sensor: proof-of-work and signing library functions

6 files changed, 360 insertions, 7 deletions

diff --git a/src/include/gnunet_sensor_util_lib.h b/src/include/gnunet_sensor_util_lib.h
index 897fbbaad..d1b1a925e 100644
--- a/src/include/gnunet_sensor_util_lib.h
+++ b/src/include/gnunet_sensor_util_lib.h
@@ -20,7 +20,7 @@
 
 /**
  * @file sensor/sensor_util_lib.c
- * @brief senor utilities
+ * @brief sensor utilities
  * @author Omar Tarabai
  */
 
@@ -210,11 +210,10 @@ struct GNUNET_SENSOR_DashboardAnomalyEntry
 };
 
 GNUNET_NETWORK_STRUCT_BEGIN
-
 /**
  * Used to communicate brief information about a sensor.
  */
-struct GNUNET_SENSOR_SensorBriefMessage
+    struct GNUNET_SENSOR_SensorBriefMessage
 {
 
   /**
@@ -281,7 +280,7 @@ struct GNUNET_SENSOR_SensorFullMessage
  * Used to communicate sensor values to
  * collection points (SENSORDASHBAORD service)
  */
-    struct GNUNET_SENSOR_ValueMessage
+struct GNUNET_SENSOR_ValueMessage
 {
 
   /**
@@ -355,7 +354,6 @@ struct GNUNET_SENSOR_AnomalyReportMessage
 };
 
 GNUNET_NETWORK_STRUCT_END
-
 /**
  * Given two version numbers as major and minor, compare them.
  *
@@ -397,6 +395,79 @@ GNUNET_SENSOR_get_default_sensor_dir ();
 void
 GNUNET_SENSOR_destroy_sensors (struct GNUNET_CONTAINER_MultiHashMap *sensors);
 
+
+struct GNUNET_SENSOR_crypto_pow_context;
+
+/**
+ * Block carrying arbitrary data + its proof-of-work + signature
+ */
+struct GNUNET_SENSOR_crypto_pow_block
+{
+
+  /**
+   * Proof-of-work value
+   */
+  uint64_t pow;
+
+  /**
+   * Data signature
+   */
+  struct GNUNET_CRYPTO_EddsaSignature signature;
+
+  /**
+   * Purpose of signing, data is allocated after this.
+   */
+  struct GNUNET_CRYPTO_EccSignaturePurpose purpose;
+
+};
+
+
+/**
+ * Continuation called with a status result.
+ *
+ * @param cls closure
+ * @param pow Proof-of-work value
+ * @param purpose Signed block (size, purpose, data)
+ * @param signature Signature, NULL on error
+ */
+typedef void (*GNUNET_SENSOR_UTIL_pow_callback) (void *cls,
+                                                 struct
+                                                 GNUNET_SENSOR_crypto_pow_block
+                                                 * block);
+
+
+/**
+ * Cancel an operation started by #GNUNET_SENSOR_crypto_pow_sign().
+ * Call only before callback function passed to #GNUNET_SENSOR_crypto_pow_sign()
+ * is called with the result.
+ */
+void
+GNUNET_SENSOR_crypto_pow_sign_cancel (struct GNUNET_SENSOR_crypto_pow_context
+                                      *cx);
+
+
+/**
+ * Calculate proof-of-work and sign a message.
+ *
+ * @param msg Message to calculate pow and sign
+ * @param msg_size size of msg
+ * @param timestamp Timestamp to add to the message to protect against replay attacks
+ * @param public_key Public key of the origin peer, to protect against redirect attacks
+ * @param private_key Private key of the origin peer to sign the result
+ * @param matching_bits Number of leading zeros required in the result hash
+ * @param callback Callback function to call with the result
+ * @param callback_cls Closure for callback
+ * @return Operation context
+ */
+struct GNUNET_SENSOR_crypto_pow_context *
+GNUNET_SENSOR_crypto_pow_sign (void *msg, size_t msg_size,
+                               struct GNUNET_TIME_Absolute *timestamp,
+                               struct GNUNET_CRYPTO_EddsaPublicKey *public_key,
+                               struct GNUNET_CRYPTO_EddsaPrivateKey
+                               *private_key, int matching_bits,
+                               GNUNET_SENSOR_UTIL_pow_callback callback,
+                               void *callback_cls);
+
 #if 0                           /* keep Emacsens' auto-indent happy */
 {
 #endif
diff --git a/src/include/gnunet_signatures.h b/src/include/gnunet_signatures.h
index a2a41a256..5c1abb5ff 100644
--- a/src/include/gnunet_signatures.h
+++ b/src/include/gnunet_signatures.h
@@ -171,6 +171,11 @@ extern "C"
  */
 #define GNUNET_SIGNATURE_PURPOSE_MULTICAST_REQUEST 24
 
