added MirOTR

git-svn-id: http://svn.miranda-ng.org/main/trunk@83 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c

1 files changed, 1862 insertions, 0 deletions

diff --git a/plugins/MirOTR/libgcrypt-1.4.6/cipher/primegen.c b/plugins/MirOTR/libgcrypt-1.4.6/cipher/primegen.c
new file mode 100644
index 0000000000..b869bee839
--- /dev/null
+++ b/plugins/MirOTR/libgcrypt-1.4.6/cipher/primegen.c
@@ -0,0 +1,1862 @@
+/* primegen.c - prime number generator
+ * Copyright (C) 1998, 2000, 2001, 2002, 2003
+ *               2004, 2008 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser general Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include "g10lib.h"
+#include "mpi.h"
+#include "cipher.h"
+#include "ath.h"
+
+static gcry_mpi_t gen_prime (unsigned int nbits, int secret, int randomlevel, 
+                             int (*extra_check)(void *, gcry_mpi_t),
+                             void *extra_check_arg);
+static int check_prime( gcry_mpi_t prime, gcry_mpi_t val_2, int rm_rounds,
+                        gcry_prime_check_func_t cb_func, void *cb_arg );
+static int is_prime (gcry_mpi_t n, int steps, unsigned int *count);
+static void m_out_of_n( char *array, int m, int n );
+
+static void (*progress_cb) (void *,const char*,int,int, int );
+static void *progress_cb_data;
+
+/* Note: 2 is not included because it can be tested more easily by
+   looking at bit 0. The last entry in this list is marked by a zero */
+static ushort small_prime_numbers[] = {
+    3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43,
+    47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101,
+    103, 107, 109, 113, 127, 131, 137, 139, 149, 151,
+    157, 163, 167, 173, 179, 181, 191, 193, 197, 199,
+    211, 223, 227, 229, 233, 239, 241, 251, 257, 263,
+    269, 271, 277, 281, 283, 293, 307, 311, 313, 317,
+    331, 337, 347, 349, 353, 359, 367, 373, 379, 383,
+    389, 397, 401, 409, 419, 421, 431, 433, 439, 443,
+    449, 457, 461, 463, 467, 479, 487, 491, 499, 503,
+    509, 521, 523, 541, 547, 557, 563, 569, 571, 577,
+    587, 593, 599, 601, 607, 613, 617, 619, 631, 641,
+    643, 647, 653, 659, 661, 673, 677, 683, 691, 701,
+    709, 719, 727, 733, 739, 743, 751, 757, 761, 769,
+    773, 787, 797, 809, 811, 821, 823, 827, 829, 839,
+    853, 857, 859, 863, 877, 881, 883, 887, 907, 911,
+    919, 929, 937, 941, 947, 953, 967, 971, 977, 983,
+    991, 997, 1009, 1013, 1019, 1021, 1031, 1033,
+    1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091,
+    1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151,
+    1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213,
+    1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277,
+    1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307,
+    1319, 1321, 1327, 1361, 1367, 1373, 1381, 1399,
+    1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451,
+    1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493,
+    1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559,
+    1567, 1571, 1579, 1583, 1597, 1601, 1607, 1609,
+    1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667,
+    1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733,
+    1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789,
+    1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871,
+    1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931,
+    1933, 1949, 1951, 1973, 1979, 1987, 1993, 1997,
+    1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053,
+    2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111,
+    2113, 2129, 2131, 2137, 2141, 2143, 2153, 2161,
+    2179, 2203, 2207, 2213, 2221, 2237, 2239, 2243,
+    2251, 2267, 2269, 2273, 2281, 2287, 2293, 2297,
+    2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357,
+    2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411,
+    2417, 2423, 2437, 2441, 2447, 2459, 2467, 2473,
+    2477, 2503, 2521, 2531, 2539, 2543, 2549, 2551,
+    2557, 2579, 2591, 2593, 2609, 2617, 2621, 2633,
+    2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687,
+    2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729,
+    2731, 2741, 2749, 2753, 2767, 2777, 2789, 2791,
+    2797, 2801, 2803, 2819, 2833, 2837, 2843, 2851,
+    2857, 2861, 2879, 2887, 2897, 2903, 2909, 2917,
+    2927, 2939, 2953, 2957, 2963, 2969, 2971, 2999,
+    3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061,
+    3067, 3079, 3083, 3089, 3109, 3119, 3121, 3137,
+    3163, 3167, 3169, 3181, 3187, 3191, 3203, 3209,
+    3217, 3221, 3229, 3251, 3253, 3257, 3259, 3271,
+    3299, 3301, 3307, 3313, 3319, 3323, 3329, 3331,
+    3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391,
+    3407, 3413, 3433, 3449, 3457, 3461, 3463, 3467,
+    3469, 3491, 3499, 3511, 3517, 3527, 3529, 3533,
+    3539, 3541, 3547, 3557, 3559, 3571, 3581, 3583,
+    3593, 3607, 3613, 3617, 3623, 3631, 3637, 3643,
+    3659, 3671, 3673, 3677, 3691, 3697, 3701, 3709,
+    3719, 3727, 3733, 3739, 3761, 3767, 3769, 3779,
+    3793, 3797, 3803, 3821, 3823, 3833, 3847, 3851,
+    3853, 3863, 3877, 3881, 3889, 3907, 3911, 3917,
+    3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989,
+    4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049,
+    4051, 4057, 4073, 4079, 4091, 4093, 4099, 4111,
+    4127, 4129, 4133, 4139, 4153, 4157, 4159, 4177,
+    4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243,
+    4253, 4259, 4261, 4271, 4273, 4283, 4289, 4297,
+    4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391,
+    4397, 4409, 4421, 4423, 4441, 4447, 4451, 4457,
+    4463, 4481, 4483, 4493, 4507, 4513, 4517, 4519,
+    4523, 4547, 4549, 4561, 4567, 4583, 4591, 4597,
+    4603, 4621, 4637, 4639, 4643, 4649, 4651, 4657,
+    4663, 4673, 4679, 4691, 4703, 4721, 4723, 4729,
+    4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799,
+    4801, 4813, 4817, 4831, 4861, 4871, 4877, 4889,
+    4903, 4909, 4919, 4931, 4933, 4937, 4943, 4951,
+    4957, 4967, 4969, 4973, 4987, 4993, 4999,
+    0
+};
+static int no_of_small_prime_numbers = DIM (small_prime_numbers) - 1;
+
+
+
+/* An object and a list to build up a global pool of primes.  See
+   save_pool_prime and get_pool_prime. */
+struct primepool_s 
+{
+  struct primepool_s *next;
+  gcry_mpi_t prime;      /* If this is NULL the entry is not used. */
+  unsigned int nbits;
+  gcry_random_level_t randomlevel;
+};
+struct primepool_s *primepool;
+/* Mutex used to protect access to the primepool.  */
+static ath_mutex_t primepool_lock = ATH_MUTEX_INITIALIZER;
+
+
+
+/* Save PRIME which has been generated at RANDOMLEVEL for later
+   use. Needs to be called while primepool_lock is being hold.  Note
+   that PRIME should be considered released after calling this
+   function. */
+static void
+save_pool_prime (gcry_mpi_t prime, gcry_random_level_t randomlevel)
+{
+  struct primepool_s *item, *item2;
+  size_t n;
+
+  for (n=0, item = primepool; item; item = item->next, n++)
+    if (!item->prime)
+      break;
+  if (!item && n > 100)
+    {
+      /* Remove some of the entries.  Our strategy is removing
+         the last third from the list. */
+      int i;
+      
+      for (i=0, item2 = primepool; item2; item2 = item2->next)
+        {
+          if (i >= n/3*2)
+            {
+              gcry_mpi_release (item2->prime);
+              item2->prime = NULL;
+              if (!item)
+                item = item2;
+            }
+        }
+    }
+  if (!item)
+    {
+      item = gcry_calloc (1, sizeof *item);
+      if (!item)
+        {
+          /* Out of memory.  Silently giving up. */
+          gcry_mpi_release (prime);
+          return; 
+        }
+      item->next = primepool;
+      primepool = item;
+    }
+  item->prime = prime;
+  item->nbits = mpi_get_nbits (prime);
+  item->randomlevel = randomlevel;
+}
+
+
+/* Return a prime for the prime pool or NULL if none has been found.
