1 files changed, 178 insertions, 0 deletions

diff --git a/src/lib/util/crypto_mpi.c b/src/lib/util/crypto_mpi.c
new file mode 100644
index 000000000..06f2fd786
--- /dev/null
+++ b/src/lib/util/crypto_mpi.c
@@ -0,0 +1,178 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2012, 2013 GNUnet e.V.
+
+     GNUnet is free software: you can redistribute it and/or modify it
+     under the terms of the GNU Affero General Public License as published
+     by the Free Software Foundation, either version 3 of the License,
+     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
+     Affero General Public License for more details.
+
+     You should have received a copy of the GNU Affero General Public License
+     along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+     SPDX-License-Identifier: AGPL3.0-or-later
+ */
+
+/**
+ * @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-crypto-mpi", __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)
+{
+  char *p = buf;
+
+  if (size < target)
+  {
+    memmove (&p[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;
+  int rc;
+
+  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;
+    GNUNET_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;
+    if (0 !=
+        (rc = gcry_mpi_print (GCRYMPI_FMT_USG,
+                              buf,
+                              rsize, &rsize,
+                              val)))
+    {
+      LOG_GCRY (GNUNET_ERROR_TYPE_ERROR,
+                "gcry_mpi_print",
+                rc);
+      GNUNET_assert (0);
+    }
+    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);
+  }
+}
+
+
+/**
+ * Convert little endian 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_le (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 */