1 files changed, 136 insertions, 0 deletions

diff --git a/src/util/crypto_random.c b/src/util/crypto_random.c
new file mode 100644
index 000000000..3f7ac4dd3
--- /dev/null
+++ b/src/util/crypto_random.c
@@ -0,0 +1,136 @@
+/*
+     This file is part of GNUnet.
+     (C) 2001, 2002, 2003, 2004, 2005, 2006 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 2, 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_random.c
+ * @brief functions to gather random numbers
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include "gnunet_common.h"
+#include "gnunet_crypto_lib.h"
+#include <gcrypt.h>
+
+/**
+ * @return a random value in the interval [0,i[.
+ */
+unsigned int
+GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, unsigned int i)
+{
+#ifdef gcry_fast_random_poll
+  static unsigned int invokeCount;
+#endif
+  unsigned int ret;
+
+  GNUNET_assert (i > 0);
+
+  if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
+    {
+      /* see http://lists.gnupg.org/pipermail/gcrypt-devel/2004-May/000613.html */
+#ifdef gcry_fast_random_poll
+      if ((invokeCount++ % 256) == 0)
+        gcry_fast_random_poll ();
+#endif
+      ret = rand ();            /* in case gcry_randomize fails,
+                                   we at least get a pseudo-
+                                   random number this way */
+      gcry_randomize ((unsigned char *) &ret,
+                      sizeof (unsigned int), GCRY_STRONG_RANDOM);
+      return ret % i;
+    }
+  else
+    {
+      ret = i * ((double) RANDOM () / RAND_MAX);
+      if (ret >= i)
+        ret = i - 1;
+      return ret;
+    }
+}
+
+
+/**
+ * Get an array with a random permutation of the
+ * numbers 0...n-1.
+ * @param mode GNUNET_RANDOM_QUALITY_STRONG if the strong (but expensive)
+ *        PRNG should be used, GNUNET_RANDOM_QUALITY_WEAK otherwise
+ * @param n the size of the array
+ * @return the permutation array (allocated from heap)
+ */
+unsigned int *
+GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
+{
+  unsigned int *ret;
+  unsigned int i;
+  unsigned int tmp;
+  unsigned int x;
+
+  GNUNET_assert (n > 0);
+  ret = GNUNET_malloc (n * sizeof (int));
+  for (i = 0; i < n; i++)
+    ret[i] = i;
+  for (i = 0; i < n; i++)
+    {
+      x = GNUNET_CRYPTO_random_u32 (mode, n);
+      tmp = ret[x];
+      ret[x] = ret[i];
+      ret[i] = tmp;
+    }
+  return ret;
+}
+
+/**
+ * Random on unsigned 64-bit values.
+ */
+unsigned long long
+GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode,
+                          unsigned long long u)
+{
+  unsigned long long ret;
+
+  GNUNET_assert (u > 0);
+  if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
+    {
+      gcry_randomize ((unsigned char *) &ret,
+                      sizeof (unsigned long long), GCRY_STRONG_RANDOM);
+      return ret % u;
+    }
+  else
+    {
+      ret = u * ((double) RANDOM () / RAND_MAX);
+      if (ret >= u)
+        ret = u - 1;
+      return ret;
+    }
+}
+
+/**
+ * This function should only be called in testcases
+ * where strong entropy gathering is not desired
+ * (for example, for hostkey generation).
+ */
+void
+GNUNET_CRYPTO_random_disable_entropy_gathering ()
+{
+  gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
+}
+
+
+/* end of crypto_random.c */