Import LibreSSL v2.4.2 to vendor branch

[dragonfly.git] / crypto / libressl / crypto / bn / bn_prime.c

/* $OpenBSD: bn_prime.c,v 1.14 2015/10/21 19:02:22 miod Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */
/* ====================================================================
 * Copyright (c) 1998-2001 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include <time.h>

#include <openssl/err.h>

#include "bn_lcl.h"

/* NB: these functions have been "upgraded", the deprecated versions (which are
 * compatibility wrappers using these functions) are in bn_depr.c.
 * - Geoff
 */

/* The quick sieve algorithm approach to weeding out primes is
 * Philip Zimmermann's, as implemented in PGP.  I have had a read of
 * his comments and implemented my own version.
 */
#include "bn_prime.h"

static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
    const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont);
static int probable_prime(BIGNUM *rnd, int bits);
static int probable_prime_dh(BIGNUM *rnd, int bits,
    const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
static int probable_prime_dh_safe(BIGNUM *rnd, int bits,
    const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);

int
BN_GENCB_call(BN_GENCB *cb, int a, int b)
{
        /* No callback means continue */
        if (!cb)
                return 1;
        switch (cb->ver) {
        case 1:
                /* Deprecated-style callbacks */
                if (!cb->cb.cb_1)
                        return 1;
                cb->cb.cb_1(a, b, cb->arg);
                return 1;
        case 2:
                /* New-style callbacks */
                return cb->cb.cb_2(a, b, cb);
        default:
                break;
        }
        /* Unrecognised callback type */
        return 0;
}

int
BN_generate_prime_ex(BIGNUM *ret, int bits, int safe, const BIGNUM *add,
    const BIGNUM *rem, BN_GENCB *cb)
{
        BIGNUM *t;
        int found = 0;
        int i, j, c1 = 0;
        BN_CTX *ctx;
        int checks;

        if (bits < 2 || (bits == 2 && safe)) {
                /*
                 * There are no prime numbers smaller than 2, and the smallest
                 * safe prime (7) spans three bits.
                 */
                BNerr(BN_F_BN_GENERATE_PRIME_EX, BN_R_BITS_TOO_SMALL);
                return 0;
        }

        ctx = BN_CTX_new();
        if (ctx == NULL)
                goto err;
        BN_CTX_start(ctx);
        if ((t = BN_CTX_get(ctx)) == NULL)
                goto err;

        checks = BN_prime_checks_for_size(bits);

loop:
        /* make a random number and set the top and bottom bits */
        if (add == NULL) {
                if (!probable_prime(ret, bits))
                        goto err;
        } else {
                if (safe) {
                        if (!probable_prime_dh_safe(ret, bits, add, rem, ctx))
                                goto err;
                } else {
                        if (!probable_prime_dh(ret, bits, add, rem, ctx))
                                goto err;
                }
        }
        /* if (BN_mod_word(ret,(BN_ULONG)3) == 1) goto loop; */
        if (!BN_GENCB_call(cb, 0, c1++))
                /* aborted */
                goto err;

        if (!safe) {
                i = BN_is_prime_fasttest_ex(ret, checks, ctx, 0, cb);
                if (i == -1)
                        goto err;
                if (i == 0)
                        goto loop;
        } else {
                /* for "safe prime" generation,
                 * check that (p-1)/2 is prime.
                 * Since a prime is odd, We just
                 * need to divide by 2 */
                if (!BN_rshift1(t, ret))
                        goto err;

                for (i = 0; i < checks; i++) {
                        j = BN_is_prime_fasttest_ex(ret, 1, ctx, 0, cb);
                        if (j == -1)
                                goto err;
                        if (j == 0)
                                goto loop;

                        j = BN_is_prime_fasttest_ex(t, 1, ctx, 0, cb);
                        if (j == -1)
                                goto err;
                        if (j == 0)
                                goto loop;

