 100644
--- a/src/revocation/revocation.h
+++ b/src/revocation/revocation.h
@@ -27,6 +27,7 @@
 #define REVOCATION_H
 
 #include "gnunet_util_lib.h"
+#include "gnunet_revocation_service.h"
 
 GNUNET_NETWORK_STRUCT_BEGIN
 
@@ -91,23 +92,7 @@ struct RevokeMessage
   /**
    * Number that causes a hash collision with the @e public_key.
    */
-  uint64_t proof_of_work GNUNET_PACKED;
-
-  /**
-   * Signature confirming revocation.
-   */
-  struct GNUNET_CRYPTO_EcdsaSignature signature;
-
-  /**
-   * Must have purpose #GNUNET_SIGNATURE_PURPOSE_REVOCATION,
-   * size expands over the public key. (@deprecated)
-   */
-  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
-
-  /**
-   * Key to revoke.
-   */
-  struct GNUNET_CRYPTO_EcdsaPublicKey public_key;
+  struct GNUNET_REVOCATION_Pow proof_of_work;
 };
 
 
diff --git a/src/revocation/revocation_api.c b/src/revocation/revocation_api.c
index 4755d4816..18a312ab8 100644
--- a/src/revocation/revocation_api.c
+++ b/src/revocation/revocation_api.c
@@ -27,8 +27,7 @@
 #include "gnunet_signatures.h"
 #include "gnunet_protocols.h"
 #include "revocation.h"
-#include <gcrypt.h>
-
+#include <inttypes.h>
 
 /**
  * Handle for the key revocation query.
@@ -53,6 +52,58 @@ struct GNUNET_REVOCATION_Query
 
 
 /**
+ * Helper struct that holds a found pow nonce
+ * and the corresponding number of leading zeroes.
+ */
+struct BestPow
+{
+  /**
+   * PoW nonce
+   */
+  uint64_t pow;
+
+  /**
+   * Corresponding zero bits in hash
+   */
+  unsigned int bits;
+};
+
+
+/**
+ * The handle to a PoW calculation.
+ * Used in iterative PoW rounds.
+ */
+struct GNUNET_REVOCATION_PowCalculationHandle
+{
+  /**
+   * Current set of found PoWs
+   */
+  struct BestPow best[POW_COUNT];
+
+  /**
+   * The final PoW result data structure.
+   */
+  struct GNUNET_REVOCATION_Pow *pow;
+
+  /**
+   * The current nonce to try
+   */
+  uint64_t current_pow;
+
+  /**
+   * Epochs how long the PoW should be valid.
+   * This is added on top of the difficulty in the PoW.
+   */
+  unsigned int epochs;
+
+  /**
+   * The difficulty (leading zeros) to achieve.
+   */
+  unsigned int difficulty;
+
+};
+
+/**
  * Generic error handler, called with the appropriate
  * error code and the same closure specified at the creation of
  * the message queue.
@@ -235,6 +286,7 @@ handle_revocation_response (void *cls,
  * @param key public key of the key to revoke
  * @param sig signature to use on the revocation (should have been
  *            created using #GNUNET_REVOCATION_sign_revocation).
+ * @param ts  revocation timestamp
  * @param pow proof of work to use (should have been created by
  *            iteratively calling #GNUNET_REVOCATION_check_pow)
  * @param func funtion to call with the result of the check
@@ -245,9 +297,7 @@ handle_revocation_response (void *cls,
  */
 struct GNUNET_REVOCATION_Handle *
 GNUNET_REVOCATION_revoke (const struct GNUNET_CONFIGURATION_Handle *cfg,
-                          const struct GNUNET_CRYPTO_EcdsaPublicKey *key,
-                          const struct GNUNET_CRYPTO_EcdsaSignature *sig,
-                          uint64_t pow,
+                          const struct GNUNET_REVOCATION_Pow *pow,
                           GNUNET_REVOCATION_Callback func,
                           void *func_cls)
 {
@@ -261,23 +311,39 @@ GNUNET_REVOCATION_revoke (const struct GNUNET_CONFIGURATION_Handle *cfg,
     GNUNET_MQ_handler_end ()
   };
   unsigned long long matching_bits;
+  struct GNUNET_TIME_Relative epoch_duration;
   struct RevokeMessage *rm;
   struct GNUNET_MQ_Envelope *env;
 
-  if ((GNUNET_OK ==
+  if ((GNUNET_OK !=
        GNUNET_CONFIGURATION_get_value_number (cfg,
                                               "REVOCATION",
                                               "WORKBITS",
-                                              &matching_bits)) &&
-      (GNUNET_YES !=
-       GNUNET_REVOCATION_check_pow (key,
-                                    pow,
-                                    (unsigned int) matching_bits)))
+                                              &matching_bits)))
+  {
+    GNUNET_break (0);
+    GNUNET_free (h);
+    return NULL;
+  }
+  if ((GNUNET_OK !=
+       GNUNET_CONFIGURATION_get_value_time (cfg,
+                                            "REVOCATION",
+                                            "EPOCH_DURATION",
+                                            &epoch_duration)))
   {
     GNUNET_break (0);
     GNUNET_free (h);
     return NULL;
   }
+  if (GNUNET_YES != GNUNET_REVOCATION_check_pow (pow,
+                                                 (unsigned int) matching_bits,
+                                                 epoch_duration))
+  {
+    GNUNET_break (0);
+    GNUNET_free (h);
+    return NULL;
+  }
+
 