+/**
+ * Signature for a sensor anomaly report message.
+ */
+#define GNUNET_SIGNATURE_PURPOSE_SENSOR_ANOMALY_REPORT 25
+
 
 #if 0                           /* keep Emacsens' auto-indent happy */
 {
diff --git a/src/sensor/Makefile.am b/src/sensor/Makefile.am
index 305b91aad..d6577ee63 100644
--- a/src/sensor/Makefile.am
+++ b/src/sensor/Makefile.am
@@ -57,7 +57,8 @@ libgnunetsensor_la_LDFLAGS = \
   $(GN_LIB_LDFLAGS)
 
 libgnunetsensorutil_la_SOURCES = \
-  sensor_util_lib.c
+  sensor_util_lib.c \
+  sensor_util_lib_crypto.c
 libgnunetsensorutil_la_LIBADD = \
   $(top_builddir)/src/util/libgnunetutil.la \
   $(top_builddir)/src/statistics/libgnunetstatistics.la
diff --git a/src/sensor/gnunet-service-sensor_reporting.c b/src/sensor/gnunet-service-sensor_reporting.c
index 6267e9f2a..562768ff1 100644
--- a/src/sensor/gnunet-service-sensor_reporting.c
+++ b/src/sensor/gnunet-service-sensor_reporting.c
@@ -607,6 +607,9 @@ handle_anomaly_report (void *cls, const struct GNUNET_PeerIdentity *other,
       GNUNET_CONTAINER_multipeermap_contains
       (my_anomaly_info->anomalous_neighbors, other);
   peer_anomalous = ntohs (arm->anomalous);
+  LOG (GNUNET_ERROR_TYPE_DEBUG,
+       "Received an anomaly update from neighbour `%s' (%d).\n",
+       GNUNET_i2s (other), peer_anomalous);
   if (GNUNET_YES == peer_anomalous)
   {
     if (GNUNET_YES == peer_in_anomalous_list)   /* repeated positive report */
diff --git a/src/sensor/sensor_util_lib.c b/src/sensor/sensor_util_lib.c
index 136bb288a..d3ed8c408 100644
--- a/src/sensor/sensor_util_lib.c
+++ b/src/sensor/sensor_util_lib.c
@@ -20,7 +20,7 @@
 