+   The prime needs to match NBITS and randomlevel. This function needs
+   to be called why the primepool_look is being hold. */
+static gcry_mpi_t
+get_pool_prime (unsigned int nbits, gcry_random_level_t randomlevel)
+{
+  struct primepool_s *item;
+
+  for (item = primepool; item; item = item->next)
+    if (item->prime
+        && item->nbits == nbits && item->randomlevel == randomlevel)
+      {
+        gcry_mpi_t prime = item->prime;
+        item->prime = NULL;
+        gcry_assert (nbits == mpi_get_nbits (prime));
+        return prime;
+      }
+  return NULL;
+}
+
+
+
+
+
+
+void
+_gcry_register_primegen_progress ( void (*cb)(void *,const char*,int,int,int),
+                                   void *cb_data )
+{
+  progress_cb = cb;
+  progress_cb_data = cb_data;
+}
+
+
+static void
+progress( int c )
+{
+  if ( progress_cb )
+    progress_cb ( progress_cb_data, "primegen", c, 0, 0 );
+}
+
+
+/****************
+ * Generate a prime number (stored in secure memory)
+ */
+gcry_mpi_t
+_gcry_generate_secret_prime (unsigned int nbits,
+                             gcry_random_level_t random_level,
+                             int (*extra_check)(void*, gcry_mpi_t),
+                             void *extra_check_arg)
+{
+  gcry_mpi_t prime;
+
+  prime = gen_prime (nbits, 1, random_level, extra_check, extra_check_arg);
+  progress('\n');
+  return prime;
+}
+
+
+/* Generate a prime number which may be public, i.e. not allocated in
+   secure memory.  */
+gcry_mpi_t
+_gcry_generate_public_prime (unsigned int nbits,
+                             gcry_random_level_t random_level,
+                             int (*extra_check)(void*, gcry_mpi_t),
+                             void *extra_check_arg)
+{
+  gcry_mpi_t prime;
+
+  prime = gen_prime (nbits, 0, random_level, extra_check, extra_check_arg);
+  progress('\n');
+  return prime;
+}
+
+
+/* Core prime generation function.  The algorithm used to generate
+   practically save primes is due to Lim and Lee as described in the
+   CRYPTO '97 proceedings (ISBN3540633847) page 260.
+
+   NEED_Q_FACTOR: If true make sure that at least one factor is of
+                  size qbits.  This is for example required for DSA.
+   PRIME_GENERATED: Adresss of a variable where the resulting prime
+                    number will be stored.
+   PBITS: Requested size of the prime number.  At least 48.
+   QBITS: One factor of the prime needs to be of this size.  Maybe 0
+          if this is not required.  See also MODE.
+   G: If not NULL an MPI which will receive a generator for the prime
+      for use with Elgamal.
+   RET_FACTORS: if not NULL, an array with all factors are stored at
+                that address.
+   ALL_FACTORS: If set to true all factors of prime-1 are returned.
+   RANDOMLEVEL:  How strong should the random numers be.
+   FLAGS: Prime generation bit flags. Currently supported:
+          GCRY_PRIME_FLAG_SECRET - The prime needs to be kept secret.
+   CB_FUNC, CB_ARG:  Callback to be used for extra checks.
+
+ */
+static gcry_err_code_t
+prime_generate_internal (int need_q_factor,
+			 gcry_mpi_t *prime_generated, unsigned int pbits,
+			 unsigned int qbits, gcry_mpi_t g,
+			 gcry_mpi_t **ret_factors,
+			 gcry_random_level_t randomlevel, unsigned int flags,
+                         int all_factors,
+                         gcry_prime_check_func_t cb_func, void *cb_arg)
+{
+  gcry_err_code_t err = 0;
+  gcry_mpi_t *factors_new = NULL; /* Factors to return to the
+				     caller.  */
+  gcry_mpi_t *factors = NULL;	/* Current factors.  */
+  gcry_random_level_t poolrandomlevel; /* Random level used for pool primes. */
+  gcry_mpi_t *pool = NULL;	/* Pool of primes.  */
+  int *pool_in_use = NULL;      /* Array with currently used POOL elements. */
+  unsigned char *perms = NULL;	/* Permutations of POOL.  */
+  gcry_mpi_t q_factor = NULL;	/* Used if QBITS is non-zero.  */
+  unsigned int fbits = 0;	/* Length of prime factors.  */
+  unsigned int n = 0;		/* Number of factors.  */
+  unsigned int m = 0;		/* Number of primes in pool.  */
+  gcry_mpi_t q = NULL;		/* First prime factor.  */
+  gcry_mpi_t prime = NULL;	/* Prime candidate.  */
+  unsigned int nprime = 0;	/* Bits of PRIME.  */
+  unsigned int req_qbits;       /* The original QBITS value.  */
+  gcry_mpi_t val_2;             /* For check_prime().  */
+  int is_locked = 0;            /* Flag to help unlocking the primepool. */
+  unsigned int is_secret = (flags & GCRY_PRIME_FLAG_SECRET);
+  unsigned int count1 = 0, count2 = 0;
+  unsigned int i = 0, j = 0;
+
+  if (pbits < 48)
+    return GPG_ERR_INV_ARG;
+
+  /* We won't use a too strong random elvel for the pooled subprimes. */
+  poolrandomlevel = (randomlevel > GCRY_STRONG_RANDOM?
+                     GCRY_STRONG_RANDOM : randomlevel);
+
+
+  /* If QBITS is not given, assume a reasonable value. */
+  if (!qbits)
+    qbits = pbits / 3;
+
+  req_qbits = qbits;
+
+  /* Find number of needed prime factors N.  */
+  for (n = 1; (pbits - qbits - 1) / n  >= qbits; n++)
+    ;
+  n--;
+
+  val_2 = mpi_alloc_set_ui (2);
+
+  if ((! n) || ((need_q_factor) && (n < 2)))
+    {
+      err = GPG_ERR_INV_ARG;
+      goto leave;
+    }
+
+  if (need_q_factor)
+    {
+      n--;  /* Need one factor less because we want a specific Q-FACTOR. */
+      fbits = (pbits - 2 * req_qbits -1) / n;
+      qbits =  pbits - req_qbits - n * fbits;
+    }
+  else
+    {
+      fbits = (pbits - req_qbits -1) / n;
+      qbits = pbits - n * fbits;
+    }
+  
+  if (DBG_CIPHER)
+    log_debug ("gen prime: pbits=%u qbits=%u fbits=%u/%u n=%d\n",
+               pbits, req_qbits, qbits, fbits, n);
+
+  /* Allocate an integer to old the new prime. */
+  prime = gcry_mpi_new (pbits);
+
+  /* Generate first prime factor.  */
+  q = gen_prime (qbits, is_secret, randomlevel, NULL, NULL);
+
+  /* Generate a specific Q-Factor if requested. */
+  if (need_q_factor)
+    q_factor = gen_prime (req_qbits, is_secret, randomlevel, NULL, NULL);
+  
+  /* Allocate an array to hold all factors + 2 for later usage.  */
+  factors = gcry_calloc (n + 2, sizeof (*factors));
+  if (!factors)
+    {
+      err = gpg_err_code_from_errno (errno);
+      goto leave;
+    }
+
+  /* Allocate an array to track pool usage. */
+  pool_in_use = gcry_malloc (n * sizeof *pool_in_use);
+  if (!pool_in_use)
+    {
+      err = gpg_err_code_from_errno (errno);
+      goto leave;
+    }
+  for (i=0; i < n; i++)
+    pool_in_use[i] = -1;
+      
+  /* Make a pool of 3n+5 primes (this is an arbitrary value).  We
+     require at least 30 primes for are useful selection process. 
+     
+     Fixme: We need to research the best formula for sizing the pool.
+  */
+  m = n * 3 + 5;
+  if (need_q_factor) /* Need some more in this case. */
+    m += 5;
+  if (m < 30)
+    m = 30;
+  pool = gcry_calloc (m , sizeof (*pool));
+  if (! pool)
+    {
+      err = gpg_err_code_from_errno (errno);
+      goto leave;
+    }
+
+  /* Permutate over the pool of primes until we find a prime of the
+     requested length.  */
+  do
+    {
+    next_try:
+      for (i=0; i < n; i++)
+        pool_in_use[i] = -1;
+
+      if (!perms)
+        {
+          /* Allocate new primes.  This is done right at the beginning
+             of the loop and if we have later run out of primes. */
+          for (i = 0; i < m; i++)
+            {
+              mpi_free (pool[i]);
+              pool[i] = NULL;
+            }
+
+          /* Init m_out_of_n().  */
+          perms = gcry_calloc (1, m);
+          if (!perms)
+            {
+              err = gpg_err_code_from_errno (errno);
+              goto leave;
+            }
+
+          if (ath_mutex_lock (&primepool_lock))
+            {
+              err = GPG_ERR_INTERNAL;
+              goto leave;
+            }
+          is_locked = 1;
+          for (i = 0; i < n; i++)
+            {
+              perms[i] = 1; 
+              /* At a maximum we use strong random for the factors.