   h->mq = GNUNET_CLIENT_connect (cfg,
                                  "revocation",
@@ -294,12 +360,7 @@ GNUNET_REVOCATION_revoke (const struct GNUNET_CONFIGURATION_Handle *cfg,
   env = GNUNET_MQ_msg (rm,
                        GNUNET_MESSAGE_TYPE_REVOCATION_REVOKE);
   rm->reserved = htonl (0);
-  rm->proof_of_work = pow;
-  rm->purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_REVOCATION);
-  rm->purpose.size = htonl (sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose)
-                            + sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey));
-  rm->public_key = *key;
-  rm->signature = *sig;
+  rm->proof_of_work = *pow;
   GNUNET_MQ_send (h->mq,
                   env);
   return h;
@@ -342,56 +403,263 @@ count_leading_zeroes (const struct GNUNET_HashCode *hash)
 
 
 /**
- * Check if the given proof-of-work value
- * would be acceptable for revoking the given key.
+ * Calculate the average zeros in the pows.
  *
- * @param key key to check for
- * @param pow proof of work value
+ * @param ph the PowHandle
+ * @return the average number of zeroes.
+ */
+static unsigned int
+calculate_score (const struct GNUNET_REVOCATION_PowCalculationHandle *ph)
+{
+  double sum = 0.0;
+  for (unsigned int j = 0; j<POW_COUNT; j++)
+    sum += ph->best[j].bits;
+  double avg = sum / POW_COUNT;
+  return avg;
+}
+
+
+/**
+ * Check if the given proof-of-work is valid.
+ *
+ * @param pow proof of work
  * @param matching_bits how many bits must match (configuration)
+ * @param epoch_duration length of single epoch in configuration
+ * @return #GNUNET_YES if the @a pow is acceptable, #GNUNET_NO if not
+ */
+enum GNUNET_GenericReturnValue
+GNUNET_REVOCATION_check_pow (const struct GNUNET_REVOCATION_Pow *pow,
+                             unsigned int difficulty,
+                             struct GNUNET_TIME_Relative epoch_duration)
+{
+  char buf[sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey)
+           + sizeof (struct GNUNET_TIME_AbsoluteNBO)
+           + sizeof (uint64_t)] GNUNET_ALIGN;
+  struct GNUNET_REVOCATION_SignaturePurpose spurp;
+  struct GNUNET_HashCode result;
+  struct GNUNET_TIME_Absolute ts;
+  struct GNUNET_TIME_Absolute exp;
+  struct GNUNET_TIME_Relative ttl;
+  struct GNUNET_TIME_Relative buffer;
+  unsigned int score = 0;
+  unsigned int tmp_score = 0;
+  unsigned int epochs;
+  uint64_t pow_val;
+
+  /**
+   * Check if signature valid
+   */
+  spurp.key = pow->key;
+  spurp.timestamp = pow->timestamp;
+  spurp.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_REVOCATION);
+  spurp.purpose.size = htonl (sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose)
+                              + sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey)
+                              + sizeof (struct GNUNET_TIME_AbsoluteNBO));
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_ecdsa_verify_ (GNUNET_SIGNATURE_PURPOSE_REVOCATION,
+                                   &spurp.purpose,
+                                   &pow->signature,
+                                   &pow->key))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Proof of work signature invalid!\n");
+    return GNUNET_NO;
+  }
+
+  /**
+   * First, check if any duplicates are in the PoW set
+   */
+  for (unsigned int i = 0; i < POW_COUNT; i++)
+  {
+    for (unsigned int j = i + 1; j < POW_COUNT; j++)
+    {
+      if (pow->pow[i] == pow->pow[j])
+        return GNUNET_NO;
+    }
+  }
+  GNUNET_memcpy (&buf[sizeof(uint64_t)],
+                 &pow->timestamp,
+                 sizeof (uint64_t));
+  GNUNET_memcpy (&buf[sizeof(uint64_t) * 2],
+                 &pow->key,
+                 sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey));
+  for (unsigned int i = 0; i < POW_COUNT; i++)
+  {
+    pow_val = GNUNET_ntohll (pow->pow[i]);
+    GNUNET_memcpy (buf, &pow_val, sizeof(uint64_t));
+    GNUNET_CRYPTO_pow_hash ("gnunet-revocation-proof-of-work",
+                            buf,
+                            sizeof(buf),
+                            &result);
+    tmp_score = count_leading_zeroes (&result);
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "Score %u with %" PRIu64 " (#%u)\n",
+                tmp_score, pow_val, i);
+    score += tmp_score;
+
+  }
+  score = score / POW_COUNT;
+  if (score < difficulty)
+    return GNUNET_NO;
+  epochs = score - difficulty;
+
+  /**
+   * Check expiration
+   */
+  ts = GNUNET_TIME_absolute_ntoh (pow->timestamp);
+  ttl = GNUNET_TIME_relative_multiply (epoch_duration,
+                                       epochs);
+  /**
+   * Extend by 10% for unsynchronized clocks
+   */
+  buffer = GNUNET_TIME_relative_divide (epoch_duration,
+                                        10);
+  exp = GNUNET_TIME_absolute_add (ts, ttl);
+  exp = GNUNET_TIME_absolute_add (exp,
+                                  buffer);
+
+  if (0 != GNUNET_TIME_absolute_get_remaining (ts).rel_value_us)
+    return GNUNET_NO; /* Not yet valid. */
+  /* Revert to actual start time */
+  ts = GNUNET_TIME_absolute_add (ts,
+                                 buffer);
+
+  if (0 == GNUNET_TIME_absolute_get_remaining (exp).rel_value_us)
+    return GNUNET_NO; /* expired */
+  return GNUNET_YES;
+}
+
+
+/**
+ * Initializes a fresh PoW computation.
+ *
+ * @param key the key to calculate the PoW for.
+ * @param[out] pow starting point for PoW calculation (not yet valid)
+ */
+void
+GNUNET_REVOCATION_pow_init (const struct GNUNET_CRYPTO_EcdsaPrivateKey *key,
+                            struct GNUNET_REVOCATION_Pow *pow)
+{
+  struct GNUNET_TIME_Absolute ts = GNUNET_TIME_absolute_get ();
+  struct GNUNET_REVOCATION_SignaturePurpose rp;
+
+  /**
+   * Predate the validity period to prevent rejections due to
+   * unsynchronized clocks
+   */
+  ts = GNUNET_TIME_absolute_subtract (ts,
+                                      GNUNET_TIME_UNIT_WEEKS);
+
+  pow->timestamp = GNUNET_TIME_absolute_hton (ts);
+  rp.timestamp = pow->timestamp;
+  rp.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_REVOCATION);
+  rp.purpose.size = htonl (sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose)
+                           + sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey)
+                           + sizeof (struct GNUNET_TIME_AbsoluteNBO));
+  GNUNET_CRYPTO_ecdsa_key_get_public (key, &pow->key);
+  rp.key = pow->key;
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CRYPTO_ecdsa_sign_ (key,
+                                            &rp.purpose,
+                                            &pow->signature));
+}
+
+
+/**
+ * Starts a proof-of-work calculation given the pow object as well as
+ * target epochs and difficulty.
+ *
+ * @param pow the PoW to based calculations on.
+ * @param epochs the number of epochs for which the PoW must be valid.
+ * @param difficulty the base difficulty of the PoW.
+ * @return a handle for use in PoW rounds
+ */
+struct GNUNET_REVOCATION_PowCalculationHandle*
+GNUNET_REVOCATION_pow_start (struct GNUNET_REVOCATION_Pow *pow,
+                             int epochs,
+                             unsigned int difficulty)
+{
+  struct GNUNET_REVOCATION_PowCalculationHandle *pc;
+
+  pc = GNUNET_new (struct GNUNET_REVOCATION_PowCalculationHandle);
+  pc->pow = pow;
+  pc->current_pow = GNUNET_CRYPTO_random_u64 (GNUNET_CRYPTO_QUALITY_WEAK,
+                                              UINT64_MAX);
+  pc->difficulty = difficulty;
+  pc->epochs = epochs;
+  return pc;
+}
+
+
+/**
+ * Calculate a key revocation valid for broadcasting for a number
+ * of epochs.
+ *
+ * @param pc handle to the PoW, initially called with NULL.
+ * @param epochs number of epochs for which the revocation must be valid.
+ * @param pow current pow value to try
+ * @param difficulty current base difficulty to achieve
  * @return #GNUNET_YES if the @a pow is acceptable, #GNUNET_NO if not
  */
-int
-GNUNET_REVOCATION_check_pow (const struct GNUNET_CRYPTO_EcdsaPublicKey *key,
-                             uint64_t pow,
-                             unsigned int matching_bits)
+enum GNUNET_GenericReturnValue
+GNUNET_REVOCATION_pow_round (struct GNUNET_REVOCATION_PowCalculationHandle *pc)
 {
   char buf[sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey)
-           + sizeof(pow)] GNUNET_ALIGN;
+           + sizeof (uint64_t)
+           + sizeof (uint64_t)] GNUNET_ALIGN;
   struct GNUNET_HashCode result;
+  unsigned int zeros;
+
+  pc->current_pow++;
 