                        if (!BN_GENCB_call(cb, 2, c1 - 1))
                                goto err;
                        /* We have a safe prime test pass */
                }
        }
        /* we have a prime :-) */
        found = 1;

err:
        if (ctx != NULL) {
                BN_CTX_end(ctx);
                BN_CTX_free(ctx);
        }
        bn_check_top(ret);
        return found;
}

int
BN_is_prime_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, BN_GENCB *cb)
{
        return BN_is_prime_fasttest_ex(a, checks, ctx_passed, 0, cb);
}

int
BN_is_prime_fasttest_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed,
    int do_trial_division, BN_GENCB *cb)
{
        int i, j, ret = -1;
        int k;
        BN_CTX *ctx = NULL;
        BIGNUM *A1, *A1_odd, *check; /* taken from ctx */
        BN_MONT_CTX *mont = NULL;
        const BIGNUM *A = NULL;

        if (BN_cmp(a, BN_value_one()) <= 0)
                return 0;

        if (checks == BN_prime_checks)
                checks = BN_prime_checks_for_size(BN_num_bits(a));

        /* first look for small factors */
        if (!BN_is_odd(a))
                /* a is even => a is prime if and only if a == 2 */
                return BN_is_word(a, 2);
        if (do_trial_division) {
                for (i = 1; i < NUMPRIMES; i++) {
                        BN_ULONG mod = BN_mod_word(a, primes[i]);
                        if (mod == (BN_ULONG)-1)
                                goto err;
                        if (mod == 0)
                                return 0;
                }
                if (!BN_GENCB_call(cb, 1, -1))
                        goto err;
        }

        if (ctx_passed != NULL)
                ctx = ctx_passed;
        else if ((ctx = BN_CTX_new()) == NULL)
                goto err;
        BN_CTX_start(ctx);

        /* A := abs(a) */
        if (a->neg) {
                BIGNUM *t;
                if ((t = BN_CTX_get(ctx)) == NULL)
                        goto err;
                BN_copy(t, a);
                t->neg = 0;
                A = t;
        } else
                A = a;
        if ((A1 = BN_CTX_get(ctx)) == NULL)
                goto err;
        if ((A1_odd = BN_CTX_get(ctx)) == NULL)
                goto err;
        if ((check = BN_CTX_get(ctx)) == NULL)
                goto err;

        /* compute A1 := A - 1 */
        if (!BN_copy(A1, A))
                goto err;
        if (!BN_sub_word(A1, 1))
                goto err;
        if (BN_is_zero(A1)) {
                ret = 0;
                goto err;
        }

        /* write  A1  as  A1_odd * 2^k */
        k = 1;
        while (!BN_is_bit_set(A1, k))
                k++;
        if (!BN_rshift(A1_odd, A1, k))
                goto err;

        /* Montgomery setup for computations mod A */
        mont = BN_MONT_CTX_new();
        if (mont == NULL)
                goto err;
        if (!BN_MONT_CTX_set(mont, A, ctx))
                goto err;

        for (i = 0; i < checks; i++) {
                if (!BN_pseudo_rand_range(check, A1))
                        goto err;
                if (!BN_add_word(check, 1))
                        goto err;
                /* now 1 <= check < A */

                j = witness(check, A, A1, A1_odd, k, ctx, mont);
                if (j == -1)
                        goto err;
                if (j) {
                        ret = 0;
                        goto err;
                }
                if (!BN_GENCB_call(cb, 1, i))
                        goto err;
        }
        ret = 1;

err:
        if (ctx != NULL) {
                BN_CTX_end(ctx);
                if (ctx_passed == NULL)
                        BN_CTX_free(ctx);
        }
        BN_MONT_CTX_free(mont);

        return (ret);
}

static int
witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1, const BIGNUM *a1_odd,
    int k, BN_CTX *ctx, BN_MONT_CTX *mont)
{
        if (!BN_mod_exp_mont(w, w, a1_odd, a, ctx, mont))
                /* w := w^a1_odd mod a */
                return -1;
        if (BN_is_one(w))
                return 0; /* probably prime */
        if (BN_cmp(w, a1) == 0)
                return 0; /* w == -1 (mod a),  'a' is probably prime */
        while (--k) {
                if (!BN_mod_mul(w, w, w, a, ctx)) /* w := w^2 mod a */
                        return -1;
                if (BN_is_one(w))
                        return 1; /* 'a' is composite, otherwise a previous 'w' would
                                   * have been == -1 (mod 'a') */
                if (BN_cmp(w, a1) == 0)
                        return 0; /* w == -1 (mod a), 'a' is probably prime */
        }
        /* If we get here, 'w' is the (a-1)/2-th power of the original 'w',
         * and it is neither -1 nor +1 -- so 'a' cannot be prime */
        bn_check_top(w);
        return 1;
}

static int
probable_prime(BIGNUM *rnd, int bits)
{
        int i;
        prime_t mods[NUMPRIMES];
        BN_ULONG delta, maxdelta;