+                 This saves us a lot of entropy. Given that Q and
+                 possible Q-factor are also used in the final prime
+                 this should be acceptable.  We also don't allocate in
+                 secure memory to save on that scare resource too.  If
+                 Q has been allocated in secure memory, the final
+                 prime will be saved there anyway.  This is because
+                 our MPI routines take care of that.  GnuPG has worked
+                 this way ever since.  */
+              pool[i] = NULL;
+              if (is_locked)
+                {
+                  pool[i] = get_pool_prime (fbits, poolrandomlevel);
+                  if (!pool[i])
+                    {
+                      if (ath_mutex_unlock (&primepool_lock))
+                        {
+                          err = GPG_ERR_INTERNAL;
+                          goto leave;
+                        }
+                      is_locked = 0;
+                    }
+                }
+              if (!pool[i])
+                pool[i] = gen_prime (fbits, 0, poolrandomlevel, NULL, NULL);
+              pool_in_use[i] = i;
+              factors[i] = pool[i];
+            }
+          if (is_locked && ath_mutex_unlock (&primepool_lock))
+            {
+              err = GPG_ERR_INTERNAL;
+              goto leave;
+            }
+          is_locked = 0;
+        }
+      else
+        {
+          /* Get next permutation. */
+          m_out_of_n ( (char*)perms, n, m);
+          if (ath_mutex_lock (&primepool_lock))
+            {
+              err = GPG_ERR_INTERNAL;
+              goto leave;
+            }
+          is_locked = 1;
+          for (i = j = 0; (i < m) && (j < n); i++)
+            if (perms[i])
+              {
+                /* If the subprime has not yet beed generated do it now. */
+                if (!pool[i] && is_locked)
+                  {
+                    pool[i] = get_pool_prime (fbits, poolrandomlevel);
+                    if (!pool[i])
+                      {
+                        if (ath_mutex_unlock (&primepool_lock))
+                          {
+                            err = GPG_ERR_INTERNAL;
+                            goto leave;
+                          }
+                        is_locked = 0;
+                      }
+                  }
+                if (!pool[i])
+                  pool[i] = gen_prime (fbits, 0, poolrandomlevel, NULL, NULL);
+                pool_in_use[j] = i;
+                factors[j++] = pool[i];
+              }
+          if (is_locked && ath_mutex_unlock (&primepool_lock))
+            {
+              err = GPG_ERR_INTERNAL;
+              goto leave;
+            }
+          is_locked = 0;
+          if (i == n)
+            {
+              /* Ran out of permutations: Allocate new primes.  */
+              gcry_free (perms);
+              perms = NULL;
+              progress ('!');
+              goto next_try;	
+            }
+        }
+
+	/* Generate next prime candidate:
+	   p = 2 * q [ * q_factor] * factor_0 * factor_1 * ... * factor_n + 1. 
+         */
+	mpi_set (prime, q);
+	mpi_mul_ui (prime, prime, 2);
+	if (need_q_factor)
+	  mpi_mul (prime, prime, q_factor);
+	for(i = 0; i < n; i++)
+	  mpi_mul (prime, prime, factors[i]);
+	mpi_add_ui (prime, prime, 1);
+	nprime = mpi_get_nbits (prime);
+
+	if (nprime < pbits)
+	  {
+	    if (++count1 > 20)
+	      {
+		count1 = 0;
+		qbits++;
+		progress('>');
+		mpi_free (q);
+		q = gen_prime (qbits, is_secret, randomlevel, NULL, NULL);
+		goto next_try;
+	      }
+	  }
+	else
+	  count1 = 0;
+        
+	if (nprime > pbits)
+	  {
+	    if (++count2 > 20)
+	      {
+		count2 = 0;
+		qbits--;
+		progress('<');
+		mpi_free (q);
+		q = gen_prime (qbits, is_secret, randomlevel, NULL, NULL);
+		goto next_try;
+	      }
+	  }
+	else
+	  count2 = 0;
+    }
+  while (! ((nprime == pbits) && check_prime (prime, val_2, 5,
+                                              cb_func, cb_arg)));
+
+  if (DBG_CIPHER)
+    {
+      progress ('\n');
+      log_mpidump ("prime    : ", prime);
+      log_mpidump ("factor  q: ", q);
+      if (need_q_factor)
+        log_mpidump ("factor q0: ", q_factor);
+      for (i = 0; i < n; i++)
+        log_mpidump ("factor pi: ", factors[i]);
+      log_debug ("bit sizes: prime=%u, q=%u",
+                 mpi_get_nbits (prime), mpi_get_nbits (q));
+      if (need_q_factor)
+        log_debug (", q0=%u", mpi_get_nbits (q_factor));
+      for (i = 0; i < n; i++)
+        log_debug (", p%d=%u", i, mpi_get_nbits (factors[i]));
+      progress('\n');
+    }
+
+  if (ret_factors)
+    {
+      /* Caller wants the factors.  */
+      factors_new = gcry_calloc (n + 4, sizeof (*factors_new));
+      if (! factors_new)
+        {
+          err = gpg_err_code_from_errno (errno);
+          goto leave;
+        }
+
+      if (all_factors)
+        {
+          i = 0;
+          factors_new[i++] = gcry_mpi_set_ui (NULL, 2);
+          factors_new[i++] = mpi_copy (q);
+          if (need_q_factor)
+            factors_new[i++] = mpi_copy (q_factor);
+          for(j=0; j < n; j++)
+            factors_new[i++] = mpi_copy (factors[j]);
+        }
+      else
+        {
+          i = 0;
+          if (need_q_factor)
+            {
+              factors_new[i++] = mpi_copy (q_factor);
+              for (; i <= n; i++)
+                factors_new[i] = mpi_copy (factors[i]);
+            }
+          else
+            for (; i < n; i++ )
+              factors_new[i] = mpi_copy (factors[i]);
+        }
+    }
+  
+  if (g)
+    {
+      /* Create a generator (start with 3).  */
+      gcry_mpi_t tmp = mpi_alloc (mpi_get_nlimbs (prime));
+      gcry_mpi_t b = mpi_alloc (mpi_get_nlimbs (prime));
+      gcry_mpi_t pmin1 = mpi_alloc (mpi_get_nlimbs (prime));
+      
+      if (need_q_factor)
+        err = GPG_ERR_NOT_IMPLEMENTED;
+      else
+        {
+          factors[n] = q;
+          factors[n + 1] = mpi_alloc_set_ui (2);
+          mpi_sub_ui (pmin1, prime, 1);
+          mpi_set_ui (g, 2);
+          do
+            {
+              mpi_add_ui (g, g, 1);
+              if (DBG_CIPHER)
+                {
+                  log_debug ("checking g:");
+                  gcry_mpi_dump (g);
+                  log_printf ("\n");
+                }
+              else
+                progress('^');
+              for (i = 0; i < n + 2; i++)
+                {
+                  mpi_fdiv_q (tmp, pmin1, factors[i]);
+                  /* No mpi_pow(), but it is okay to use this with mod
+                     prime.  */
+                  gcry_mpi_powm (b, g, tmp, prime);
+                  if (! mpi_cmp_ui (b, 1))
+                    break;
+                }
+              if (DBG_CIPHER)
+                progress('\n');
+            } 
+          while (i < n + 2);
+
+          mpi_free (factors[n+1]);
+          mpi_free (tmp);
+          mpi_free (b);
+          mpi_free (pmin1);
+        }
+    }
+  
+  if (! DBG_CIPHER)
+    progress ('\n');
+
+
+ leave:
+  if (pool)
+    {
+      is_locked = !ath_mutex_lock (&primepool_lock);
+      for(i = 0; i < m; i++)
+        {
+          if (pool[i])
+            {
+              for (j=0; j < n; j++)
+                if (pool_in_use[j] == i)
+                  break;
+              if (j == n && is_locked)
+                {
+                  /* This pooled subprime has not been used. */
+                  save_pool_prime (pool[i], poolrandomlevel);
+                }
+              else
+                mpi_free (pool[i]);
+            }
+        }
+      if (is_locked && ath_mutex_unlock (&primepool_lock))
+        err = GPG_ERR_INTERNAL;
+      is_locked = 0;
+      gcry_free (pool);
+    }
+  gcry_free (pool_in_use);
+  if (factors)
+    gcry_free (factors);  /* Factors are shallow copies.  */
+  if (perms)
+    gcry_free (perms);
+
+  mpi_free (val_2);
+  mpi_free (q);
+  mpi_free (q_factor);
+
+  if (! err)
+    {
+      *prime_generated = prime;
+      if (ret_factors)
+	*ret_factors = factors_new;
+    }
+  else
+    {
+      if (factors_new)
+	{
+	  for (i = 0; factors_new[i]; i++)
+	    mpi_free (factors_new[i]);
+	  gcry_free (factors_new);
+	}
+      mpi_free (prime);
+    }