-  GNUNET_memcpy (buf, &pow, sizeof(pow));
-  GNUNET_memcpy (&buf[sizeof(pow)], key,
+  /**
+   * Do not try duplicates
+   */
+  for (unsigned int i = 0; i < POW_COUNT; i++)
+    if (pc->current_pow == pc->best[i].pow)
+      return GNUNET_NO;
+
+  GNUNET_memcpy (buf, &pc->current_pow, sizeof(uint64_t));
+  GNUNET_memcpy (&buf[sizeof(uint64_t)],
+                 &pc->pow->timestamp,
+                 sizeof (uint64_t));
+  GNUNET_memcpy (&buf[sizeof(uint64_t) * 2],
+                 &pc->pow->key,
                  sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey));
   GNUNET_CRYPTO_pow_hash ("gnunet-revocation-proof-of-work",
                           buf,
                           sizeof(buf),
                           &result);
-  return (count_leading_zeroes (&result) >=
-          matching_bits) ? GNUNET_YES : GNUNET_NO;
+  zeros = count_leading_zeroes (&result);
+  for (unsigned int i = 0; i < POW_COUNT; i++)
+  {
+    if (pc->best[i].bits < zeros)
+    {
+      pc->best[i].bits = zeros;
+      pc->best[i].pow = pc->current_pow;
+      pc->pow->pow[i] = GNUNET_htonll (pc->current_pow);
+      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                  "New best score %u with %" PRIu64 " (#%u)\n",
+                  zeros, pc->current_pow, i);
+      break;
+    }
+  }
+  return calculate_score (pc) >= pc->difficulty + pc->epochs ? GNUNET_YES :
+         GNUNET_NO;
 }
 
