pineapple-src/externals/libressl/crypto/dsa/dsa_ossl.c

426 lines
11 KiB
C
Raw Normal View History

2020-12-28 15:15:37 +00:00
/* $OpenBSD: dsa_ossl.c,v 1.42 2019/06/04 18:12:26 tb 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.]
*/
/* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
#include <stdio.h>
#include <openssl/asn1.h>
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/err.h>
#include <openssl/sha.h>
#include "bn_lcl.h"
static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
BIGNUM **rp);
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 DSA_METHOD openssl_dsa_meth = {
.name = "OpenSSL DSA method",
.dsa_do_sign = dsa_do_sign,
.dsa_sign_setup = dsa_sign_setup,
.dsa_do_verify = dsa_do_verify,
.init = dsa_init,
.finish = dsa_finish,
};
const DSA_METHOD *
DSA_OpenSSL(void)
{
return &openssl_dsa_meth;
}
static DSA_SIG *
dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
{
BIGNUM b, bm, bxr, binv, m, *kinv = NULL, *r = NULL, *s = NULL;
BN_CTX *ctx = NULL;
int reason = ERR_R_BN_LIB;
DSA_SIG *ret = NULL;
int noredo = 0;
BN_init(&b);
BN_init(&binv);
BN_init(&bm);
BN_init(&bxr);
BN_init(&m);
if (!dsa->p || !dsa->q || !dsa->g) {
reason = DSA_R_MISSING_PARAMETERS;
goto err;
}
s = BN_new();
if (s == NULL)
goto err;
ctx = BN_CTX_new();
if (ctx == NULL)
goto err;
/*
* If the digest length is greater than N (the bit length of q), the
* leftmost N bits of the digest shall be used, see FIPS 186-3, 4.2.
* In this case the digest length is given in bytes.
*/
if (dlen > BN_num_bytes(dsa->q))
dlen = BN_num_bytes(dsa->q);
if (BN_bin2bn(dgst, dlen, &m) == NULL)
goto err;
redo:
if (dsa->kinv == NULL || dsa->r == NULL) {
if (!DSA_sign_setup(dsa, ctx, &kinv, &r))
goto err;
} else {
kinv = dsa->kinv;
dsa->kinv = NULL;
r = dsa->r;
dsa->r = NULL;
noredo = 1;
}
/*
* Compute:
*
* s = inv(k)(m + xr) mod q
*
* In order to reduce the possibility of a side-channel attack, the
* following is calculated using a blinding value:
*
* s = inv(b)(bm + bxr)inv(k) mod q
*
* Where b is a random value in the range [1, q).
*/
if (!bn_rand_interval(&b, BN_value_one(), dsa->q))
goto err;
if (BN_mod_inverse_ct(&binv, &b, dsa->q, ctx) == NULL)
goto err;
if (!BN_mod_mul(&bxr, &b, dsa->priv_key, dsa->q, ctx)) /* bx */
goto err;
if (!BN_mod_mul(&bxr, &bxr, r, dsa->q, ctx)) /* bxr */
goto err;
if (!BN_mod_mul(&bm, &b, &m, dsa->q, ctx)) /* bm */
goto err;
if (!BN_mod_add(s, &bxr, &bm, dsa->q, ctx)) /* s = bm + bxr */
goto err;
if (!BN_mod_mul(s, s, kinv, dsa->q, ctx)) /* s = b(m + xr)k^-1 */
goto err;
if (!BN_mod_mul(s, s, &binv, dsa->q, ctx)) /* s = (m + xr)k^-1 */
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;
}
goto redo;
}
if ((ret = DSA_SIG_new()) == NULL) {
reason = ERR_R_MALLOC_FAILURE;
goto err;
}
ret->r = r;
ret->s = s;
err:
if (!ret) {
DSAerror(reason);
BN_free(r);
BN_free(s);
}
BN_CTX_free(ctx);
BN_clear_free(&b);
BN_clear_free(&bm);
BN_clear_free(&bxr);
BN_clear_free(&binv);
BN_clear_free(&m);
BN_clear_free(kinv);
return ret;
}
static int
dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
{
BN_CTX *ctx;
BIGNUM k, l, m, *kinv = NULL, *r = NULL;
int q_bits, ret = 0;
if (!dsa->p || !dsa->q || !dsa->g) {
DSAerror(DSA_R_MISSING_PARAMETERS);
return 0;
}
BN_init(&k);
BN_init(&l);
BN_init(&m);
if (ctx_in == NULL) {
if ((ctx = BN_CTX_new()) == NULL)
goto err;
} else
ctx = ctx_in;
if ((r = BN_new()) == NULL)
goto err;
/* Preallocate space */
q_bits = BN_num_bits(dsa->q);
if (!BN_set_bit(&k, q_bits) ||
!BN_set_bit(&l, q_bits) ||
!BN_set_bit(&m, q_bits))
goto err;
if (!bn_rand_interval(&k, BN_value_one(), dsa->q))
goto err;
BN_set_flags(&k, 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))
goto err;
}
/* Compute r = (g^k mod p) mod q */
/*
* We do not want timing information to leak the length of k,
* so we compute G^k using an equivalent exponent 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.
