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path: root/pwmanager/libcrypt/cipher/primegen.c
authorzautrix <zautrix>2004-10-19 20:16:14 (UTC)
committer zautrix <zautrix>2004-10-19 20:16:14 (UTC)
commiteca49bb06a71980ef61d078904573f25890fc7f2 (patch) (side-by-side diff)
treec5338e3b12430248979a9ac2c1c7e6646ea9ecdf /pwmanager/libcrypt/cipher/primegen.c
parent53cc32b6e7b1f672bf91b2baf2df6c1e8baf3e0a (diff)
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Initial revision
Diffstat (limited to 'pwmanager/libcrypt/cipher/primegen.c') (more/less context) (ignore whitespace changes)
-rw-r--r--pwmanager/libcrypt/cipher/primegen.c1028
1 files changed, 1028 insertions, 0 deletions
diff --git a/pwmanager/libcrypt/cipher/primegen.c b/pwmanager/libcrypt/cipher/primegen.c
new file mode 100644
index 0000000..afd435e
--- a/dev/null
+++ b/pwmanager/libcrypt/cipher/primegen.c
@@ -0,0 +1,1028 @@
+/* primegen.c - prime number generator
+ * Copyright (C) 1998, 2000, 2001, 2002, 2003
+ * 2004 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
+ *
+ * ***********************************************************************
+ * The algorithm used to generate practically save primes is due to
+ * Lim and Lee as described in the CRYPTO '97 proceedings (ISBN3540633847)
+ * page 260.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <errno.h>
+
+#include "g10lib.h"
+#include "mpi.h"
+#include "cipher.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,
+ gcry_prime_check_func_t cb_func, void *cb_arg );
+static int is_prime( gcry_mpi_t n, int steps, 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;
+
+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,
+ int (*extra_check)(void*, gcry_mpi_t),
+ void *extra_check_arg)
+{
+ gcry_mpi_t prime;
+
+ prime = gen_prime( nbits, 1, 2, extra_check, extra_check_arg);
+ progress('\n');
+ return prime;
+}
+
+gcry_mpi_t
+_gcry_generate_public_prime( unsigned int nbits,
+ int (*extra_check)(void*, gcry_mpi_t),
+ void *extra_check_arg)
+{
+ gcry_mpi_t prime;
+
+ prime = gen_prime( nbits, 0, 2, extra_check, extra_check_arg );
+ progress('\n');
+ return prime;
+}
+
+
+/****************
+ * We do not need to use the strongest RNG because we gain no extra
+ * security from it - The prime number is public and we could also
+ * offer the factors for those who are willing to check that it is
+ * indeed a strong prime. With ALL_FACTORS set to true all afcors of
+ * prime-1 are returned in FACTORS.
+ *
+ * mode 0: Standard
+ * 1: Make sure that at least one factor is of size qbits.
+ */
+static gcry_err_code_t
+prime_generate_internal (int mode,
+ 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_mpi_t *pool = NULL; /* Pool of primes. */
+ 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(). */
+ 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;
+
+ /* If QBITS is not given, assume a reasonable value. */
+ if (!qbits)
+ qbits = pbits / 3;
+
+ req_qbits = qbits;
+
+ /* Find number of needed prime factors. */
+ for (n = 1; (pbits - qbits - 1) / n >= qbits; n++)
+ ;
+ n--;
+
+ val_2 = mpi_alloc_set_ui (2);
+
+ if ((! n) || ((mode == 1) && (n < 2)))
+ {
+ err = GPG_ERR_INV_ARG;
+ goto leave;
+ }
+
+ if (mode == 1)
+ {
+ n--;
+ 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);
+
+ prime = gcry_mpi_new (pbits);
+
+ /* Generate first prime factor. */
+ q = gen_prime (qbits, is_secret, randomlevel, NULL, NULL);
+
+ if (mode == 1)
+ q_factor = gen_prime (req_qbits, is_secret, randomlevel, NULL, NULL);
+
+ /* Allocate an array to hold the factors + 2 for later usage. */
+ factors = gcry_calloc (n + 2, sizeof (*factors));
+ if (!factors)
+ {
+ err = gpg_err_code_from_errno (errno);
+ goto leave;
+ }
+
+ /* Make a pool of 3n+5 primes (this is an arbitrary value). */
+ m = n * 3 + 5;
+ if (mode == 1) /* Need some more (for e.g. DSA). */
+ m += 5;
+ if (m < 25)
+ m = 25;
+ pool = gcry_calloc (m , sizeof (*pool));
+ if (! pool)
+ {
+ err = gpg_err_code_from_errno (errno);
+ goto leave;
+ }
+
+ /* Permutate over the pool of primes. */
+ do
+ {
+ next_try:
+ if (! perms)
+ {
+ /* Allocate new 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;
+ }
+ for(i = 0; i < n; i++)
+ {
+ perms[i] = 1;
+ pool[i] = gen_prime (fbits, is_secret,
+ randomlevel, NULL, NULL);
+ factors[i] = pool[i];
+ }
+ }
+ else
+ {
+ m_out_of_n (perms, n, m);
+ for (i = j = 0; (i < m) && (j < n); i++)
+ if (perms[i])
+ {
+ if(! pool[i])
+ pool[i] = gen_prime (fbits, 0, 1, NULL, NULL);
+ factors[j++] = pool[i];
+ }
+ if (i == n)
+ {
+ gcry_free (perms);
+ perms = NULL;
+ progress ('!');
+ goto next_try; /* Allocate new primes. */
+ }
+ }
+
+ /* 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 (mode == 1)
+ 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, 0, 0, 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, 0, 0, NULL, NULL);
+ goto next_try;
+ }
+ }
+ else
+ count2 = 0;
+ }
+ while (! ((nprime == pbits) && check_prime (prime, val_2, cb_func, cb_arg)));
+
+ if (DBG_CIPHER)
+ {
+ progress ('\n');
+ log_mpidump ("prime : ", prime);
+ log_mpidump ("factor q: ", q);
+ if (mode == 1)
+ 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 (mode == 1)
+ 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 (mode == 1)
+ factors_new[i++] = mpi_copy (q_factor);
+ for(j=0; j < n; j++)
+ factors_new[i++] = mpi_copy (factors[j]);
+ }
+ else
+ {
+ i = 0;
+ if (mode == 1)
+ {
+ 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 (mode == 1)
+ 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)
+ {
+ for(i = 0; i < m; i++)
+ mpi_free (pool[i]);
+ gcry_free (pool);
+ }
+ 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;
+}
+
+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, &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 x, step;
+ unsigned 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
+ */
+static int
+check_prime( gcry_mpi_t prime, gcry_mpi_t val_2,
+ gcry_prime_check_func_t cb_func, void *cb_arg)
+{
+ int i;
+ unsigned int x;
+ 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, 5, &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, 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 );
+
+ 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 );
+ }
+ 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;
+}
+
+
+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;
+
+ if( m == 1 )
+ {
+ /* Special case. */
+ 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:
+ 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, &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. */
+
+ if (! check_prime (x, val_2, 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);
+ }
+}