+
+  return err;
+}
+
+
+/* Generate a prime used for discrete logarithm algorithms; i.e. this
+   prime will be public and no strong random is required.  */
+gcry_mpi_t
+_gcry_generate_elg_prime (int mode, unsigned pbits, unsigned qbits,
+			  gcry_mpi_t g, gcry_mpi_t **ret_factors)
+{
+  gcry_err_code_t err = GPG_ERR_NO_ERROR;
+  gcry_mpi_t prime = NULL;
+  
+  err = prime_generate_internal ((mode == 1), &prime, pbits, qbits, g,
+				 ret_factors, GCRY_WEAK_RANDOM, 0, 0,
+                                 NULL, NULL);
+
+  return prime;
+}
+
+
+static gcry_mpi_t
+gen_prime (unsigned int nbits, int secret, int randomlevel, 
+           int (*extra_check)(void *, gcry_mpi_t), void *extra_check_arg)
+{
+  gcry_mpi_t prime, ptest, pminus1, val_2, val_3, result;
+  int i;
+  unsigned int x, step;
+  unsigned int count1, count2;
+  int *mods;
+  
+/*   if (  DBG_CIPHER ) */
+/*     log_debug ("generate a prime of %u bits ", nbits ); */
+
+  if (nbits < 16)
+    log_fatal ("can't generate a prime with less than %d bits\n", 16);
+
+  mods = gcry_xmalloc( no_of_small_prime_numbers * sizeof *mods );
+  /* Make nbits fit into gcry_mpi_t implementation. */
+  val_2  = mpi_alloc_set_ui( 2 );
+  val_3 = mpi_alloc_set_ui( 3);
+  prime  = secret? gcry_mpi_snew ( nbits ): gcry_mpi_new ( nbits );
+  result = mpi_alloc_like( prime );
+  pminus1= mpi_alloc_like( prime );
+  ptest  = mpi_alloc_like( prime );
+  count1 = count2 = 0;
+  for (;;)
+    {  /* try forvever */
+      int dotcount=0;
+      
+      /* generate a random number */
+      gcry_mpi_randomize( prime, nbits, randomlevel );
+      
+      /* Set high order bit to 1, set low order bit to 1.  If we are
+         generating a secret prime we are most probably doing that
+         for RSA, to make sure that the modulus does have the
+         requested key size we set the 2 high order bits. */
+      mpi_set_highbit (prime, nbits-1);
+      if (secret)
+        mpi_set_bit (prime, nbits-2);
+      mpi_set_bit(prime, 0);
+      
+      /* Calculate all remainders. */
+      for (i=0; (x = small_prime_numbers[i]); i++ )
+        mods[i] = mpi_fdiv_r_ui(NULL, prime, x);
+      
+      /* Now try some primes starting with prime. */
+      for(step=0; step < 20000; step += 2 ) 
+        {
+          /* Check against all the small primes we have in mods. */
+          count1++;
+          for (i=0; (x = small_prime_numbers[i]); i++ ) 
+            {
+              while ( mods[i] + step >= x )
+                mods[i] -= x;
+              if ( !(mods[i] + step) )
+                break;
+	    }
+          if ( x )
+            continue;   /* Found a multiple of an already known prime. */
+          
+          mpi_add_ui( ptest, prime, step );
+
+          /* Do a fast Fermat test now. */
+          count2++;
+          mpi_sub_ui( pminus1, ptest, 1);
+          gcry_mpi_powm( result, val_2, pminus1, ptest );
+          if ( !mpi_cmp_ui( result, 1 ) )
+            { 
+              /* Not composite, perform stronger tests */
+              if (is_prime(ptest, 5, &count2 ))
+                {
+                  if (!mpi_test_bit( ptest, nbits-1-secret ))
+                    {
+                      progress('\n');
+                      log_debug ("overflow in prime generation\n");
+                      break; /* Stop loop, continue with a new prime. */
+                    }
+
+                  if (extra_check && extra_check (extra_check_arg, ptest))
+                    { 
+                      /* The extra check told us that this prime is
+                         not of the caller's taste. */
+                      progress ('/');
+                    }
+                  else
+                    { 
+                      /* Got it. */
+                      mpi_free(val_2);
+                      mpi_free(val_3);
+                      mpi_free(result);
+                      mpi_free(pminus1);
+                      mpi_free(prime);
+                      gcry_free(mods);
+                      return ptest; 
+                    }
+                }
+	    }
+          if (++dotcount == 10 )
+            {
+              progress('.');
+              dotcount = 0;
+	    }
+	}
+      progress(':'); /* restart with a new random value */
+    }
+}
+
+/****************
+ * Returns: true if this may be a prime
+ * RM_ROUNDS gives the number of Rabin-Miller tests to run.
+ */
+static int
+check_prime( gcry_mpi_t prime, gcry_mpi_t val_2, int rm_rounds,
+             gcry_prime_check_func_t cb_func, void *cb_arg)
+{
+  int i;
+  unsigned int x;
+  unsigned int count=0;
+
+  /* Check against small primes. */
+  for (i=0; (x = small_prime_numbers[i]); i++ )
+    {
+      if ( mpi_divisible_ui( prime, x ) )
+        return 0;
+    }
+
+  /* A quick Fermat test. */
+  {
+    gcry_mpi_t result = mpi_alloc_like( prime );
+    gcry_mpi_t pminus1 = mpi_alloc_like( prime );
+    mpi_sub_ui( pminus1, prime, 1);
+    gcry_mpi_powm( result, val_2, pminus1, prime );
+    mpi_free( pminus1 );
+    if ( mpi_cmp_ui( result, 1 ) )
+      { 
+        /* Is composite. */
+        mpi_free( result );
+        progress('.');
+        return 0;
+      }
+    mpi_free( result );
+  }
+
+  if (!cb_func || cb_func (cb_arg, GCRY_PRIME_CHECK_AT_MAYBE_PRIME, prime))
+    {
+      /* Perform stronger tests. */
+      if ( is_prime( prime, rm_rounds, &count ) )
+        {
+          if (!cb_func
+              || cb_func (cb_arg, GCRY_PRIME_CHECK_AT_GOT_PRIME, prime))
+            return 1; /* Probably a prime. */
+        }
+    }
+  progress('.');
+  return 0;
+}
+
+
+/*
+ * Return true if n is probably a prime
+ */
+static int
+is_prime (gcry_mpi_t n, int steps, unsigned int *count)
+{
+  gcry_mpi_t x = mpi_alloc( mpi_get_nlimbs( n ) );
+  gcry_mpi_t y = mpi_alloc( mpi_get_nlimbs( n ) );
+  gcry_mpi_t z = mpi_alloc( mpi_get_nlimbs( n ) );
+  gcry_mpi_t nminus1 = mpi_alloc( mpi_get_nlimbs( n ) );
+  gcry_mpi_t a2 = mpi_alloc_set_ui( 2 );
+  gcry_mpi_t q;
+  unsigned i, j, k;
+  int rc = 0;
+  unsigned nbits = mpi_get_nbits( n );
+
+  if (steps < 5) /* Make sure that we do at least 5 rounds. */
+    steps = 5; 
+
+  mpi_sub_ui( nminus1, n, 1 );
+
+  /* Find q and k, so that n = 1 + 2^k * q . */
+  q = mpi_copy ( nminus1 );
+  k = mpi_trailing_zeros ( q );
+  mpi_tdiv_q_2exp (q, q, k);
+
+  for (i=0 ; i < steps; i++ )
+    {
+      ++*count;
+      if( !i )
+        {
+          mpi_set_ui( x, 2 );
+        }
+      else
+        {
+          gcry_mpi_randomize( x, nbits, GCRY_WEAK_RANDOM );
+
+          /* Make sure that the number is smaller than the prime and
+             keep the randomness of the high bit. */
+          if ( mpi_test_bit ( x, nbits-2) )
+            {
+              mpi_set_highbit ( x, nbits-2); /* Clear all higher bits. */
+            }
+          else
+            {
+              mpi_set_highbit( x, nbits-2 );
+              mpi_clear_bit( x, nbits-2 );
+            }
+          gcry_assert (mpi_cmp (x, nminus1) < 0 && mpi_cmp_ui (x, 1) > 0);
+	}
+      gcry_mpi_powm ( y, x, q, n);
+      if ( mpi_cmp_ui(y, 1) && mpi_cmp( y, nminus1 ) )
+        {
+          for ( j=1; j < k && mpi_cmp( y, nminus1 ); j++ )
+            {
+              gcry_mpi_powm(y, y, a2, n);
+              if( !mpi_cmp_ui( y, 1 ) )
+                goto leave; /* Not a prime. */
+            }
+          if (mpi_cmp( y, nminus1 ) )
+            goto leave; /* Not a prime. */
+	}
+      progress('+');
+    }
+  rc = 1; /* May be a prime. */
+
+ leave:
+  mpi_free( x );
+  mpi_free( y );
+  mpi_free( z );
+  mpi_free( nminus1 );
+  mpi_free( q );
+  mpi_free( a2 );
+
+  return rc;
+}
+
+
+/* Given ARRAY of size N with M elements set to true produce a
+   modified array with the next permutation of M elements.  Note, that
+   ARRAY is used in a one-bit-per-byte approach.  To detected the last
+   permutation it is useful to intialize the array with the first M
+   element set to true and use this test:
+       m_out_of_n (array, m, n);
+       for (i = j = 0; i < n && j < m; i++)
+         if (array[i])
+           j++;
+       if (j == m)
+         goto ready;
+     
+   This code is based on the algorithm 452 from the "Collected
+   Algorithms From ACM, Volume II" by C. N. Liu and D. T. Tang.
