/* 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.] */ #include <openssl_grpc/dh.h> #include <openssl_grpc/bn.h> int DH_check_pub_key(const DH *dh, const BIGNUM *pub_key, int *out_flags) { *out_flags = 0; BN_CTX *ctx = BN_CTX_new(); if (ctx == NULL) { return 0; } BN_CTX_start(ctx); int ok = 0; // Check |pub_key| is greater than 1. BIGNUM *tmp = BN_CTX_get(ctx); if (tmp == NULL || !BN_set_word(tmp, 1)) { goto err; } if (BN_cmp(pub_key, tmp) <= 0) { *out_flags |= DH_CHECK_PUBKEY_TOO_SMALL; } // Check |pub_key| is less than |dh->p| - 1. if (!BN_copy(tmp, dh->p) || !BN_sub_word(tmp, 1)) { goto err; } if (BN_cmp(pub_key, tmp) >= 0) { *out_flags |= DH_CHECK_PUBKEY_TOO_LARGE; } if (dh->q != NULL) { // Check |pub_key|^|dh->q| is 1 mod |dh->p|. This is necessary for RFC 5114 // groups which are not safe primes but pick a generator on a prime-order // subgroup of size |dh->q|. if (!BN_mod_exp_mont(tmp, pub_key, dh->q, dh->p, ctx, NULL)) { goto err; } if (!BN_is_one(tmp)) { *out_flags |= DH_CHECK_PUBKEY_INVALID; } } ok = 1; err: BN_CTX_end(ctx); BN_CTX_free(ctx); return ok; } int DH_check(const DH *dh, int *out_flags) { // Check that p is a safe prime and if g is 2, 3 or 5, check that it is a // suitable generator where: // for 2, p mod 24 == 11 // for 3, p mod 12 == 5 // for 5, p mod 10 == 3 or 7 // should hold. int ok = 0, r; BN_CTX *ctx = NULL; BN_ULONG l; BIGNUM *t1 = NULL, *t2 = NULL; *out_flags = 0; ctx = BN_CTX_new(); if (ctx == NULL) { goto err; } BN_CTX_start(ctx); t1 = BN_CTX_get(ctx); if (t1 == NULL) { goto err; } t2 = BN_CTX_get(ctx); if (t2 == NULL) { goto err; } if (dh->q) { if (BN_cmp(dh->g, BN_value_one()) <= 0) { *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; } else if (BN_cmp(dh->g, dh->p) >= 0) { *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; } else { // Check g^q == 1 mod p if (!BN_mod_exp_mont(t1, dh->g, dh->q, dh->p, ctx, NULL)) { goto err; } if (!BN_is_one(t1)) { *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; } } r = BN_is_prime_ex(dh->q, BN_prime_checks_for_validation, ctx, NULL); if (r < 0) { goto err; } if (!r) { *out_flags |= DH_CHECK_Q_NOT_PRIME; } // Check p == 1 mod q i.e. q divides p - 1 if (!BN_div(t1, t2, dh->p, dh->q, ctx)) { goto err; } if (!BN_is_one(t2)) { *out_flags |= DH_CHECK_INVALID_Q_VALUE; } if (dh->j && BN_cmp(dh->j, t1)) { *out_flags |= DH_CHECK_INVALID_J_VALUE; } } else if (BN_is_word(dh->g, DH_GENERATOR_2)) { l = BN_mod_word(dh->p, 24); if (l == (BN_ULONG)-1) { goto err; } if (l != 11) { *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; } } else if (BN_is_word(dh->g, DH_GENERATOR_5)) { l = BN_mod_word(dh->p, 10); if (l == (BN_ULONG)-1) { goto err; } if (l != 3 && l != 7) { *out_flags |= DH_CHECK_NOT_SUITABLE_GENERATOR; } } else { *out_flags |= DH_CHECK_UNABLE_TO_CHECK_GENERATOR; } r = BN_is_prime_ex(dh->p, BN_prime_checks_for_validation, ctx, NULL); if (r < 0) { goto err; } if (!r) { *out_flags |= DH_CHECK_P_NOT_PRIME; } else if (!dh->q) { if (!BN_rshift1(t1, dh->p)) { goto err; } r = BN_is_prime_ex(t1, BN_prime_checks_for_validation, ctx, NULL); if (r < 0) { goto err; } if (!r) { *out_flags |= DH_CHECK_P_NOT_SAFE_PRIME; } } ok = 1; err: if (ctx != NULL) { BN_CTX_end(ctx); BN_CTX_free(ctx); } return ok; }