249 lines
5.8 KiB
C
249 lines
5.8 KiB
C
/*
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* Copyright 2011-2021 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#define OPENSSL_SUPPRESS_DEPRECATED
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#include <stdio.h>
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#include <openssl/bn.h>
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#include "bn_local.h"
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/* X9.31 routines for prime derivation */
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/*
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* X9.31 prime derivation. This is used to generate the primes pi (p1, p2,
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* q1, q2) from a parameter Xpi by checking successive odd integers.
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*/
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static int bn_x931_derive_pi(BIGNUM *pi, const BIGNUM *Xpi, BN_CTX *ctx,
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BN_GENCB *cb)
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{
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int i = 0, is_prime;
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if (!BN_copy(pi, Xpi))
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return 0;
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if (!BN_is_odd(pi) && !BN_add_word(pi, 1))
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return 0;
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for (;;) {
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i++;
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BN_GENCB_call(cb, 0, i);
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/* NB 27 MR is specified in X9.31 */
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is_prime = BN_check_prime(pi, ctx, cb);
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if (is_prime < 0)
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return 0;
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if (is_prime)
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break;
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if (!BN_add_word(pi, 2))
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return 0;
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}
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BN_GENCB_call(cb, 2, i);
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return 1;
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}
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/*
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* This is the main X9.31 prime derivation function. From parameters Xp1, Xp2
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* and Xp derive the prime p. If the parameters p1 or p2 are not NULL they
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* will be returned too: this is needed for testing.
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*/
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int BN_X931_derive_prime_ex(BIGNUM *p, BIGNUM *p1, BIGNUM *p2,
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const BIGNUM *Xp, const BIGNUM *Xp1,
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const BIGNUM *Xp2, const BIGNUM *e, BN_CTX *ctx,
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BN_GENCB *cb)
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{
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int ret = 0;
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BIGNUM *t, *p1p2, *pm1;
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/* Only even e supported */
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if (!BN_is_odd(e))
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return 0;
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BN_CTX_start(ctx);
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if (p1 == NULL)
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p1 = BN_CTX_get(ctx);
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if (p2 == NULL)
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p2 = BN_CTX_get(ctx);
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t = BN_CTX_get(ctx);
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p1p2 = BN_CTX_get(ctx);
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pm1 = BN_CTX_get(ctx);
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if (pm1 == NULL)
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goto err;
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if (!bn_x931_derive_pi(p1, Xp1, ctx, cb))
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goto err;
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if (!bn_x931_derive_pi(p2, Xp2, ctx, cb))
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goto err;
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if (!BN_mul(p1p2, p1, p2, ctx))
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goto err;
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/* First set p to value of Rp */
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if (!BN_mod_inverse(p, p2, p1, ctx))
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goto err;
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if (!BN_mul(p, p, p2, ctx))
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goto err;
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if (!BN_mod_inverse(t, p1, p2, ctx))
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goto err;
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if (!BN_mul(t, t, p1, ctx))
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goto err;
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if (!BN_sub(p, p, t))
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goto err;
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if (p->neg && !BN_add(p, p, p1p2))
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goto err;
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/* p now equals Rp */
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if (!BN_mod_sub(p, p, Xp, p1p2, ctx))
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goto err;
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if (!BN_add(p, p, Xp))
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goto err;
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/* p now equals Yp0 */
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for (;;) {
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int i = 1;
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BN_GENCB_call(cb, 0, i++);
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if (!BN_copy(pm1, p))
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goto err;
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if (!BN_sub_word(pm1, 1))
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goto err;
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if (!BN_gcd(t, pm1, e, ctx))
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goto err;
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if (BN_is_one(t)) {
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/*
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* X9.31 specifies 8 MR and 1 Lucas test or any prime test
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* offering similar or better guarantees 50 MR is considerably
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* better.
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*/
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int r = BN_check_prime(p, ctx, cb);
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if (r < 0)
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goto err;
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if (r)
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break;
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}
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if (!BN_add(p, p, p1p2))
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goto err;
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}
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BN_GENCB_call(cb, 3, 0);
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ret = 1;
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err:
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BN_CTX_end(ctx);
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return ret;
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}
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/*
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* Generate pair of parameters Xp, Xq for X9.31 prime generation. Note: nbits
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* parameter is sum of number of bits in both.
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*/
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int BN_X931_generate_Xpq(BIGNUM *Xp, BIGNUM *Xq, int nbits, BN_CTX *ctx)
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{
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BIGNUM *t;
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int i;
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/*
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* Number of bits for each prime is of the form 512+128s for s = 0, 1,
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* ...
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*/
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if ((nbits < 1024) || (nbits & 0xff))
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return 0;
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nbits >>= 1;
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/*
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* The random value Xp must be between sqrt(2) * 2^(nbits-1) and 2^nbits
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* - 1. By setting the top two bits we ensure that the lower bound is
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* exceeded.
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*/
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if (!BN_priv_rand_ex(Xp, nbits, BN_RAND_TOP_TWO, BN_RAND_BOTTOM_ANY, 0,
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ctx))
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return 0;
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BN_CTX_start(ctx);
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t = BN_CTX_get(ctx);
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if (t == NULL)
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goto err;
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for (i = 0; i < 1000; i++) {
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if (!BN_priv_rand_ex(Xq, nbits, BN_RAND_TOP_TWO, BN_RAND_BOTTOM_ANY, 0,
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ctx))
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goto err;
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/* Check that |Xp - Xq| > 2^(nbits - 100) */
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if (!BN_sub(t, Xp, Xq))
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goto err;
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if (BN_num_bits(t) > (nbits - 100))
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break;
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}
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BN_CTX_end(ctx);
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if (i < 1000)
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return 1;
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return 0;
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err:
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BN_CTX_end(ctx);
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return 0;
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}
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/*
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* Generate primes using X9.31 algorithm. Of the values p, p1, p2, Xp1 and
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* Xp2 only 'p' needs to be non-NULL. If any of the others are not NULL the
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* relevant parameter will be stored in it. Due to the fact that |Xp - Xq| >
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* 2^(nbits - 100) must be satisfied Xp and Xq are generated using the
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* previous function and supplied as input.
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*/
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int BN_X931_generate_prime_ex(BIGNUM *p, BIGNUM *p1, BIGNUM *p2,
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BIGNUM *Xp1, BIGNUM *Xp2,
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const BIGNUM *Xp,
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const BIGNUM *e, BN_CTX *ctx, BN_GENCB *cb)
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{
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int ret = 0;
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BN_CTX_start(ctx);
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if (Xp1 == NULL)
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Xp1 = BN_CTX_get(ctx);
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if (Xp2 == NULL)
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Xp2 = BN_CTX_get(ctx);
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if (Xp1 == NULL || Xp2 == NULL)
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goto error;
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if (!BN_priv_rand_ex(Xp1, 101, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY, 0, ctx))
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goto error;
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if (!BN_priv_rand_ex(Xp2, 101, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY, 0, ctx))
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goto error;
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if (!BN_X931_derive_prime_ex(p, p1, p2, Xp, Xp1, Xp2, e, ctx, cb))
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goto error;
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ret = 1;
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error:
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BN_CTX_end(ctx);
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return ret;
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}
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