+*/
+static void
+m_out_of_n ( char *array, int m, int n )
+{
+  int i=0, i1=0, j=0, jp=0,  j1=0, k1=0, k2=0;
+
+  if( !m || m >= n )
+    return;
+
+  /* Need to handle this simple case separately. */
+  if( m == 1 )
+    { 
+      for (i=0; i < n; i++ )
+        {
+          if ( array[i] )
+            {
+              array[i++] = 0;
+              if( i >= n )
+                i = 0;
+              array[i] = 1;
+              return;
+            }
+        }
+      BUG();
+    }
+
+
+  for (j=1; j < n; j++ )
+    {
+      if ( array[n-1] == array[n-j-1])
+        continue;
+      j1 = j;
+      break;
+    }
+
+  if ( (m & 1) )
+    {
+      /* M is odd. */
+      if( array[n-1] )
+        {
+          if( j1 & 1 )
+            {
+              k1 = n - j1;
+              k2 = k1+2;
+              if( k2 > n )
+                k2 = n;
+              goto leave;
+            }
+          goto scan;
+        }
+      k2 = n - j1 - 1;
+      if( k2 == 0 )
+        {
+          k1 = i;
+          k2 = n - j1;
+        }
+      else if( array[k2] && array[k2-1] )
+        k1 = n;
+      else
+        k1 = k2 + 1;
+    }
+  else 
+    {
+      /* M is even. */
+      if( !array[n-1] )
+        {
+          k1 = n - j1;
+          k2 = k1 + 1;
+          goto leave;
+        }
+        
+      if( !(j1 & 1) )
+        {
+          k1 = n - j1;
+          k2 = k1+2;
+          if( k2 > n )
+            k2 = n;
+          goto leave;
+        }
+    scan:
+      jp = n - j1 - 1;
+      for (i=1; i <= jp; i++ ) 
+        {
+          i1 = jp + 2 - i;
+          if( array[i1-1]  )
+            {
+              if( array[i1-2] )
+                {
+                  k1 = i1 - 1;
+                  k2 = n - j1;
+		}
+              else
+                {
+                  k1 = i1 - 1;
+                  k2 = n + 1 - j1;
+                }
+              goto leave;
+            }
+        }
+      k1 = 1;
+      k2 = n + 1 - m;
+    }
+ leave:
+  /* Now complement the two selected bits. */
+  array[k1-1] = !array[k1-1];
+  array[k2-1] = !array[k2-1];
+}
+
+
+/* Generate a new prime number of PRIME_BITS bits and store it in
+   PRIME.  If FACTOR_BITS is non-zero, one of the prime factors of
+   (prime - 1) / 2 must be FACTOR_BITS bits long.  If FACTORS is
+   non-zero, allocate a new, NULL-terminated array holding the prime
+   factors and store it in FACTORS.  FLAGS might be used to influence
+   the prime number generation process.  */
+gcry_error_t
+gcry_prime_generate (gcry_mpi_t *prime, unsigned int prime_bits,
+		     unsigned int factor_bits, gcry_mpi_t **factors,
+		     gcry_prime_check_func_t cb_func, void *cb_arg,
+		     gcry_random_level_t random_level,
+		     unsigned int flags)
+{
+  gcry_err_code_t err = GPG_ERR_NO_ERROR;
+  gcry_mpi_t *factors_generated = NULL;
+  gcry_mpi_t prime_generated = NULL;
+  unsigned int mode = 0;
+
+  if (!prime)
+    return gpg_error (GPG_ERR_INV_ARG);
+  *prime = NULL; 
+
+  if (flags & GCRY_PRIME_FLAG_SPECIAL_FACTOR)
+    mode = 1;
+
+  /* Generate.  */
+  err = prime_generate_internal ((mode==1), &prime_generated, prime_bits,
+				 factor_bits, NULL,
+                                 factors? &factors_generated : NULL,
+				 random_level, flags, 1,
+                                 cb_func, cb_arg);
+
+  if (! err)
+    if (cb_func)
+      {
+	/* Additional check. */
+	if ( !cb_func (cb_arg, GCRY_PRIME_CHECK_AT_FINISH, prime_generated))
+	  {
+	    /* Failed, deallocate resources.  */
+	    unsigned int i;
+
+	    mpi_free (prime_generated);
+            if (factors)
+              {
+                for (i = 0; factors_generated[i]; i++)
+                  mpi_free (factors_generated[i]);
+                gcry_free (factors_generated);
+              }
+	    err = GPG_ERR_GENERAL; 
+	  }
+      }
+
+  if (! err)
+    {
+      if (factors)
+        *factors = factors_generated;
+      *prime = prime_generated;
+    }
+
+  return gcry_error (err);
+}
+
+/* Check wether the number X is prime.  */
+gcry_error_t
+gcry_prime_check (gcry_mpi_t x, unsigned int flags)
+{
+  gcry_err_code_t err = GPG_ERR_NO_ERROR;
+  gcry_mpi_t val_2 = mpi_alloc_set_ui (2); /* Used by the Fermat test. */
+
+  (void)flags;
+
+  /* We use 64 rounds because the prime we are going to test is not
+     guaranteed to be a random one. */
+  if (! check_prime (x, val_2, 64, NULL, NULL))
+    err = GPG_ERR_NO_PRIME;
+
+  mpi_free (val_2);
+
+  return gcry_error (err);
+}
+
+/* Find a generator for PRIME where the factorization of (prime-1) is
+   in the NULL terminated array FACTORS. Return the generator as a
+   newly allocated MPI in R_G.  If START_G is not NULL, use this as s
+   atart for the search. Returns 0 on success.*/
+gcry_error_t
+gcry_prime_group_generator (gcry_mpi_t *r_g,
+                            gcry_mpi_t prime, gcry_mpi_t *factors,
+                            gcry_mpi_t start_g)
+{
+  gcry_mpi_t tmp = gcry_mpi_new (0);
+  gcry_mpi_t b = gcry_mpi_new (0);
+  gcry_mpi_t pmin1 = gcry_mpi_new (0);
+  gcry_mpi_t g = start_g? gcry_mpi_copy (start_g) : gcry_mpi_set_ui (NULL, 3);
+  int first = 1;
+  int i, n;
+
+  if (!factors || !r_g || !prime)
+    return gpg_error (GPG_ERR_INV_ARG);
+  *r_g = NULL; 
+
+  for (n=0; factors[n]; n++)
+    ;
+  if (n < 2)
+    return gpg_error (GPG_ERR_INV_ARG);
+
+  /* Extra sanity check - usually disabled. */  
+/*   mpi_set (tmp, factors[0]); */
+/*   for(i = 1; i < n; i++) */
+/*     mpi_mul (tmp, tmp, factors[i]); */
+/*   mpi_add_ui (tmp, tmp, 1); */
+/*   if (mpi_cmp (prime, tmp)) */
+/*     return gpg_error (GPG_ERR_INV_ARG); */
+  
+  gcry_mpi_sub_ui (pmin1, prime, 1);      
+  do         
+    {
+      if (first)
+        first = 0;
+      else
+        gcry_mpi_add_ui (g, g, 1);
+      
+      if (DBG_CIPHER)
+        {
+          log_debug ("checking g:");
+          gcry_mpi_dump (g);
+          log_debug ("\n");
+        }
+      else
+        progress('^');
+      
+      for (i = 0; i < n; i++)
+        {
+          mpi_fdiv_q (tmp, pmin1, factors[i]);
+          gcry_mpi_powm (b, g, tmp, prime);
+          if (! mpi_cmp_ui (b, 1))
+            break;
+        }
+      if (DBG_CIPHER)
+        progress('\n');
+    }
+  while (i < n);
+  
+  gcry_mpi_release (tmp);
+  gcry_mpi_release (b); 
+  gcry_mpi_release (pmin1); 
+  *r_g = g; 
+
+  return 0; 
+}
+
+/* Convenience function to release the factors array. */
+void
+gcry_prime_release_factors (gcry_mpi_t *factors)
+{
+  if (factors)
+    {
+      int i;
+      
+      for (i=0; factors[i]; i++)
+        mpi_free (factors[i]);
+      gcry_free (factors);
+    }
+}
+
+
+
+/* Helper for _gcry_derive_x931_prime.  */
+static gcry_mpi_t
+find_x931_prime (const gcry_mpi_t pfirst)
+{
+  gcry_mpi_t val_2 = mpi_alloc_set_ui (2); 
+  gcry_mpi_t prime;
+  
+  prime = gcry_mpi_copy (pfirst);
+  /* If P is even add 1.  */ 
+  mpi_set_bit (prime, 0);
+
+  /* We use 64 Rabin-Miller rounds which is better and thus
+     sufficient.  We do not have a Lucas test implementaion thus we
+     can't do it in the X9.31 preferred way of running a few
+     Rabin-Miller followed by one Lucas test.  */
+  while ( !check_prime (prime, val_2, 64, NULL, NULL) )
+    mpi_add_ui (prime, prime, 2);
+
+  mpi_free (val_2);
+
+  return prime;
+}
+
+
+/* Generate a prime using the algorithm from X9.31 appendix B.4. 
