X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=crypto%2Fdsa%2Fdsa_ossl.c;h=cefda5a450fa5175b51a8a643af592c399c5b35b;hb=c6991655c4ce4764861dd5bdf64a92be5f54dbb3;hp=96f5d6fed166a5fb6de1f4a85a5aa2db25efbc92;hpb=474e469bbd056aebcf7e7d3207ef820f2faed4ce;p=oweals%2Fopenssl.git diff --git a/crypto/dsa/dsa_ossl.c b/crypto/dsa/dsa_ossl.c index 96f5d6fed1..cefda5a450 100644 --- a/crypto/dsa/dsa_ossl.c +++ b/crypto/dsa/dsa_ossl.c @@ -1,69 +1,18 @@ -/* crypto/dsa/dsa_ossl.c */ -/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) - * All rights reserved. +/* + * Copyright 1995-2019 The OpenSSL Project Authors. 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.] + * Licensed under the OpenSSL license (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html */ -/* Original version from Steven Schoch */ - #include -#include "cryptlib.h" +#include "internal/cryptlib.h" +#include "internal/bn_int.h" #include #include -#include -#include +#include "dsa_locl.h" #include static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa); @@ -75,6 +24,8 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, DSA *dsa); static int dsa_init(DSA *dsa); static int dsa_finish(DSA *dsa); +static BIGNUM *dsa_mod_inverse_fermat(const BIGNUM *k, const BIGNUM *q, + BN_CTX *ctx); static DSA_METHOD openssl_dsa_meth = { "OpenSSL DSA method", @@ -91,41 +42,17 @@ static DSA_METHOD openssl_dsa_meth = { NULL }; -/*- - * These macro wrappers replace attempts to use the dsa_mod_exp() and - * bn_mod_exp() handlers in the DSA_METHOD structure. We avoid the problem of - * having a the macro work as an expression by bundling an "err_instr". So; - * - * if (!dsa->meth->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx, - * dsa->method_mont_p)) goto err; - * - * can be replaced by; - * - * DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, &k, dsa->p, ctx, - * dsa->method_mont_p); - */ +static const DSA_METHOD *default_DSA_method = &openssl_dsa_meth; -#define DSA_MOD_EXP(err_instr,dsa,rr,a1,p1,a2,p2,m,ctx,in_mont) \ - do { \ - int _tmp_res53; \ - if((dsa)->meth->dsa_mod_exp) \ - _tmp_res53 = (dsa)->meth->dsa_mod_exp((dsa), (rr), (a1), (p1), \ - (a2), (p2), (m), (ctx), (in_mont)); \ - else \ - _tmp_res53 = BN_mod_exp2_mont((rr), (a1), (p1), (a2), (p2), \ - (m), (ctx), (in_mont)); \ - if(!_tmp_res53) err_instr; \ - } while(0) -#define DSA_BN_MOD_EXP(err_instr,dsa,r,a,p,m,ctx,m_ctx) \ - do { \ - int _tmp_res53; \ - if((dsa)->meth->bn_mod_exp) \ - _tmp_res53 = (dsa)->meth->bn_mod_exp((dsa), (r), (a), (p), \ - (m), (ctx), (m_ctx)); \ - else \ - _tmp_res53 = BN_mod_exp_mont((r), (a), (p), (m), (ctx), (m_ctx)); \ - if(!_tmp_res53) err_instr; \ - } while(0) +void DSA_set_default_method(const DSA_METHOD *meth) +{ + default_DSA_method = meth; +} + +const DSA_METHOD *DSA_get_default_method(void) +{ + return default_DSA_method; +} const DSA_METHOD *DSA_OpenSSL(void) { @@ -134,41 +61,39 @@ const DSA_METHOD *DSA_OpenSSL(void) static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) { - BIGNUM *kinv = NULL, *r = NULL, *s = NULL; - BIGNUM *m; - BIGNUM *xr; + BIGNUM *kinv = NULL; + BIGNUM *m, *blind, *blindm, *tmp; BN_CTX *ctx = NULL; int reason = ERR_R_BN_LIB; DSA_SIG *ret = NULL; - int noredo = 0; + int rv = 0; - m = BN_new(); - xr = BN_new(); - if (!m || !xr) - goto err; - - if (!dsa->p || !dsa->q || !dsa->g) { + if (dsa->p == NULL || dsa->q == NULL || dsa->g == NULL) { reason = DSA_R_MISSING_PARAMETERS; goto err; } - s = BN_new(); - if (s == NULL) + ret = DSA_SIG_new(); + if (ret == NULL) goto err; + ret->r = BN_new(); + ret->s = BN_new(); + if (ret->r == NULL || ret->s == NULL) + goto err; + ctx = BN_CTX_new(); if (ctx == NULL) goto err; + m = BN_CTX_get(ctx); + blind = BN_CTX_get(ctx); + blindm = BN_CTX_get(ctx); + tmp = BN_CTX_get(ctx); + if (tmp == NULL) + goto err; + redo: - if ((dsa->kinv == NULL) || (dsa->r == NULL)) { - if (!dsa_sign_setup(dsa, ctx, &kinv, &r, dgst, dlen)) - goto err; - } else { - kinv = dsa->kinv; - dsa->kinv = NULL; - r = dsa->r; - dsa->r = NULL; - noredo = 1; - } + if (!dsa_sign_setup(dsa, ctx, &kinv, &ret->r, dgst, dlen)) + goto err; if (dlen > BN_num_bytes(dsa->q)) /* @@ -180,47 +105,68 @@ static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) if (BN_bin2bn(dgst, dlen, m) == NULL) goto err; - /* Compute s = inv(k) (m + xr) mod q */ - if (!BN_mod_mul(xr, dsa->priv_key, r, dsa->q, ctx)) - goto err; /* s = xr */ - if (!BN_add(s, xr, m)) - goto err; /* s = m + xr */ - if (BN_cmp(s, dsa->q) > 0) - if (!BN_sub(s, s, dsa->q)) + /* + * The normal signature calculation is: + * + * s := k^-1 * (m + r * priv_key) mod q + * + * We will blind this to protect against side channel attacks + * + * s := blind^-1 * k^-1 * (blind * m + blind * r * priv_key) mod q + */ + + /* Generate a blinding value */ + do { + if (!BN_priv_rand(blind, BN_num_bits(dsa->q) - 1, + BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY)) goto err; - if (!BN_mod_mul(s, s, kinv, dsa->q, ctx)) + } while (BN_is_zero(blind)); + BN_set_flags(blind, BN_FLG_CONSTTIME); + BN_set_flags(blindm, BN_FLG_CONSTTIME); + BN_set_flags(tmp, BN_FLG_CONSTTIME); + + /* tmp := blind * priv_key * r mod q */ + if (!BN_mod_mul(tmp, blind, dsa->priv_key, dsa->q, ctx)) + goto err; + if (!BN_mod_mul(tmp, tmp, ret->r, dsa->q, ctx)) goto err; - ret = DSA_SIG_new(); - if (ret == NULL) + /* blindm := blind * m mod q */ + if (!BN_mod_mul(blindm, blind, m, dsa->q, ctx)) + goto err; + + /* s : = (blind * priv_key * r) + (blind * m) mod q */ + if (!BN_mod_add_quick(ret->s, tmp, blindm, dsa->q)) + goto err; + + /* s := s * k^-1 mod q */ + if (!BN_mod_mul(ret->s, ret->s, kinv, dsa->q, ctx)) goto err; + + /* s:= s * blind^-1 mod q */ + if (BN_mod_inverse(blind, blind, dsa->q, ctx) == NULL) + goto err; + if (!BN_mod_mul(ret->s, ret->s, blind, dsa->q, ctx)) + goto err; + /* * Redo if r or s is zero as required by FIPS 186-3: this is very * unlikely. */ - if (BN_is_zero(r) || BN_is_zero(s)) { - if (noredo) { - reason = DSA_R_NEED_NEW_SETUP_VALUES; - goto err; - } + if (BN_is_zero(ret->r) || BN_is_zero(ret->s)) goto redo; - } - ret->r = r; - ret->s = s; + + rv = 1; err: - if (!ret) { + if (rv == 0) { DSAerr(DSA_F_DSA_DO_SIGN, reason); - BN_free(r); - BN_free(s); + DSA_SIG_free(ret); + ret = NULL; } - if (ctx != NULL) - BN_CTX_free(ctx); - BN_clear_free(m); - BN_clear_free(xr); - if (kinv != NULL) /* dsa->kinv is NULL now if we used it */ - BN_clear_free(kinv); - return (ret); + BN_CTX_free(ctx); + BN_clear_free(kinv); + return ret; } static int dsa_sign_setup_no_digest(DSA *dsa, BN_CTX *ctx_in, @@ -234,17 +180,25 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, const unsigned char *dgst, int dlen) { BN_CTX *ctx = NULL; - BIGNUM *k, *kq, *K, *kinv = NULL, *r = NULL; + BIGNUM *k, *kinv = NULL, *r = *rp; + BIGNUM *l; int ret = 0; + int q_bits, q_words; if (!dsa->p || !dsa->q || !dsa->g) { DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS); return 0; } + /* Reject obviously invalid parameters */ + if (BN_is_zero(dsa->p) || BN_is_zero(dsa->q) || BN_is_zero(dsa->g)) { + DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_INVALID_PARAMETERS); + return 0; + } + k = BN_new(); - kq = BN_new(); - if (!k || !kq) + l = BN_new(); + if (k == NULL || l == NULL) goto err; if (ctx_in == NULL) { @@ -253,7 +207,11 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, } else ctx = ctx_in; - if ((r = BN_new()) == NULL) + /* Preallocate space */ + q_bits = BN_num_bits(dsa->q); + q_words = bn_get_top(dsa->q); + if (!bn_wexpand(k, q_words + 2) + || !bn_wexpand(l, q_words + 2)) goto err; /* Get random k */ @@ -266,72 +224,68 @@ static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, if (!BN_generate_dsa_nonce(k, dsa->q, dsa->priv_key, dgst, dlen, ctx)) goto err; - } else if (!BN_rand_range(k, dsa->q)) + } else if (!BN_priv_rand_range(k, dsa->q)) goto err; } while (BN_is_zero(k)); - if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { - BN_set_flags(k, BN_FLG_CONSTTIME); - } + BN_set_flags(k, BN_FLG_CONSTTIME); + BN_set_flags(l, BN_FLG_CONSTTIME); if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { if (!BN_MONT_CTX_set_locked(&dsa->method_mont_p, - CRYPTO_LOCK_DSA, dsa->p, ctx)) + dsa->lock, dsa->p, ctx)) goto err; } /* Compute r = (g^k mod p) mod q */ - if ((dsa->flags & DSA_FLAG_NO_EXP_CONSTTIME) == 0) { - if (!BN_copy(kq, k)) - goto err; + /* + * We do not want timing information to leak the length of k, so we + * compute G^k using an equivalent scalar of fixed bit-length. + * + * We unconditionally perform both of these additions to prevent a + * small timing information leakage. We then choose the sum that is + * one bit longer than the modulus. + * + * There are some concerns about the efficacy of doing this. More + * specificly refer to the discussion starting with: + * https://github.com/openssl/openssl/pull/7486#discussion_r228323705 + * The fix is to rework BN so these gymnastics aren't required. + */ + if (!BN_add(l, k, dsa->q) + || !BN_add(k, l, dsa->q)) + goto err; - /* - * We do not want timing information to leak the length of k, so we - * compute g^k using an equivalent exponent of fixed length. (This - * is a kludge that we need because the BN_mod_exp_mont() does not - * let us specify the desired timing behaviour.) - */ + BN_consttime_swap(BN_is_bit_set(l, q_bits), k, l, q_words + 2); - if (!BN_add(kq, kq, dsa->q)) - goto err; - if (BN_num_bits(kq) <= BN_num_bits(dsa->q)) { - if (!BN_add(kq, kq, dsa->q)) + if ((dsa)->meth->bn_mod_exp != NULL) { + if (!dsa->meth->bn_mod_exp(dsa, r, dsa->g, k, dsa->p, ctx, + dsa->method_mont_p)) goto err; - } - - K = kq; } else { - K = k; + if (!BN_mod_exp_mont(r, dsa->g, k, dsa->p, ctx, dsa->method_mont_p)) + goto err; } - DSA_BN_MOD_EXP(goto err, dsa, r, dsa->g, K, dsa->p, ctx, - dsa->method_mont_p); + if (!BN_mod(r, r, dsa->q, ctx)) goto err; - /* Compute part of 's = inv(k) (m + xr) mod q' */ - if ((kinv = BN_mod_inverse(NULL, k, dsa->q, ctx)) == NULL) + /* Compute part of 's = inv(k) (m + xr) mod q' */ + if ((kinv = dsa_mod_inverse_fermat(k, dsa->q, ctx)) == NULL) goto err; - if (*kinvp != NULL) - BN_clear_free(*kinvp); + BN_clear_free(*kinvp); *kinvp = kinv; kinv = NULL; - if (*rp != NULL) - BN_clear_free(*rp); - *rp = r; ret = 1; err: - if (!ret) { + if (!ret) DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB); - if (r != NULL) - BN_clear_free(r); - } - if (ctx_in == NULL) + if (ctx != ctx_in) BN_CTX_free(ctx); BN_clear_free(k); - BN_clear_free(kq); - return (ret); + BN_clear_free(l); + return ret; } static int dsa_do_verify(const