 
 /**
- * Create a revocation signature.
+ * Stop a PoW calculation
  *
- * @param key private key of the key to revoke
- * @param sig where to write the revocation signature
+ * @param pc the calculation to clean up
+ * @return #GNUNET_YES if pow valid, #GNUNET_NO if pow was set but is not
+ * valid
  */
 void
-GNUNET_REVOCATION_sign_revocation (const struct
-                                   GNUNET_CRYPTO_EcdsaPrivateKey *key,
-                                   struct GNUNET_CRYPTO_EcdsaSignature *sig)
+GNUNET_REVOCATION_pow_stop (struct GNUNET_REVOCATION_PowCalculationHandle *pc)
 {
-  struct RevokeMessage rm;
-
-  rm.purpose.purpose = htonl (GNUNET_SIGNATURE_PURPOSE_REVOCATION);
-  rm.purpose.size = htonl (sizeof(struct GNUNET_CRYPTO_EccSignaturePurpose)
-                           + sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey));
-  GNUNET_CRYPTO_ecdsa_key_get_public (key, &rm.public_key);
-  GNUNET_assert (GNUNET_OK ==
-                 GNUNET_CRYPTO_ecdsa_sign_ (key,
-                                            &rm.purpose,
-                                            sig));
+  GNUNET_free (pc);
 }
 
 
diff --git a/src/revocation/test_revocation.c b/src/revocation/test_revocation.c
index 012bac09e..f193d5f6c 100644
--- a/src/revocation/test_revocation.c
+++ b/src/revocation/test_revocation.c
@@ -45,7 +45,7 @@ struct TestPeer
   struct GNUNET_IDENTITY_EgoLookup *ego_lookup;
   struct GNUNET_REVOCATION_Handle *revok_handle;
   struct GNUNET_CORE_Handle *ch;
-  uint64_t pow;
+  struct GNUNET_REVOCATION_PowCalculationHandle *pow;
 };
 
 static struct TestPeer testpeers[2];
@@ -131,7 +131,7 @@ check_revocation (void *cls)
 
 
 static void
-revocation_cb (void *cls, int is_valid)
+revocation_cb (void *cls, enum GNUNET_GenericReturnValue is_valid)
 {
   testpeers[1].revok_handle = NULL;
   if (GNUNET_NO == is_valid)
@@ -141,11 +141,14 @@ revocation_cb (void *cls, int is_valid)
   }
 }
 
+struct GNUNET_REVOCATION_Pow proof_of_work;
+
 
 static void
 ego_cb (void *cls, const struct GNUNET_IDENTITY_Ego *ego)
 {
   static int completed = 0;
+  const struct GNUNET_CRYPTO_EcdsaPrivateKey *privkey;
 
   if ((NULL != ego) && (cls == &testpeers[0]))
   {
@@ -159,17 +162,20 @@ ego_cb (void *cls, const struct GNUNET_IDENTITY_Ego *ego)
     testpeers[1].ego_lookup = NULL;
     testpeers[1].privkey = GNUNET_IDENTITY_ego_get_private_key (ego);
     GNUNET_IDENTITY_ego_get_public_key (ego, &testpeers[1].pubkey);
-    GNUNET_REVOCATION_sign_revocation (testpeers[1].privkey, &testpeers[1].sig);
-
     GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Calculating proof of work...\n");
-    testpeers[1].pow = 0;
+    privkey = GNUNET_IDENTITY_ego_get_private_key (ego);
+    memset (&proof_of_work, 0, sizeof (proof_of_work));
+    GNUNET_REVOCATION_pow_init (privkey,
+                                &proof_of_work);
+    testpeers[1].pow = GNUNET_REVOCATION_pow_start (&proof_of_work,
+                                                    1,
+                                                    5);
     int res =
-      GNUNET_REVOCATION_check_pow (&testpeers[1].pubkey, testpeers[1].pow, 5);
+      GNUNET_REVOCATION_pow_round (testpeers[1].pow);
     while (GNUNET_OK != res)
     {
-      testpeers[1].pow++;
       res =
-        GNUNET_REVOCATION_check_pow (&testpeers[1].pubkey, testpeers[1].pow, 5);
+        GNUNET_REVOCATION_pow_round (testpeers[1].pow);
     }
     fprintf (stderr, "Done calculating proof of work\n");
     completed++;
@@ -178,11 +184,10 @@ ego_cb (void *cls, const struct GNUNET_IDENTITY_Ego *ego)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Egos retrieved\n");
     testpeers[1].revok_handle = GNUNET_REVOCATION_revoke (testpeers[1].cfg,
-                                                          &testpeers[1].pubkey,
-                                                          &testpeers[1].sig,
-                                                          testpeers[1].pow,
+                                                          &proof_of_work,
                                                           &revocation_cb,
                                                           NULL);
+    GNUNET_REVOCATION_pow_stop (testpeers[1].pow);
   }
 }
 
diff --git a/src/revocation/test_revocation.conf b/src/revocation/test_revocation.conf
index 3b04150c1..66e2cdcc9 100644
--- a/src/revocation/test_revocation.conf
+++ b/src/revocation/test_revocation.conf
@@ -7,6 +7,7 @@ SERVICEHOME=$GNUNET_TMP/test-revocation-service
 [revocation]
 WORKBITS = 3
 IMMEDIATE_START = YES
+EPOCH_DURATION = 365 d
 