+
+   This function requires that the provided public exponent E is odd.
+   XP, XP1 and XP2 are the seed values.  All values are mandatory.
+
+   On success the prime is returned.  If R_P1 or R_P2 are given the
+   internal values P1 and P2 are saved at these addresses.  On error
+   NULL is returned.  */
+gcry_mpi_t
+_gcry_derive_x931_prime (const gcry_mpi_t xp, 
+                         const gcry_mpi_t xp1, const gcry_mpi_t xp2,
+                         const gcry_mpi_t e,
+                         gcry_mpi_t *r_p1, gcry_mpi_t *r_p2)
+{
+  gcry_mpi_t p1, p2, p1p2, yp0;
+
+  if (!xp || !xp1 || !xp2)
+    return NULL;
+  if (!e || !mpi_test_bit (e, 0))
+    return NULL;  /* We support only odd values for E.  */
+
+  p1 = find_x931_prime (xp1);
+  p2 = find_x931_prime (xp2);
+  p1p2 = mpi_alloc_like (xp);
+  mpi_mul (p1p2, p1, p2);
+
+  {
+    gcry_mpi_t r1, tmp;
+  
+    /* r1 = (p2^{-1} mod p1)p2 - (p1^{-1} mod p2) */
+    tmp = mpi_alloc_like (p1);
+    mpi_invm (tmp, p2, p1);
+    mpi_mul (tmp, tmp, p2);
+    r1 = tmp;
+    
+    tmp = mpi_alloc_like (p2);
+    mpi_invm (tmp, p1, p2);
+    mpi_mul (tmp, tmp, p1);
+    mpi_sub (r1, r1, tmp);
+
+    /* Fixup a negative value.  */
+    if (mpi_is_neg (r1)) 
+      mpi_add (r1, r1, p1p2);
+
+    /* yp0 = xp + (r1 - xp mod p1*p2)  */
+    yp0 = tmp; tmp = NULL;
+    mpi_subm (yp0, r1, xp, p1p2);
+    mpi_add (yp0, yp0, xp);
+    mpi_free (r1);
+
+    /* Fixup a negative value.  */
+    if (mpi_cmp (yp0, xp) < 0 ) 
+      mpi_add (yp0, yp0, p1p2);
+  }
+
+  /* yp0 is now the first integer greater than xp with p1 being a
+     large prime factor of yp0-1 and p2 a large prime factor of yp0+1.  */
+
+  /* Note that the first example from X9.31 (D.1.1) which uses
+       (Xq1 #1A5CF72EE770DE50CB09ACCEA9#)
+       (Xq2 #134E4CAA16D2350A21D775C404#)
+       (Xq  #CC1092495D867E64065DEE3E7955F2EBC7D47A2D
+             7C9953388F97DDDC3E1CA19C35CA659EDC2FC325
+             6D29C2627479C086A699A49C4C9CEE7EF7BD1B34
+             321DE34A#))))
+     returns an yp0 of
+            #CC1092495D867E64065DEE3E7955F2EBC7D47A2D
+             7C9953388F97DDDC3E1CA19C35CA659EDC2FC4E3
+             BF20CB896EE37E098A906313271422162CB6C642
+             75C1201F#
+     and not
+            #CC1092495D867E64065DEE3E7955F2EBC7D47A2D
+             7C9953388F97DDDC3E1CA19C35CA659EDC2FC2E6
+             C88FE299D52D78BE405A97E01FD71DD7819ECB91
+             FA85A076#
+     as stated in the standard.  This seems to be a bug in X9.31.
+   */
+
+  {
+    gcry_mpi_t val_2 = mpi_alloc_set_ui (2); 
+    gcry_mpi_t gcdtmp = mpi_alloc_like (yp0);
+    int gcdres;
+  
+    mpi_sub_ui (p1p2, p1p2, 1); /* Adjust for loop body.  */
+    mpi_sub_ui (yp0, yp0, 1);   /* Ditto.  */
+    for (;;)
+      {
+        gcdres = gcry_mpi_gcd (gcdtmp, e, yp0);
+        mpi_add_ui (yp0, yp0, 1);
+        if (!gcdres)
+          progress ('/');  /* gcd (e, yp0-1) != 1  */
+        else if (check_prime (yp0, val_2, 64, NULL, NULL))
+          break; /* Found.  */
+        /* We add p1p2-1 because yp0 is incremented after the gcd test.  */
+        mpi_add (yp0, yp0, p1p2);
+      }
+    mpi_free (gcdtmp);
+    mpi_free (val_2);
+  }
+
+  mpi_free (p1p2);
+
+  progress('\n');
+  if (r_p1)
+    *r_p1 = p1;
+  else
+    mpi_free (p1);
+  if (r_p2)
+    *r_p2 = p2;
+  else
+    mpi_free (p2);
+  return yp0;
+}
+
+
+
+/* Generate the two prime used for DSA using the algorithm specified
+   in FIPS 186-2.  PBITS is the desired length of the prime P and a
+   QBITS the length of the prime Q.  If SEED is not supplied and
+   SEEDLEN is 0 the function generates an appropriate SEED.  On
+   success the generated primes are stored at R_Q and R_P, the counter
+   value is stored at R_COUNTER and the seed actually used for
+   generation is stored at R_SEED and R_SEEDVALUE.  */
+gpg_err_code_t
+_gcry_generate_fips186_2_prime (unsigned int pbits, unsigned int qbits,
+                                const void *seed, size_t seedlen,
+                                gcry_mpi_t *r_q, gcry_mpi_t *r_p,
+                                int *r_counter,
+                                void **r_seed, size_t *r_seedlen)
+{
+  gpg_err_code_t ec;
+  unsigned char seed_help_buffer[160/8];  /* Used to hold a generated SEED. */
+  unsigned char *seed_plus;     /* Malloced buffer to hold SEED+x.  */
+  unsigned char digest[160/8];  /* Helper buffer for SHA-1 digest.  */
+  gcry_mpi_t val_2 = NULL;      /* Helper for the prime test.  */
+  gcry_mpi_t tmpval = NULL;     /* Helper variable.  */
+  int i;
+
+  unsigned char value_u[160/8];
+  int value_n, value_b, value_k;
+  int counter;
+  gcry_mpi_t value_w = NULL;
+  gcry_mpi_t value_x = NULL;
+  gcry_mpi_t prime_q = NULL;
+  gcry_mpi_t prime_p = NULL;
+
+  /* FIPS 186-2 allows only for 1024/160 bit.  */
+  if (pbits != 1024 || qbits != 160)
+    return GPG_ERR_INV_KEYLEN;
+
+  if (!seed && !seedlen)
+    ; /* No seed value given:  We are asked to generate it.  */
+  else if (!seed || seedlen < qbits/8)
+    return GPG_ERR_INV_ARG;
+  
+  /* Allocate a buffer to later compute SEED+some_increment. */
+  seed_plus = gcry_malloc (seedlen < 20? 20:seedlen);
+  if (!seed_plus)
+    {
+      ec = gpg_err_code_from_syserror ();
+      goto leave;
+    }
+
+  val_2   = mpi_alloc_set_ui (2);
+  value_n = (pbits - 1) / qbits;
+  value_b = (pbits - 1) - value_n * qbits;
+  value_w = gcry_mpi_new (pbits);
+  value_x = gcry_mpi_new (pbits);
+
+ restart:  
+  /* Generate Q.  */
+  for (;;)
+    {
+      /* Step 1: Generate a (new) seed unless one has been supplied.  */
+      if (!seed)
+        {
+          seedlen = sizeof seed_help_buffer;
+          gcry_create_nonce (seed_help_buffer, seedlen);
