| /* crypto/dsa/dsa_ossl.c */ |
| /* 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 <openssl/opensslconf.h> |
| #if !defined(OPENSSL_SYS_STARBOARD) |
| #include <stdio.h> |
| #endif // !defined(OPENSSL_SYS_STARBOARD) |
| #include "cryptlib.h" |
| #include <openssl/bn.h> |
| #include <openssl/sha.h> |
| #include <openssl/dsa.h> |
| #include <openssl/rand.h> |
| #include <openssl/asn1.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 = { |
| "OpenSSL DSA method", |
| dsa_do_sign, |
| dsa_sign_setup, |
| dsa_do_verify, |
| NULL, /* dsa_mod_exp, */ |
| NULL, /* dsa_bn_mod_exp, */ |
| dsa_init, |
| dsa_finish, |
| 0, |
| NULL, |
| NULL, |
| 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); |
| */ |
| |
| #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) |
| |
| 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 *kinv = NULL, *r = NULL, *s = NULL; |
| BIGNUM m; |
| BIGNUM xr; |
| BN_CTX *ctx = NULL; |
| int reason = ERR_R_BN_LIB; |
| DSA_SIG *ret = NULL; |
| int noredo = 0; |
| |
| BN_init(&m); |
| BN_init(&xr); |
| |
| 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; |
| 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; |
| } |
| |
| if (dlen > BN_num_bytes(dsa->q)) |
| /* |
| * 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 |
| */ |
| dlen = BN_num_bytes(dsa->q); |
| 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)) |
| goto err; |
| if (!BN_mod_mul(s, s, kinv, dsa->q, ctx)) |
| goto err; |
| |
| ret = DSA_SIG_new(); |
| if (ret == NULL) |
| 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; |
| } |
| ret->r = r; |
| ret->s = s; |
| |
| err: |
| if (!ret) { |
| DSAerr(DSA_F_DSA_DO_SIGN, reason); |
| BN_free(r); |
| BN_free(s); |
| } |
| 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); |
| } |
| |
| static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, |
| BIGNUM **rp) |
| { |
| BN_CTX *ctx; |
| BIGNUM k, kq, *K, *kinv = NULL, *r = NULL; |
| int ret = 0; |
| |
| if (!dsa->p || !dsa->q || !dsa->g) { |
| DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS); |
| return 0; |
| } |
| |
| BN_init(&k); |
| BN_init(&kq); |
| |
| if (ctx_in == NULL) { |
| if ((ctx = BN_CTX_new()) == NULL) |
| goto err; |
| } else |
| ctx = ctx_in; |
| |
| if ((r = BN_new()) == NULL) |
| goto err; |
| |
| /* Get random k */ |
| do |
| if (!BN_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); |
| } |
| |
| 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 */ |
| |
| 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 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.) |
| */ |
| |
| 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)) |
| goto err; |
| } |
| |
| K = &kq; |
| } else { |
| K = &k; |
| } |
| 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) |
| goto err; |
| |
| if (*kinvp != NULL) |
| BN_clear_free(*kinvp); |
| *kinvp = kinv; |
| kinv = NULL; |
| if (*rp != NULL) |
| BN_clear_free(*rp); |
| *rp = r; |
| ret = 1; |
| err: |
| if (!ret) { |
| DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB); |
| if (r != NULL) |
| BN_clear_free(r); |
| } |
| if (ctx_in == NULL) |
| BN_CTX_free(ctx); |
| BN_clear_free(&k); |
| BN_clear_free(&kq); |
| 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) { |
| DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_MISSING_PARAMETERS); |
| return -1; |
| } |
| |
| i = BN_num_bits(dsa->q); |
| /* fips 186-3 allows only different sizes for q */ |
| if (i != 160 && i != 224 && i != 256) { |
| DSAerr(DSA_F_DSA_DO_VERIFY, DSA_R_BAD_Q_VALUE); |
| return -1; |
| } |
| |
| if (BN_num_bits(dsa->p) > OPENSSL_DSA_MAX_MODULUS_BITS) { |
| DSAerr(DSA_F_DSA_DO_VERIFY, 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 save W in u2 |
| */ |
| if ((BN_mod_inverse(&u2, sig->s, dsa->q, ctx)) == NULL) |
| goto err; |
| |
| /* save M in u1 */ |
| if (dgst_len > (i >> 3)) |
| /* |
| * 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 |
| */ |
| dgst_len = (i >> 3); |
| 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; |
| } |
| |
| DSA_MOD_EXP(goto err, dsa, &t1, dsa->g, &u1, dsa->pub_key, &u2, dsa->p, |
| ctx, mont); |
| /* BN_copy(&u1,&t1); */ |
| /* let u1 = u1 mod q */ |
| if (!BN_mod(&u1, &t1, dsa->q, ctx)) |
| goto err; |
| |
| /* |
| * V is now in u1. If the signature is correct, it will be equal to R. |
| */ |
| ret = (BN_ucmp(&u1, sig->r) == 0); |
| |
| err: |
| /* |
| * XXX: surely this is wrong - if ret is 0, it just didn't verify; there |
| * is no error in BN. Test should be ret == -1 (Ben) |
| */ |
| if (ret != 1) |
| DSAerr(DSA_F_DSA_DO_VERIFY, ERR_R_BN_LIB); |
| if (ctx != NULL) |
| 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) |
| { |
| if (dsa->method_mont_p) |
| BN_MONT_CTX_free(dsa->method_mont_p); |
| return (1); |
| } |