 /**
  * @file sensor/sensor_util_lib.c
- * @brief senor utilities
+ * @brief sensor utilities
  * @author Omar Tarabai
  */
 #include <inttypes.h>
diff --git a/src/sensor/sensor_util_lib_crypto.c b/src/sensor/sensor_util_lib_crypto.c
new file mode 100644
index 000000000..bccbe74f9
--- /dev/null
+++ b/src/sensor/sensor_util_lib_crypto.c
@@ -0,0 +1,273 @@
+/*
+     This file is part of GNUnet.
+     (C)
+
+     GNUnet is free software; you can redistribute it and/or modify
+     it under the terms of the GNU General Public License as published
+     by the Free Software Foundation; either version 3, or (at your
+     option) any later version.
+
+     GNUnet is distributed in the hope that it will be useful, but
+     WITHOUT ANY WARRANTY; without even the implied warranty of
+     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+     Boston, MA 02111-1307, USA.
+*/
+
+/**
+ * @file sensor/sensor_util_lib_crypto.c
+ * @brief senor utilities - crpyto related functions
+ * @author Omar Tarabai
+ */
+
+#include "platform.h"
+#include "gnunet_util_lib.h"
+#include "gnunet_sensor_util_lib.h"
+#include "gnunet_signatures.h"
+
+#define LOG(kind,...) GNUNET_log_from (kind, "sensor-util-crypto",__VA_ARGS__)
+
+/**
+ * Context of an operation performed by #GNUNET_SENSOR_crypto_pow_sign()
+ */
+struct GNUNET_SENSOR_crypto_pow_context
+{
+
+  /**
+   * Buffer of the complete message to calculate the pow for
+   */
+  void *buf;
+
+  /**
+   * Size of buf
+   */
+  size_t buf_size;
+
+  /**
+   * Proof-of-work number
+   */
+  uint64_t pow;
+
+  /**
+   * Private key to be used for signing
+   */
+  struct GNUNET_CRYPTO_EddsaPrivateKey private_key;
+
+  /**
+   * Number of leading zeros required in the result hash
+   */
+  int matching_bits;
+
+  /**
+   * Callback function to call with the result
+   */
+  GNUNET_SENSOR_UTIL_pow_callback callback;
+
+  /**
+   * Closure for callback
+   */
+  void *callback_cls;
+
+  /**
+   * Task that calculates the proof-of-work
+   */
+  GNUNET_SCHEDULER_TaskIdentifier calculate_pow_task;
+
+};
+
+
+/**
+ * Calculate the scrypt hash
+ */
+static void
+pow_hash (const void *buf, size_t buf_len, struct GNUNET_HashCode *result)
+{
+  GNUNET_break (0 ==
+                gcry_kdf_derive (buf, buf_len, GCRY_KDF_SCRYPT,
+                                 1 /* subalgo */ ,
+                                 "gnunet-sensor-util-proof-of-work",
+                                 strlen ("gnunet-sensor-util-proof-of-work"), 2
+                                 /* iterations; keep cost of individual op small */
+                                 , sizeof (struct GNUNET_HashCode), result));
+}
+
+
+/**
+ * Count the leading zeroes in hash.
+ *
+ * @param hash to count leading zeros in
+ * @return the number of leading zero bits.
+ */
+static unsigned int
+count_leading_zeroes (const struct GNUNET_HashCode *hash)
+{
+  unsigned int hash_count;
+
+  hash_count = 0;
+  while ((0 == GNUNET_CRYPTO_hash_get_bit (hash, hash_count)))
+    hash_count++;
+  return hash_count;
+}
+
+
+/**
+ * Check if the given proof-of-work is valid
+ */
+static int
+check_pow (void *msg, size_t msg_size, uint64_t pow, int matching_bits)
+{
+  char buf[msg_size + sizeof (pow)] GNUNET_ALIGN;
+  struct GNUNET_HashCode result;
+
+  memcpy (buf, &pow, sizeof (pow));
+  memcpy (&buf[sizeof (pow)], msg, msg_size);
+  pow_hash (buf, sizeof (buf), &result);
+  return (count_leading_zeroes (&result) >=
+          matching_bits) ? GNUNET_YES : GNUNET_NO;
+}
+
+
+/**
+ * Task that checks if pow is correct, otherwise increments and reschedules itself
+ */
+static void
+calculate_pow (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
+{
+  struct GNUNET_SENSOR_crypto_pow_context *cx = cls;
+  struct GNUNET_SENSOR_crypto_pow_block *result_block;
+  GNUNET_SENSOR_UTIL_pow_callback callback;
+  void *callback_cls;
+  int sign_result;
+
+  if (GNUNET_YES ==
+      check_pow (cx->buf, cx->buf_size, cx->pow, cx->matching_bits))
+  {
+    cx->calculate_pow_task = GNUNET_SCHEDULER_NO_TASK;
+    result_block =
+        GNUNET_malloc (sizeof (struct GNUNET_SENSOR_crypto_pow_block) +
+                       cx->buf_size);
+    result_block->purpose.purpose =
+        GNUNET_SIGNATURE_PURPOSE_SENSOR_ANOMALY_REPORT;
+    result_block->purpose.size =