+          seed = seed_help_buffer;
+        }
+      
+      /* Step 2: U = sha1(seed) ^ sha1((seed+1) mod 2^{qbits})  */
+      memcpy (seed_plus, seed, seedlen);
+      for (i=seedlen-1; i >= 0; i--)
+        {
+          seed_plus[i]++;
+          if (seed_plus[i])
+            break;
+        }
+      gcry_md_hash_buffer (GCRY_MD_SHA1, value_u, seed, seedlen);
+      gcry_md_hash_buffer (GCRY_MD_SHA1, digest, seed_plus, seedlen);
+      for (i=0; i < sizeof value_u; i++)
+        value_u[i] ^= digest[i];
+  
+      /* Step 3:  Form q from U  */
+      gcry_mpi_release (prime_q); prime_q = NULL;
+      ec = gpg_err_code (gcry_mpi_scan (&prime_q, GCRYMPI_FMT_USG, 
+                                        value_u, sizeof value_u, NULL));
+      if (ec)
+        goto leave;
+      mpi_set_highbit (prime_q, qbits-1 );
+      mpi_set_bit (prime_q, 0);
+      
+      /* Step 4:  Test whether Q is prime using 64 round of Rabin-Miller.  */
+      if (check_prime (prime_q, val_2, 64, NULL, NULL))
+        break; /* Yes, Q is prime.  */
+
+      /* Step 5.  */
+      seed = NULL;  /* Force a new seed at Step 1.  */
+    }
+  
+  /* Step 6.  Note that we do no use an explicit offset but increment
+     SEED_PLUS accordingly.  SEED_PLUS is currently SEED+1.  */
+  counter = 0;
+
+  /* Generate P. */
+  prime_p = gcry_mpi_new (pbits);
+  for (;;)
+    {
+      /* Step 7: For k = 0,...n let 
+                   V_k = sha1(seed+offset+k) mod 2^{qbits}  
+         Step 8: W = V_0 + V_1*2^160 + 
+                         ... 
+                         + V_{n-1}*2^{(n-1)*160}
+                         + (V_{n} mod 2^b)*2^{n*160}                
+       */
+      mpi_set_ui (value_w, 0);
+      for (value_k=0; value_k <= value_n; value_k++)
+        {
+          /* There is no need to have an explicit offset variable:  In
+             the first round we shall have an offset of 2, this is
+             achieved by using SEED_PLUS which is already at SEED+1,
+             thus we just need to increment it once again.  The
+             requirement for the next round is to update offset by N,
+             which we implictly did at the end of this loop, and then
+             to add one; this one is the same as in the first round.  */
+          for (i=seedlen-1; i >= 0; i--)
+            {
+              seed_plus[i]++;
+              if (seed_plus[i])
+                break;
+            }
+          gcry_md_hash_buffer (GCRY_MD_SHA1, digest, seed_plus, seedlen);
+          
+          gcry_mpi_release (tmpval); tmpval = NULL;
+          ec = gpg_err_code (gcry_mpi_scan (&tmpval, GCRYMPI_FMT_USG,
+                                            digest, sizeof digest, NULL));
+          if (ec)
+            goto leave;
+          if (value_k == value_n)
+            mpi_clear_highbit (tmpval, value_b); /* (V_n mod 2^b) */
+          mpi_lshift (tmpval, tmpval, value_k*qbits);
+          mpi_add (value_w, value_w, tmpval);
+        }
+
+      /* Step 8 continued: X = W + 2^{L-1}  */
+      mpi_set_ui (value_x, 0);
+      mpi_set_highbit (value_x, pbits-1);
+      mpi_add (value_x, value_x, value_w);
+
+      /* Step 9:  c = X mod 2q,  p = X - (c - 1)  */
+      mpi_mul_2exp (tmpval, prime_q, 1);
+      mpi_mod (tmpval, value_x, tmpval);
+      mpi_sub_ui (tmpval, tmpval, 1);
+      mpi_sub (prime_p, value_x, tmpval);
+
+      /* Step 10: If  p < 2^{L-1}  skip the primality test.  */
+      /* Step 11 and 12: Primality test.  */
+      if (mpi_get_nbits (prime_p) >= pbits-1
+          && check_prime (prime_p, val_2, 64, NULL, NULL) )
+        break; /* Yes, P is prime, continue with Step 15.  */
+
+      /* Step 13: counter = counter + 1, offset = offset + n + 1. */
+      counter++;
+
+      /* Step 14: If counter >= 2^12  goto Step 1.  */
+      if (counter >= 4096)
+        goto restart;
+    }
+
+  /* Step 15:  Save p, q, counter and seed.  */
+/*   log_debug ("fips186-2 pbits p=%u q=%u counter=%d\n", */
+/*              mpi_get_nbits (prime_p), mpi_get_nbits (prime_q), counter); */
+/*   log_printhex("fips186-2 seed:", seed, seedlen); */
+/*   log_mpidump ("fips186-2 prime p", prime_p); */
+/*   log_mpidump ("fips186-2 prime q", prime_q); */
+  if (r_q)
+    {
+      *r_q = prime_q;
+      prime_q = NULL;
+    }
+  if (r_p)
+    {
+      *r_p = prime_p;
+      prime_p = NULL;
+    }
+  if (r_counter)
+    *r_counter = counter;
+  if (r_seed && r_seedlen)
+    {
+      memcpy (seed_plus, seed, seedlen);
+      *r_seed = seed_plus;
+      seed_plus = NULL;
+      *r_seedlen = seedlen;
+    }
+
+
+ leave:
+  gcry_mpi_release (tmpval);
+  gcry_mpi_release (value_x);
+  gcry_mpi_release (value_w);
+  gcry_mpi_release (prime_p);
+  gcry_mpi_release (prime_q);
+  gcry_free (seed_plus);
+  gcry_mpi_release (val_2);
+  return ec;
+}
+
+
+
+/* WARNING: The code below has not yet been tested!  However, it is
+   not yet used.  We need to wait for FIPS 186-3 final and for test
+   vectors.
+
+   Generate the two prime used for DSA using the algorithm specified
+   in FIPS 186-3, A.1.1.2.  PBITS is the desired length of the prime P
+   and a QBITS the length of the prime Q.  If SEED is not supplied and
+   SEEDLEN is 0 the function generates an appropriate SEED.  On
+   success the generated primes are stored at R_Q and R_P, the counter
+   value is stored at R_COUNTER and the seed actually used for
+   generation is stored at R_SEED and R_SEEDVALUE.  The hash algorithm
+   used is stored at R_HASHALGO.
+   
+   Note that this function is very similar to the fips186_2 code.  Due
+   to the minor differences, other buffer sizes and for documentarion,
+   we use a separate function.