again:
        if (!BN_rand(rnd, bits, 1, 1))
                return (0);
        /* we now have a random number 'rand' to test. */
        for (i = 1; i < NUMPRIMES; i++) {
                BN_ULONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]);
                if (mod == (BN_ULONG)-1)
                        return (0);
                mods[i] = (prime_t)mod;
        }
        maxdelta = BN_MASK2 - primes[NUMPRIMES - 1];
        delta = 0;
loop:
        for (i = 1; i < NUMPRIMES; i++) {
                /* check that rnd is not a prime and also
                 * that gcd(rnd-1,primes) == 1 (except for 2) */
                if (((mods[i] + delta) % primes[i]) <= 1) {
                        delta += 2;
                        if (delta > maxdelta)
                                goto again;
                        goto loop;
                }
        }
        if (!BN_add_word(rnd, delta))
                return (0);
        bn_check_top(rnd);
        return (1);
}

static int
probable_prime_dh(BIGNUM *rnd, int bits, const BIGNUM *add, const BIGNUM *rem,
    BN_CTX *ctx)
{
        int i, ret = 0;
        BIGNUM *t1;

        BN_CTX_start(ctx);
        if ((t1 = BN_CTX_get(ctx)) == NULL)
                goto err;

        if (!BN_rand(rnd, bits, 0, 1))
                goto err;

        /* we need ((rnd-rem) % add) == 0 */

        if (!BN_mod(t1, rnd, add, ctx))
                goto err;
        if (!BN_sub(rnd, rnd, t1))
                goto err;
        if (rem == NULL) {
                if (!BN_add_word(rnd, 1))
                        goto err;
        } else {
                if (!BN_add(rnd, rnd, rem))
                        goto err;
        }

        /* we now have a random number 'rand' to test. */

loop:
        for (i = 1; i < NUMPRIMES; i++) {
                /* check that rnd is a prime */
                BN_LONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]);
                if (mod == (BN_ULONG)-1)
                        goto err;
                if (mod <= 1) {
                        if (!BN_add(rnd, rnd, add))
                                goto err;
                        goto loop;
                }
        }
        ret = 1;

err:
        BN_CTX_end(ctx);
        bn_check_top(rnd);
        return (ret);
}

static int
probable_prime_dh_safe(BIGNUM *p, int bits, const BIGNUM *padd,
    const BIGNUM *rem, BN_CTX *ctx)
{
        int i, ret = 0;
        BIGNUM *t1, *qadd, *q;

        bits--;
        BN_CTX_start(ctx);
        if ((t1 = BN_CTX_get(ctx)) == NULL)
                goto err;
        if ((q = BN_CTX_get(ctx)) == NULL)
                goto err;
        if ((qadd = BN_CTX_get(ctx)) == NULL)
                goto err;

        if (!BN_rshift1(qadd, padd))
                goto err;

        if (!BN_rand(q, bits, 0, 1))
                goto err;

        /* we need ((rnd-rem) % add) == 0 */
        if (!BN_mod(t1, q,qadd, ctx))
                goto err;
        if (!BN_sub(q, q, t1))
                goto err;
        if (rem == NULL) {
                if (!BN_add_word(q, 1))
                        goto err;
        } else {
                if (!BN_rshift1(t1, rem))
                        goto err;
                if (!BN_add(q, q, t1))
                        goto err;
        }

        /* we now have a random number 'rand' to test. */
        if (!BN_lshift1(p, q))
                goto err;
        if (!BN_add_word(p, 1))
                goto err;

loop:
        for (i = 1; i < NUMPRIMES; i++) {
                /* check that p and q are prime */
                /* check that for p and q
                 * gcd(p-1,primes) == 1 (except for 2) */
                BN_ULONG pmod = BN_mod_word(p, (BN_ULONG)primes[i]);
                BN_ULONG qmod = BN_mod_word(q, (BN_ULONG)primes[i]);
                if (pmod == (BN_ULONG)-1 || qmod == (BN_ULONG)-1)
                        goto err;
                if (pmod == 0 || qmod == 0) {
                        if (!BN_add(p, p, padd))
                                goto err;
                        if (!BN_add(q, q, qadd))
                                goto err;
                        goto loop;
                }
        }
        ret = 1;

err:
        BN_CTX_end(ctx);
        bn_check_top(p);
        return (ret);
}