+        sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose) + cx->buf_size;
+    memcpy (&result_block[1], cx->buf, cx->buf_size);
+    sign_result =
+        GNUNET_CRYPTO_eddsa_sign (&cx->private_key, &result_block->purpose,
+                                  &result_block->signature);
+    callback = cx->callback;
+    callback_cls = cx->callback_cls;
+    GNUNET_SENSOR_crypto_pow_sign_cancel (cx);
+    if (NULL != callback)
+      callback (callback_cls, (GNUNET_OK == sign_result) ? result_block : NULL);
+  }
+  cx->pow++;
+  cx->calculate_pow_task = GNUNET_SCHEDULER_add_now (&calculate_pow, cx);
+}
+
+
+/**
+ * Cancel an operation started by #GNUNET_SENSOR_crypto_pow_sign().
+ * Call only before callback function passed to #GNUNET_SENSOR_crypto_pow_sign()
+ * is called with the result.
+ */
+void
+GNUNET_SENSOR_crypto_pow_sign_cancel (struct GNUNET_SENSOR_crypto_pow_context
+                                      *cx)
+{
+  if (NULL != cx->buf)
+  {
+    GNUNET_free (cx->buf);
+    cx->buf = NULL;
+  }
+  GNUNET_free (cx);
+}
+
+
+/**
+ * Calculate proof-of-work and sign a message.
+ * The result of all operations will be returned via the callback passed to this
+ * function. Note that the payload (msg) is copied to the result block.
+ *
+ * @param msg Message to calculate pow and sign
+ * @param msg_size size of msg
+ * @param timestamp Timestamp to add to the message to protect against replay attacks
+ * @param public_key Public key of the origin peer, to protect against redirect attacks
+ * @param private_key Private key of the origin peer to sign the result
+ * @param matching_bits Number of leading zeros required in the result hash
+ * @param callback Callback function to call with the result
+ * @param callback_cls Closure for callback
+ * @return Operation context
+ */
+struct GNUNET_SENSOR_crypto_pow_context *
+GNUNET_SENSOR_crypto_pow_sign (void *msg, size_t msg_size,
+                               struct GNUNET_TIME_Absolute *timestamp,
+                               struct GNUNET_CRYPTO_EddsaPublicKey *public_key,
+                               struct GNUNET_CRYPTO_EddsaPrivateKey
+                               *private_key, int matching_bits,
+                               GNUNET_SENSOR_UTIL_pow_callback callback,
+                               void *callback_cls)
+{
+  struct GNUNET_SENSOR_crypto_pow_context *cx;
+  void *buf;
+  size_t buf_size;
+
+  buf_size = msg_size + sizeof (*timestamp) + sizeof (*public_key);
+  buf = GNUNET_malloc (buf_size);
+  cx = GNUNET_new (struct GNUNET_SENSOR_crypto_pow_context);
+
+  cx->buf = buf;
+  cx->buf_size = buf_size;
+  cx->pow = 0;
+  cx->private_key = *private_key;
+  cx->matching_bits = matching_bits;
+  cx->callback = callback;
+  cx->callback_cls = callback_cls;
+  cx->calculate_pow_task = GNUNET_SCHEDULER_add_now (&calculate_pow, cx);
+  return cx;
+}
+
+
+/**
+ * Verify that proof-of-work and signature in the given block are valid.
+ * If all valid, a pointer to the payload within the block is set and the size
+ * of the payload is returned.
+ *
+ * @param block The block received and needs to be verified
+ * @param matching_bits Number of leading zeros in the hash used to verify pow
+ * @param public_key Public key of the peer that sent this block
+ * @param payload Where to store the pointer to the payload
+ * @return Size of the payload
+ */
+size_t
+GNUNET_SENSOR_crypto_verify_pow_sign (struct GNUNET_SENSOR_crypto_pow_block *
+                                      block, int matching_bits,
+                                      struct GNUNET_CRYPTO_EddsaPublicKey *
+                                      public_key, void **payload)
+{
+  void *msg;
+  size_t msg_size;
+
+  /* Check signature */
+  if (GNUNET_OK !=
+      GNUNET_CRYPTO_eddsa_verify (block->purpose.purpose, &block->purpose,
+                                  &block->signature, public_key))
+  {
+    LOG (GNUNET_ERROR_TYPE_WARNING, "Invalid signature.\n");
+    return 0;
+  }
+  /* Check pow */
+  msg = &block[1];
+  msg_size =
+      block->purpose.size - sizeof (struct GNUNET_CRYPTO_EccSignaturePurpose);
+  if (GNUNET_NO == check_pow (msg, msg_size, block->pow, matching_bits))
+  {
+    LOG (GNUNET_ERROR_TYPE_WARNING, "Invalid proof-of-work.\n");
+    return 0;
+  }
+  *payload = msg;
+  return msg_size;
+}