1 files changed, 132 insertions, 0 deletions

diff --git a/src/util/crypto_mpi.c b/src/util/crypto_mpi.c
new file mode 100644
index 000000000..8e52424cf
--- /dev/null
+++ b/src/util/crypto_mpi.c
@@ -0,0 +1,132 @@
+/*
+     This file is part of GNUnet.
+     (C) 2012, 2013 Christian Grothoff (and other contributing authors)
+
+     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 util/crypto_mpi.c
+ * @brief Helper functions for libgcrypt MPIs
+ * @author Christian Grothoff
+ * @author Florian Dold
+ */
+#include "platform.h"
+#include <gcrypt.h>
+#include "gnunet_util_lib.h"
+
+
+#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
+
+/**
+ * Log an error message at log-level 'level' that indicates
+ * a failure of the command 'cmd' with the message given
+ * by gcry_strerror(rc).
+ */
+#define LOG_GCRY(level, cmd, rc) do { LOG(level, _("`%s' failed at %s:%d with error: %s\n"), cmd, __FILE__, __LINE__, gcry_strerror(rc)); } while(0)
+
+
+/**
+ * If target != size, move @a target bytes to the end of the size-sized
+ * buffer and zero out the first @a target - @a size bytes.
+ *
+ * @param buf original buffer
+ * @param size number of bytes in @a buf
+ * @param target target size of the buffer
+ */
+static void
+adjust (void *buf,
+        size_t size,
+        size_t target)
+{
+  if (size < target)
+  {
+    memmove (&buf[target - size], buf, size);
+    memset (buf, 0, target - size);
+  }
+}
+
+
+/**
+ * Output the given MPI value to the given buffer in
+ * network byte order.
+ * The MPI @a val may not be negative.
+ *
+ * @param buf where to output to
+ * @param size number of bytes in @a buf
+ * @param val value to write to @a buf
+ */
+void
+GNUNET_CRYPTO_mpi_print_unsigned (void *buf,
+                                  size_t size,
+                                  gcry_mpi_t val)
+{
+  size_t rsize;
+
+  if (gcry_mpi_get_flag (val, GCRYMPI_FLAG_OPAQUE))
+  {
+    /* Store opaque MPIs left aligned into the buffer.  */
+    unsigned int nbits;
+    const void *p;
+
+    p = gcry_mpi_get_opaque (val, &nbits);
+    GNUNET_assert (p);
+    rsize = (nbits+7)/8;
+    if (rsize > size)
+      rsize = size;
+    memcpy (buf, p, rsize);
+    if (rsize < size)
+      memset (buf+rsize, 0, size - rsize);
+  }
+  else
+  {
+    /* Store regular MPIs as unsigned integers right aligned into
+       the buffer.  */
+    rsize = size;
+    GNUNET_assert (0 ==
+                   gcry_mpi_print (GCRYMPI_FMT_USG, buf, rsize, &rsize,
+                                   val));
+    adjust (buf, rsize, size);
+  }
+}
+
+
+/**
+ * Convert data buffer into MPI value.
+ * The buffer is interpreted as network
+ * byte order, unsigned integer.
+ *
+ * @param result where to store MPI value (allocated)
+ * @param data raw data (GCRYMPI_FMT_USG)
+ * @param size number of bytes in @a data
+ */
+void
+GNUNET_CRYPTO_mpi_scan_unsigned (gcry_mpi_t *result,
+                                 const void *data,
+                                 size_t size)
+{
+  int rc;
+
+  if (0 != (rc = gcry_mpi_scan (result,
+                                GCRYMPI_FMT_USG,
+                                data, size, &size)))
+  {
+    LOG_GCRY (GNUNET_ERROR_TYPE_ERROR, "gcry_mpi_scan", rc);
+    GNUNET_assert (0);
+  }
+}
+
+/* end of crypto_mpi.c */