 [identity]
 # Directory where we store information about our egos
diff --git a/src/statistics/gnunet-statistics.c b/src/statistics/gnunet-statistics.c
index 47bdbf2c1..63afde877 100644
--- a/src/statistics/gnunet-statistics.c
+++ b/src/statistics/gnunet-statistics.c
@@ -881,7 +881,7 @@ main (int argc, char *const *argv)
                      num_nodes,
                      0);
   GNUNET_free_non_null (remote_host);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/template/gnunet-template.c b/src/template/gnunet-template.c
index b33cbcc64..5e250bbdf 100644
--- a/src/template/gnunet-template.c
+++ b/src/template/gnunet-template.c
@@ -78,7 +78,7 @@ main (int argc, char *const *argv)
                                           NULL))
         ? ret
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/testbed/gnunet-daemon-latency-logger.c b/src/testbed/gnunet-daemon-latency-logger.c
index 0af718a63..c13750db7 100644
--- a/src/testbed/gnunet-daemon-latency-logger.c
+++ b/src/testbed/gnunet-daemon-latency-logger.c
@@ -317,6 +317,6 @@ main (int argc, char *const *argv)
                          _ (
                            "Daemon to log latency values of connections to neighbours"),
                          options, &run, NULL)) ? 0 : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
diff --git a/src/testbed/gnunet-daemon-testbed-blacklist.c b/src/testbed/gnunet-daemon-testbed-blacklist.c
index 070583941..c82f8075f 100644
--- a/src/testbed/gnunet-daemon-testbed-blacklist.c
+++ b/src/testbed/gnunet-daemon-testbed-blacklist.c
@@ -249,6 +249,6 @@ main (int argc, char *const *argv)
                          _ (
                            "Daemon to restrict incoming transport layer connections during testbed deployments"),
                          options, &run, NULL)) ? 0 : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
diff --git a/src/testbed/gnunet-daemon-testbed-underlay.c b/src/testbed/gnunet-daemon-testbed-underlay.c
index 09dfee5a6..2bff7cdd4 100644
--- a/src/testbed/gnunet-daemon-testbed-underlay.c
+++ b/src/testbed/gnunet-daemon-testbed-underlay.c
@@ -476,6 +476,6 @@ main (int argc, char *const *argv)
                          (
                            "Daemon to restrict underlay network in testbed deployments"),
                          options, &run, NULL)) ? 0 : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
diff --git a/src/testbed/gnunet-testbed-profiler.c b/src/testbed/gnunet-testbed-profiler.c
index cfc6367fe..90813c8e5 100644
--- a/src/testbed/gnunet-testbed-profiler.c
+++ b/src/testbed/gnunet-testbed-profiler.c
@@ -318,7 +318,7 @@ main (int argc, char *const *argv)
   ret =
     GNUNET_PROGRAM_run (argc, argv, "gnunet-testbed-profiler", binaryHelp,
                         options, &run, NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   if (GNUNET_OK != ret)
     return ret;
   if (GNUNET_OK != result)
diff --git a/src/testing/gnunet-testing.c b/src/testing/gnunet-testing.c
index b850d6b13..a9e5042b2 100644
--- a/src/testing/gnunet-testing.c
+++ b/src/testing/gnunet-testing.c
@@ -436,7 +436,7 @@ main (int argc, char *const *argv)
                           GNUNET_YES))
     ? ret
     : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/testing/testing.c b/src/testing/testing.c
index 3e447e1ff..23bc40d7e 100644
--- a/src/testing/testing.c
+++ b/src/testing/testing.c
@@ -1343,7 +1343,7 @@ GNUNET_TESTING_peer_get_identity (struct GNUNET_TESTING_Peer *peer,
     return;
   }
   peer->id = GNUNET_new (struct GNUNET_PeerIdentity);
-  GNUNET_free (
+  GNUNET_free_nz (
     GNUNET_TESTING_hostkey_get (peer->system, peer->key_number, peer->id));
   GNUNET_memcpy (id, peer->id, sizeof(struct GNUNET_PeerIdentity));
 }
diff --git a/src/topology/gnunet-daemon-topology.c b/src/topology/gnunet-daemon-topology.c
index 261d825ea..c6f600df1 100644
--- a/src/topology/gnunet-daemon-topology.c
+++ b/src/topology/gnunet-daemon-topology.c
@@ -1130,7 +1130,7 @@ main (int argc, char *const *argv)
                                           NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/transport/gnunet-communicator-tcp.c b/src/transport/gnunet-communicator-tcp.c
index 82ee309a5..bbfacbffd 100644
--- a/src/transport/gnunet-communicator-tcp.c
+++ b/src/transport/gnunet-communicator-tcp.c
@@ -2285,7 +2285,7 @@ main (int argc, char *const *argv)
                                           NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/transport/gnunet-communicator-udp.c b/src/transport/gnunet-communicator-udp.c
index e0b14f669..72e84567a 100644
--- a/src/transport/gnunet-communicator-udp.c
+++ b/src/transport/gnunet-communicator-udp.c
@@ -2791,7 +2791,7 @@ main (int argc, char *const *argv)
                                           NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/transport/gnunet-communicator-unix.c b/src/transport/gnunet-communicator-unix.c
index 7d7f18a9c..31d2e4ed3 100644
--- a/src/transport/gnunet-communicator-unix.c
+++ b/src/transport/gnunet-communicator-unix.c
@@ -1135,7 +1135,7 @@ main (int argc, char *const *argv)
                              NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/transport/gnunet-transport-profiler.c b/src/transport/gnunet-transport-profiler.c
index 6c13cf059..81678fa20 100644
--- a/src/transport/gnunet-transport-profiler.c
+++ b/src/transport/gnunet-transport-profiler.c
@@ -615,7 +615,7 @@ main (int argc, char *const *argv)
                         options,
                         &run,
                         NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   if (GNUNET_OK == res)
     return ret;
   return 1;
diff --git a/src/transport/gnunet-transport.c b/src/transport/gnunet-transport.c
index 5a437b660..35da5ec10 100644
--- a/src/transport/gnunet-transport.c
+++ b/src/transport/gnunet-transport.c
@@ -1427,7 +1427,7 @@ main (int argc, char *const *argv)
                         options,
                         &run,
                         NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   if (GNUNET_OK == res)
     return ret;
   return 1;
diff --git a/src/transport/tcp_service_legacy.c b/src/transport/tcp_service_legacy.c
index f207863f9..fb4e9c3c9 100644
--- a/src/transport/tcp_service_legacy.c
+++ b/src/transport/tcp_service_legacy.c
@@ -1474,7 +1474,7 @@ shutdown:
   i = 0;
   if (NULL != sctx.addrs)
     while (NULL != sctx.addrs[i])
-      GNUNET_free (sctx.addrs[i++]);
+      GNUNET_free_nz (sctx.addrs[i++]);
   GNUNET_free_non_null (sctx.addrs);
   GNUNET_free_non_null (sctx.addrlens);
   GNUNET_free_non_null (logfile);
@@ -1631,7 +1631,7 @@ LEGACY_SERVICE_stop (struct LEGACY_SERVICE_Context *sctx)
   {
     i = 0;
     while (NULL != sctx->addrs[i])
-      GNUNET_free (sctx->addrs[i++]);
+      GNUNET_free_nz (sctx->addrs[i++]);
     GNUNET_free (sctx->addrs);
   }
   GNUNET_free_non_null (sctx->addrlens);
diff --git a/src/transport/test_plugin_transport.c b/src/transport/test_plugin_transport.c
index 10e07dae5..04687d845 100644
--- a/src/transport/test_plugin_transport.c
+++ b/src/transport/test_plugin_transport.c
@@ -49,7 +49,7 @@ static struct GNUNET_PeerIdentity my_identity;
 /**
  * Our private key.
  */
-static struct GNUNET_CRYPTO_EddsaPrivateKey *my_private_key;
+static struct GNUNET_CRYPTO_EddsaPrivateKey my_private_key;
 