+*/
+gpg_err_code_t
+_gcry_generate_fips186_3_prime (unsigned int pbits, unsigned int qbits,
+                                const void *seed, size_t seedlen,
+                                gcry_mpi_t *r_q, gcry_mpi_t *r_p,
+                                int *r_counter,
+                                void **r_seed, size_t *r_seedlen,
+                                int *r_hashalgo)
+{
+  gpg_err_code_t ec;
+  unsigned char seed_help_buffer[256/8];  /* Used to hold a generated SEED. */
+  unsigned char *seed_plus;     /* Malloced buffer to hold SEED+x.  */
+  unsigned char digest[256/8];  /* Helper buffer for SHA-1 digest.  */
+  gcry_mpi_t val_2 = NULL;      /* Helper for the prime test.  */
+  gcry_mpi_t tmpval = NULL;     /* Helper variable.  */
+  int hashalgo;                 /* The id of the Approved Hash Function.  */
+  int i;
+  
+  unsigned char value_u[256/8];
+  int value_n, value_b, value_j;
+  int counter;
+  gcry_mpi_t value_w = NULL;
+  gcry_mpi_t value_x = NULL;
+  gcry_mpi_t prime_q = NULL;
+  gcry_mpi_t prime_p = NULL;
+
+  gcry_assert (sizeof seed_help_buffer == sizeof digest
+               && sizeof seed_help_buffer == sizeof value_u);
+
+  /* Step 1:  Check the requested prime lengths.  */
+  /* Note that due to the size of our buffers QBITS is limited to 256.  */
+  if (pbits == 1024 && qbits == 160)
+    hashalgo = GCRY_MD_SHA1;
+  else if (pbits == 2048 && qbits == 224)
+    hashalgo = GCRY_MD_SHA224;
+  else if (pbits == 2048 && qbits == 256)
+    hashalgo = GCRY_MD_SHA256;
+  else if (pbits == 3072 && qbits == 256)
+    hashalgo = GCRY_MD_SHA256;
+  else
+    return GPG_ERR_INV_KEYLEN;
+
+  /* Also check that the hash algorithm is available.  */
+  ec = gpg_err_code (gcry_md_test_algo (hashalgo));
+  if (ec)
+    return ec;
+  gcry_assert (qbits/8 <= sizeof digest);
+  gcry_assert (gcry_md_get_algo_dlen (hashalgo) == qbits/8);
+
+
+  /* Step 2:  Check seedlen.  */
+  if (!seed && !seedlen)
+    ; /* No seed value given:  We are asked to generate it.  */
+  else if (!seed || seedlen < qbits/8)
+    return GPG_ERR_INV_ARG;
+  
+  /* Allocate a buffer to later compute SEED+some_increment and a few
+     helper variables.  */
+  seed_plus = gcry_malloc (seedlen < sizeof seed_help_buffer? 
+                           sizeof seed_help_buffer : seedlen);
+  if (!seed_plus)
+    {
+      ec = gpg_err_code_from_syserror ();
+      goto leave;
+    }
+  val_2   = mpi_alloc_set_ui (2);
+  value_w = gcry_mpi_new (pbits);
+  value_x = gcry_mpi_new (pbits);
+
+  /* Step 3: n = \lceil L / outlen \rceil - 1  */
+  value_n = (pbits + qbits - 1) / qbits - 1;
+  /* Step 4: b = L - 1 - (n * outlen)  */
+  value_b = pbits - 1 - (value_n * qbits);
+
+ restart:  
+  /* Generate Q.  */
+  for (;;)
+    {
+      /* Step 5:  Generate a (new) seed unless one has been supplied.  */
+      if (!seed)
+        {
+          seedlen = qbits/8;
+          gcry_assert (seedlen <= sizeof seed_help_buffer);
+          gcry_create_nonce (seed_help_buffer, seedlen);
+          seed = seed_help_buffer;
+        }
+      
+      /* Step 6:  U = hash(seed)  */
+      gcry_md_hash_buffer (hashalgo, value_u, seed, seedlen);
+
+      /* Step 7:  q = 2^{N-1} + U + 1 - (U mod 2)  */
+      if ( !(value_u[qbits/8-1] & 0x01) )
+        {
+          for (i=qbits/8-1; i >= 0; i--)
+            {
+              value_u[i]++;
+              if (value_u[i])
+                break;
+            }
+        }
+      gcry_mpi_release (prime_q); prime_q = NULL;
+      ec = gpg_err_code (gcry_mpi_scan (&prime_q, GCRYMPI_FMT_USG, 
+                                        value_u, sizeof value_u, NULL));
+      if (ec)
+        goto leave;
+      mpi_set_highbit (prime_q, qbits-1 );
+      
+      /* Step 8:  Test whether Q is prime using 64 round of Rabin-Miller.
+                  According to table C.1 this is sufficient for all
+                  supported prime sizes (i.e. up 3072/256).  */
+      if (check_prime (prime_q, val_2, 64, NULL, NULL))
+        break; /* Yes, Q is prime.  */
+
+      /* Step 8.  */
+      seed = NULL;  /* Force a new seed at Step 5.  */
+    }
+  
+  /* Step 11.  Note that we do no use an explicit offset but increment
+     SEED_PLUS accordingly.  */
+  memcpy (seed_plus, seed, seedlen);
+  counter = 0;
+
+  /* Generate P. */
+  prime_p = gcry_mpi_new (pbits);
+  for (;;)
+    {
+      /* Step 11.1: For j = 0,...n let 
+                      V_j = hash(seed+offset+j)  
+         Step 11.2: W = V_0 + V_1*2^outlen + 
+                            ... 
+                            + V_{n-1}*2^{(n-1)*outlen}
+                            + (V_{n} mod 2^b)*2^{n*outlen}                
+       */
+      mpi_set_ui (value_w, 0);
+      for (value_j=0; value_j <= value_n; value_j++)
+        {
+          /* There is no need to have an explicit offset variable: In
+             the first round we shall have an offset of 1 and a j of
+             0.  This is achieved by incrementing SEED_PLUS here.  For
+             the next round offset is implicitly updated by using
+             SEED_PLUS again.  */
+          for (i=seedlen-1; i >= 0; i--)
+            {
+              seed_plus[i]++;
+              if (seed_plus[i])
+                break;
+            }
+          gcry_md_hash_buffer (GCRY_MD_SHA1, digest, seed_plus, seedlen);
+          
+          gcry_mpi_release (tmpval); tmpval = NULL;
+          ec = gpg_err_code (gcry_mpi_scan (&tmpval, GCRYMPI_FMT_USG,
+                                            digest, sizeof digest, NULL));
+          if (ec)
+            goto leave;
+          if (value_j == value_n)
+            mpi_clear_highbit (tmpval, value_b); /* (V_n mod 2^b) */
+          mpi_lshift (tmpval, tmpval, value_j*qbits);
+          mpi_add (value_w, value_w, tmpval);
+        }
+
+      /* Step 11.3: X = W + 2^{L-1}  */
+      mpi_set_ui (value_x, 0);
+      mpi_set_highbit (value_x, pbits-1);
+      mpi_add (value_x, value_x, value_w);
+
+      /* Step 11.4:  c = X mod 2q  */
+      mpi_mul_2exp (tmpval, prime_q, 1);
+      mpi_mod (tmpval, value_x, tmpval);
+
+      /* Step 11.5:  p = X - (c - 1)  */
+      mpi_sub_ui (tmpval, tmpval, 1);
+      mpi_sub (prime_p, value_x, tmpval);
+
+      /* Step 11.6: If  p < 2^{L-1}  skip the primality test.  */
+      /* Step 11.7 and 11.8: Primality test.  */
+      if (mpi_get_nbits (prime_p) >= pbits-1
+          && check_prime (prime_p, val_2, 64, NULL, NULL) )
+        break; /* Yes, P is prime, continue with Step 15.  */
+      
+      /* Step 11.9: counter = counter + 1, offset = offset + n + 1.
+                    If counter >= 4L  goto Step 5.  */
+      counter++;
+      if (counter >= 4*pbits)
+        goto restart;
+    }
+
+  /* Step 12:  Save p, q, counter and seed.  */
+  log_debug ("fips186-3 pbits p=%u q=%u counter=%d\n",
+             mpi_get_nbits (prime_p), mpi_get_nbits (prime_q), counter);
+  log_printhex("fips186-3 seed:", seed, seedlen);
+  log_mpidump ("fips186-3 prime p", prime_p);
+  log_mpidump ("fips186-3 prime q", prime_q);
+  if (r_q)
+    {
+      *r_q = prime_q;
+      prime_q = NULL;
+    }
+  if (r_p)
+    {
+      *r_p = prime_p;
+      prime_p = NULL;
+    }
+  if (r_counter)
+    *r_counter = counter;
+  if (r_seed && r_seedlen)
+    {
+      memcpy (seed_plus, seed, seedlen);
+      *r_seed = seed_plus;
+      seed_plus = NULL;
+      *r_seedlen = seedlen;
+    }
+  if (r_hashalgo)
+    *r_hashalgo = hashalgo;
+
+ leave:
+  gcry_mpi_release (tmpval);
+  gcry_mpi_release (value_x);
+  gcry_mpi_release (value_w);
+  gcry_mpi_release (prime_p);
+  gcry_mpi_release (prime_q);
+  gcry_free (seed_plus);
+  gcry_mpi_release (val_2);
+  return ec;
+}
+