diff options
Diffstat (limited to 'openssl-1.1.0h/crypto/dsa/dsa_ossl.c')
| -rw-r--r-- | openssl-1.1.0h/crypto/dsa/dsa_ossl.c | 365 |
1 files changed, 365 insertions, 0 deletions
diff --git a/openssl-1.1.0h/crypto/dsa/dsa_ossl.c b/openssl-1.1.0h/crypto/dsa/dsa_ossl.c new file mode 100644 index 0000000..7f48cf2 --- /dev/null +++ b/openssl-1.1.0h/crypto/dsa/dsa_ossl.c @@ -0,0 +1,365 @@ +/* + * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved. + * + * 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 <schoch@sheba.arc.nasa.gov> */ + +#include <stdio.h> +#include "internal/cryptlib.h" +#include <openssl/bn.h> +#include <openssl/sha.h> +#include "dsa_locl.h" +#include <openssl/asn1.h> + +static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa); +static int dsa_sign_setup_no_digest(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, + BIGNUM **rp); +static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, + BIGNUM **rp, const unsigned char *dgst, int dlen); +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_no_digest, + dsa_do_verify, + NULL, /* dsa_mod_exp, */ + NULL, /* dsa_bn_mod_exp, */ + dsa_init, + dsa_finish, + DSA_FLAG_FIPS_METHOD, + NULL, + NULL, + NULL +}; + +static const DSA_METHOD *default_DSA_method = &openssl_dsa_meth; + +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) +{ + return &openssl_dsa_meth; +} + +static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa) +{ + BIGNUM *kinv = NULL; + BIGNUM *m; + BIGNUM *xr; + BN_CTX *ctx = NULL; + int reason = ERR_R_BN_LIB; + DSA_SIG *ret = NULL; + int rv = 0; + + m = BN_new(); + xr = BN_new(); + if (m == NULL || xr == NULL) + goto err; + + if (!dsa->p || !dsa->q || !dsa->g) { + reason = DSA_R_MISSING_PARAMETERS; + goto err; + } + + 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; + redo: + if (!dsa_sign_setup(dsa, ctx, &kinv, &ret->r, dgst, dlen)) + goto err; + + 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, ret->r, dsa->q, ctx)) + goto err; /* s = xr */ + if (!BN_add(ret->s, xr, m)) + goto err; /* s = m + xr */ + if (BN_cmp(ret->s, dsa->q) > 0) + if (!BN_sub(ret->s, ret->s, dsa->q)) + goto err; + if (!BN_mod_mul(ret->s, ret->s, kinv, 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(ret->r) || BN_is_zero(ret->s)) + goto redo; + + rv = 1; + + err: + if (rv == 0) { + DSAerr(DSA_F_DSA_DO_SIGN, reason); + DSA_SIG_free(ret); + ret = NULL; + } + BN_CTX_free(ctx); + BN_clear_free(m); + BN_clear_free(xr); + BN_clear_free(kinv); + return ret; +} + +static int dsa_sign_setup_no_digest(DSA *dsa, BN_CTX *ctx_in, + BIGNUM **kinvp, BIGNUM **rp) +{ + return dsa_sign_setup(dsa, ctx_in, kinvp, rp, NULL, 0); +} + +static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, + BIGNUM **kinvp, BIGNUM **rp, + const unsigned char *dgst, int dlen) +{ + BN_CTX *ctx = NULL; + BIGNUM *k, *kinv = NULL, *r = *rp; + BIGNUM *l, *m; + int ret = 0; + int q_bits; + + if (!dsa->p || !dsa->q || !dsa->g) { + DSAerr(DSA_F_DSA_SIGN_SETUP, DSA_R_MISSING_PARAMETERS); + return 0; + } + + k = BN_new(); + l = BN_new(); + m = BN_new(); + if (k == NULL || l == NULL || m == NULL) + goto err; + + if (ctx_in == NULL) { + if ((ctx = BN_CTX_new()) == NULL) + goto err; + } else + ctx = ctx_in; + + /* 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; + + /* Get random k */ + do { + if (dgst != NULL) { + /* + * We calculate k from SHA512(private_key + H(message) + random). + * This protects the private key from a weak PRNG. + */ + if (!BN_generate_dsa_nonce(k, dsa->q, dsa->priv_key, dgst, + dlen, ctx)) + goto err; + } else if (!BN_rand_range(k, dsa->q)) + goto err; + } while (BN_is_zero(k)); + + 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, + dsa->lock, 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 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. + * + * 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(r, dsa->g, k, dsa->p, ctx, dsa->method_mont_p)) + goto err; + } + + 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; + + BN_clear_free(*kinvp); + *kinvp = kinv; + kinv = NULL; + ret = 1; + err: + if (!ret) + DSAerr(DSA_F_DSA_SIGN_SETUP, ERR_R_BN_LIB); + if (ctx != ctx_in) + 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; + 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); + 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; + } + u1 = BN_new(); + u2 = BN_new(); + t1 = BN_new(); + ctx = BN_CTX_new(); + if (u1 == NULL || u2 == NULL || t1 == NULL || ctx == NULL) + goto err; + + 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(s) || BN_is_negative(s) || + BN_ucmp(s, dsa->q) >= 0) { + ret = 0; + goto err; + } + + /* + * Calculate W = inv(S) mod Q save W in u2 + */ + if ((BN_mod_inverse(u2, 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, 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, + dsa->lock, 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; + } + + /* 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, r) == 0); + + err: + if (ret < 0) + DSAerr(DSA_F_DSA_DO_VERIFY, 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); +} |