 /**
  * Our configuration.
@@ -647,16 +647,20 @@ run (void *cls,
   }
 
   max_connect_per_transport = (uint32_t) tneigh;
-  my_private_key = GNUNET_CRYPTO_eddsa_key_create_from_file (keyfile);
-  GNUNET_free (keyfile);
-  if (NULL == my_private_key)
+  if (GNUNET_SYSERR ==
+      GNUNET_CRYPTO_eddsa_key_from_file (keyfile,
+                                         GNUNET_YES,
+                                         &my_private_key))
   {
+    GNUNET_free (keyfile);
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 "Could not access hostkey.  Exiting.\n");
     end_badly_now ();
     return;
   }
-  GNUNET_CRYPTO_eddsa_key_get_public (my_private_key, &my_identity.public_key);
+  GNUNET_free (keyfile);
+  GNUNET_CRYPTO_eddsa_key_get_public (&my_private_key,
+                                      &my_identity.public_key);
 
   hello = GNUNET_HELLO_create (&my_identity.public_key, NULL, NULL, GNUNET_NO);
 
diff --git a/src/util/Makefile.am b/src/util/Makefile.am
index ae72abb44..fed0dad79 100644
--- a/src/util/Makefile.am
+++ b/src/util/Makefile.am
@@ -133,6 +133,7 @@ libgnunetutil_la_LIBADD = \
   $(LIBIDN) $(LIBIDN2) \
   $(Z_LIBS) \
   -lunistring \
+  -largon2 \
   $(XLIB) \
   $(PTHREAD)
 
diff --git a/src/util/buffer.c b/src/util/buffer.c
index 8efb3e284..dabf630c7 100644
--- a/src/util/buffer.c
+++ b/src/util/buffer.c
@@ -56,6 +56,8 @@ GNUNET_buffer_ensure_remaining (struct GNUNET_Buffer *buf,
 {
   size_t new_capacity = buf->position + n;
 
+  /* guard against overflow */
+  GNUNET_assert (new_capacity >= buf->position);
   if (new_capacity <= buf->capacity)
     return;
   /* warn if calculation of expected size was wrong */
diff --git a/src/util/crypto_pow.c b/src/util/crypto_pow.c
index 9b20ab345..35511a130 100644
--- a/src/util/crypto_pow.c
+++ b/src/util/crypto_pow.c
@@ -25,7 +25,7 @@
  */
 #include "platform.h"
 #include "gnunet_crypto_lib.h"
-#include <gcrypt.h>
+#include <argon2.h>
 