unsigned char *dgst, int dgst_len, @@ -340,6 +294,7 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, BN_CTX *ctx; BIGNUM *u1, *u2, *t1; BN_MONT_CTX *mont = NULL; + const BIGNUM *r, *s; int ret = -1, i; if (!dsa->p || !dsa->q || !dsa->g) { DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MISSING_PARAMETERS); @@ -361,16 +316,18 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, u2 = BN_new(); t1 = BN_new(); ctx = BN_CTX_new(); - if (!u1 || !u2 || !t1 || !ctx) + if (u1 == NULL || u2 == NULL || t1 == NULL || ctx == NULL) goto err; - if (BN_is_zero(sig->r) || BN_is_negative(sig->r) || - BN_ucmp(sig->r, dsa->q) >= 0) { + DSA_SIG_get0(sig, &r, &s); + + if (BN_is_zero(r) || BN_is_negative(r) || + BN_ucmp(r, dsa->q) >= 0) { ret = 0; goto err; } - if (BN_is_zero(sig->s) || BN_is_negative(sig->s) || - BN_ucmp(sig->s, dsa->q) >= 0) { + if (BN_is_zero(s) || BN_is_negative(s) || + BN_ucmp(s, dsa->q) >= 0) { ret = 0; goto err; } @@ -378,7 +335,7 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, /* * Calculate W = inv(S) mod Q save W in u2 */ - if ((BN_mod_inverse(u2, sig->s, dsa->q, ctx)) == NULL) + if ((BN_mod_inverse(u2, s, dsa->q, ctx)) == NULL) goto err; /* save M in u1 */ @@ -397,19 +354,26 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, goto err; /* u2 = r * w mod q */ - if (!BN_mod_mul(u2, sig->r, u2, dsa->q, ctx)) + if (!BN_mod_mul(u2, r, u2, dsa->q, ctx)) goto err; if (dsa->flags & DSA_FLAG_CACHE_MONT_P) { mont = BN_MONT_CTX_set_locked(&dsa->method_mont_p, - CRYPTO_LOCK_DSA, dsa->p, ctx); + dsa->lock, dsa->p, ctx); if (!mont) goto err; } - DSA_MOD_EXP(goto err, dsa, t1, dsa->g, u1, dsa->pub_key, u2, dsa->p, ctx, - mont); - /* BN_copy(&u1,&t1); */ + if (dsa->meth->dsa_mod_exp != NULL) { + if (!dsa->meth->dsa_mod_exp(dsa, t1, dsa->g, u1, dsa->pub_key, u2, + dsa->p, ctx, mont)) + goto err; + } else { + if (!BN_mod_exp2_mont(t1, dsa->g, u1, dsa->pub_key, u2, dsa->p, ctx, + mont)) + goto err; + } + /* let u1 = u1 mod q */ if (!BN_mod(u1, t1, dsa->q, ctx)) goto err; @@ -417,31 +381,54 @@ static int dsa_do_verify(const unsigned char *dgst, int dgst_len, /* * V is now in u1. If the signature is correct, it will be equal to R. */ - ret = (BN_ucmp(u1, sig->r) == 0); + ret = (BN_ucmp(u1, r) == 0); err: if (ret < 0) DSAerr(DSA_F_DSA_DO_VERIFY, ERR_R_BN_LIB); - if (ctx != NULL) - BN_CTX_free(ctx); - if (u1) - BN_free(u1); - if (u2) - BN_free(u2); - if (t1) - BN_free(t1); - return (ret); + BN_CTX_free(ctx); + BN_free(u1); + BN_free(u2); + BN_free(t1); + return ret; } static int dsa_init(DSA *dsa) { dsa->flags |= DSA_FLAG_CACHE_MONT_P; - return (1); + return 1; } static int dsa_finish(DSA *dsa) { - if (dsa->method_mont_p) - BN_MONT_CTX_free(dsa->method_mont_p); - return (1); + BN_MONT_CTX_free(dsa->method_mont_p); + return 1; +} + +/* + * Compute the inverse of k modulo q. + * Since q is prime, Fermat's Little Theorem applies, which reduces this to + * mod-exp operation. Both the exponent and modulus are public information + * so a mod-exp that doesn't leak the base is sufficient. A newly allocated + * BIGNUM is returned which the caller must free. + */ +static BIGNUM *dsa_mod_inverse_fermat(const BIGNUM *k, const BIGNUM *q, + BN_CTX *ctx) +{ + BIGNUM *res = NULL; + BIGNUM *r, *e; + + if ((r = BN_new()) == NULL) + return NULL; + + BN_CTX_start(ctx); + if ((e = BN_CTX_get(ctx)) != NULL + && BN_set_word(r, 2) + && BN_sub(e, q, r) + && BN_mod_exp_mont(r, k, e, q, ctx, NULL)) + res = r; + else + BN_free(r); + BN_CTX_end(ctx); + return res; }