*
* TODO: revisit the BN_copy aiming for a memory access agnostic
* conditional copy.
*/
if (!BN_add(&l, &k, dsa->q) ||
!BN_add(&m, &l, dsa->q) ||
!BN_copy(&k, BN_num_bits(&l) > q_bits ? &l : &m))
goto err;
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;
} else {
if (!BN_mod_exp_mont_ct(r, dsa->g, &k, dsa->p, ctx,
dsa->method_mont_p))
goto err;
}
if (!BN_mod_ct(r, r, dsa->q, ctx))
goto err;
/* Compute part of 's = inv(k) (m + xr) mod q' */
if ((kinv = BN_mod_inverse_ct(NULL, &k, dsa->q, ctx)) == NULL)
goto err;
BN_clear_free(*kinvp);
*kinvp = kinv;
kinv = NULL;
BN_clear_free(*rp);
*rp = r;
ret = 1;
err:
if (!ret) {
DSAerror(ERR_R_BN_LIB);
BN_clear_free(r);
}
if (ctx_in == NULL)
BN_CTX_free(ctx);
BN_clear_free(&k);
BN_clear_free(&l);
BN_clear_free(&m);
return ret;
}
static int
dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig, DSA *dsa)
{
BN_CTX *ctx;
BIGNUM u1, u2, t1;
BN_MONT_CTX *mont = NULL;
int ret = -1, i;
if (!dsa->p || !dsa->q || !dsa->g) {
DSAerror(DSA_R_MISSING_PARAMETERS);
return -1;
}
i = BN_num_bits(dsa->q);
/* FIPS 186-3 allows only three different sizes for q. */
if (i != 160 && i != 224 && i != 256) {
DSAerror(DSA_R_BAD_Q_VALUE);
return -1;
}
if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) {
DSAerror(DSA_R_MODULUS_TOO_LARGE);
return -1;
}
BN_init(&u1);
BN_init(&u2);
BN_init(&t1);
if ((ctx = BN_CTX_new()) == NULL)
goto err;
if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
BN_ucmp(sig->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) {
ret = 0;
goto err;
}
/* Calculate w = inv(s) mod q, saving w in u2. */
if ((BN_mod_inverse_ct(&u2, sig->s, dsa->q, ctx)) == NULL)
goto err;
/*
* If the digest length is greater than the size of q use the
* BN_num_bits(dsa->q) leftmost bits of the digest, see FIPS 186-3, 4.2.
*/
if (dgst_len > (i >> 3))
dgst_len = (i >> 3);
/* Save m in u1. */
if (BN_bin2bn(dgst, dgst_len, &u1) == NULL)
goto err;
/* u1 = m * w mod q */
if (!BN_mod_mul(&u1, &u1, &u2, dsa->q, ctx))
goto err;
/* u2 = r * w mod q */
if (!BN_mod_mul(&u2, sig->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);
if (!mont)
goto err;
}
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;
}
/* BN_copy(&u1,&t1); */
/* let u1 = u1 mod q */
if (!BN_mod_ct(&u1, &t1, dsa->q, ctx))
goto err;
/* v is in u1 - if the signature is correct, it will be equal to r. */
ret = BN_ucmp(&u1, sig->r) == 0;
err:
if (ret < 0)
DSAerror(ERR_R_BN_LIB);
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;
}
static int
dsa_finish(DSA *dsa)
{
BN_MONT_CTX_free(dsa->method_mont_p);
return 1;
}