 /**
  * Calculate the 'proof-of-work' hash (an expensive hash).
@@ -43,81 +43,17 @@ GNUNET_CRYPTO_pow_hash (const char *salt,
                         size_t buf_len,
                         struct GNUNET_HashCode *result)
 {
-#ifdef LSD001
-  char twofish_iv[128 / 8]; //128 bit IV
-  char twofish_key[256 / 8]; //256 bit Key
-  char rbuf[buf_len];
-  int rc;
-  gcry_cipher_hd_t handle;
+  GNUNET_break (ARGON2_OK == argon2d_hash_raw (3, /* iterations */
+                                               1024, /* memory (1 MiB) */
+                                               1, /* threads */
+                                               buf,
+                                               buf_len,
+                                               salt,
+                                               strlen (salt),
+                                               result,
+                                               sizeof (struct
+                                                       GNUNET_HashCode)));
 
-  GNUNET_break (0 == gcry_kdf_derive (buf,
-                                      buf_len,
-                                      GCRY_KDF_SCRYPT,
-                                      1 /* subalgo */,
-                                      salt,
-                                      strlen (salt),
-                                      2 /* iterations; keep cost of individual op small */,
-                                      sizeof(twofish_key),
-                                      &twofish_key));
-
-  GNUNET_CRYPTO_kdf (twofish_iv,
-                     sizeof (twofish_iv),
-                     "gnunet-proof-of-work-iv",
-                     strlen ("gnunet-proof-of-work-iv"),
-                     twofish_key,
-                     sizeof(twofish_key),
-                     salt,
-                     strlen (salt),
-                     NULL, 0);
-  GNUNET_assert (0 ==
-                 gcry_cipher_open (&handle, GCRY_CIPHER_TWOFISH,
-                                   GCRY_CIPHER_MODE_CFB, 0));
-  rc = gcry_cipher_setkey (handle,
-                           twofish_key,
-                           sizeof(twofish_key));
-  GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
-  rc = gcry_cipher_setiv (handle,
-                          twofish_iv,
-                          sizeof(twofish_iv));
-  GNUNET_assert ((0 == rc) || ((char) rc == GPG_ERR_WEAK_KEY));
-  GNUNET_assert (0 == gcry_cipher_encrypt (handle, &rbuf, buf_len, buf, buf_len));
-  gcry_cipher_close (handle);
-#else
-  struct GNUNET_CRYPTO_SymmetricInitializationVector iv;
-  struct GNUNET_CRYPTO_SymmetricSessionKey skey;
-  char rbuf[buf_len];
-
-  GNUNET_break (0 == gcry_kdf_derive (buf,
-                                      buf_len,
-                                      GCRY_KDF_SCRYPT,
-                                      1 /* subalgo */,
-                                      salt,
-                                      strlen (salt),
-                                      2 /* iterations; keep cost of individual op small */,
-                                      sizeof(skey),
-                                      &skey));
-  GNUNET_CRYPTO_symmetric_derive_iv (&iv,
-                                     &skey,
-                                     "gnunet-proof-of-work-iv",
-                                     strlen ("gnunet-proof-of-work-iv"),
-                                     salt,
-                                     strlen (salt),
-                                     NULL, 0);
-  GNUNET_CRYPTO_symmetric_encrypt (buf,
-                                   buf_len,
-                                   &skey,
-                                   &iv,
-                                   &rbuf);
-#endif
-  GNUNET_break (0 == gcry_kdf_derive (rbuf,
-                                      buf_len,
-                                      GCRY_KDF_SCRYPT,
-                                      1 /* subalgo */,
-                                      salt,
-                                      strlen (salt),
-                                      2 /* iterations; keep cost of individual op small */,
-                                      sizeof(struct GNUNET_HashCode),
-                                      result));
 }
 
 
diff --git a/src/util/gnunet-config.c b/src/util/gnunet-config.c
index f101e8b61..5883c1497 100644
--- a/src/util/gnunet-config.c
+++ b/src/util/gnunet-config.c
@@ -331,7 +331,7 @@ main (int argc, char *const *argv)
                         options,
                         &run,
                         NULL);
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   if (GNUNET_OK == ret)
     return global_ret;
   return ret;
diff --git a/src/util/gnunet-ecc.c b/src/util/gnunet-ecc.c
index 764a507b6..8e30ac416 100644
--- a/src/util/gnunet-ecc.c
+++ b/src/util/gnunet-ecc.c
@@ -501,7 +501,7 @@ main (int argc, char *const *argv)
                              NULL))
         ? 0
         : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/util/gnunet-resolver.c b/src/util/gnunet-resolver.c
index 6a602c64e..8a6c7fbe9 100644
--- a/src/util/gnunet-resolver.c
+++ b/src/util/gnunet-resolver.c
@@ -171,14 +171,18 @@ main (int argc, char *const *argv)
   };
   int ret;
 
-  if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args (argc, argv, &argc, &argv))
+  if (GNUNET_OK !=
+      GNUNET_STRINGS_get_utf8_args (argc, argv,
+                                    &argc, &argv))
     return 2;
 
   ret = (GNUNET_OK ==
-         GNUNET_PROGRAM_run (argc, argv, "gnunet-resolver [hostname]",
+         GNUNET_PROGRAM_run (argc, argv,
+                             "gnunet-resolver [hostname]",
                              gettext_noop ("Use build-in GNUnet stub resolver"),
-                             options, &run, NULL)) ? 0 : 1;
-  GNUNET_free ((void *) argv);
+                             options,
+                             &run, NULL)) ? 0 : 1;
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }
 
diff --git a/src/util/gnunet-scrypt.c b/src/util/gnunet-scrypt.c
index 8c46136b9..70ba48d82 100644
--- a/src/util/gnunet-scrypt.c
+++ b/src/util/gnunet-scrypt.c
@@ -322,7 +322,7 @@ main (int argc, char *const *argv)
                          NULL))
     ? 0
     : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   GNUNET_free_non_null (pwfn);
   return ret;
 }
diff --git a/src/util/gnunet-uri.c b/src/util/gnunet-uri.c
index 84100ff56..48c46ee49 100644
--- a/src/util/gnunet-uri.c
+++ b/src/util/gnunet-uri.c
@@ -184,7 +184,7 @@ main (int argc, char *const *argv)
   shc_chld = NULL;
   GNUNET_DISK_pipe_close (sigpipe);
   sigpipe = NULL;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ((GNUNET_OK == ret) && (0 == exit_code)) ? 0 : 1;
 }
 
diff --git a/src/util/os_priority.c b/src/util/os_priority.c
index 36f0d8e30..5799d893b 100644
--- a/src/util/os_priority.c
+++ b/src/util/os_priority.c
@@ -875,7 +875,7 @@ GNUNET_OS_start_process_s (int pipe_control,
                                     binary_path,
                                     argv);
   while (argv_size > 0)
-    GNUNET_free (argv[--argv_size]);
+    GNUNET_free_nz (argv[--argv_size]);
   GNUNET_free (argv);
   return proc;
 }
diff --git a/src/util/scheduler.c b/src/util/scheduler.c
index 45a6b61e5..93393bd7c 100644
--- a/src/util/scheduler.c
+++ b/src/util/scheduler.c
@@ -584,28 +584,26 @@ dump_backtrace (struct GNUNET_SCHEDULER_Task *t)
 static void
 destroy_task (struct GNUNET_SCHEDULER_Task *t)
 {
-  unsigned int i;
-
   LOG (GNUNET_ERROR_TYPE_DEBUG,
        "destroying task %p\n",
        t);
 
   if (GNUNET_YES == t->own_handles)
   {
-    for (i = 0; i != t->fds_len; ++i)
+    for (unsigned int i = 0; i != t->fds_len; ++i)
     {
       const struct GNUNET_NETWORK_Handle *fd = t->fds[i].fd;
       const struct GNUNET_DISK_FileHandle *fh = t->fds[i].fh;
       if (fd)
       {
-        GNUNET_NETWORK_socket_free_memory_only_ ((struct
-                                                  GNUNET_NETWORK_Handle *) fd);
+        GNUNET_NETWORK_socket_free_memory_only_ (
+          (struct GNUNET_NETWORK_Handle *) fd);
       }
       if (fh)
       {
         // FIXME: on WIN32 this is not enough! A function
         // GNUNET_DISK_file_free_memory_only would be nice
-        GNUNET_free ((void *) fh);
+        GNUNET_free_nz ((void *) fh);
       }
     }
   }
diff --git a/src/util/test_common_allocation.c b/src/util/test_common_allocation.c
index e2fc29e82..a24af7124 100644
--- a/src/util/test_common_allocation.c
+++ b/src/util/test_common_allocation.c
@@ -27,7 +27,7 @@
 
 
 static int
-check ()
+check (void)
 {
 #define MAX_TESTVAL 1024
   char *ptrs[MAX_TESTVAL];
@@ -134,6 +134,28 @@ check ()
 }
 
 
+static int
+check2 (void)
+{
+  char *a1 = NULL;
+  unsigned int a1_len = 0;
+  const char *a2 = "test";
+
+  GNUNET_array_append (a1,
+                       a1_len,
+                       'x');
+  GNUNET_array_concatenate (a1,
+                            a1_len,
+                            a2,
+                            4);
+  GNUNET_assert (0 == strncmp ("xtest",
+                               a1,
+                               5));
+  GNUNET_assert (5 == a1_len);
+  return 0;
+}
+
+
 int
 main (int argc, char *argv[])
 {
@@ -142,7 +164,7 @@ main (int argc, char *argv[])
   GNUNET_log_setup ("test-common-allocation",
                     "WARNING",
                     NULL);
-  ret = check ();
+  ret = check () | check2 ();
   if (ret != 0)
     fprintf (stderr,
              "ERROR %d.\n",
diff --git a/src/vpn/gnunet-vpn.c b/src/vpn/gnunet-vpn.c
index 6dcd227c7..a7f7fc30c 100644
--- a/src/vpn/gnunet-vpn.c
+++ b/src/vpn/gnunet-vpn.c
@@ -357,7 +357,7 @@ main (int argc, char *const *argv)
                                       NULL))
     ? ret
     : 1;
-  GNUNET_free ((void *) argv);
+  GNUNET_free_nz ((void *) argv);
   return ret;
 }