Mercurial > dropbear
view libtomcrypt/src/pk/dsa/dsa_sign_hash.c @ 397:2908122e9eed channel-fix
disapproval of revision '1250b8af44b62d8f4fe0f8d9fc7e7a1cc34e7e1c'
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 03 Feb 2007 08:10:09 +0000 |
parents | 1b9e69c058d2 |
children | 0cbe8f6dbf9e |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, [email protected], http://libtomcrypt.org */ #include "tomcrypt.h" /** @file dsa_sign_hash.c DSA implementation, sign a hash, Tom St Denis */ #ifdef MDSA /** Sign a hash with DSA @param in The hash to sign @param inlen The length of the hash to sign @param r The "r" integer of the signature (caller must initialize with mp_init() first) @param s The "s" integer of the signature (caller must initialize with mp_init() first) @param prng An active PRNG state @param wprng The index of the PRNG desired @param key A private DSA key @return CRYPT_OK if successful */ int dsa_sign_hash_raw(const unsigned char *in, unsigned long inlen, mp_int *r, mp_int *s, prng_state *prng, int wprng, dsa_key *key) { mp_int k, kinv, tmp; unsigned char *buf; int err; LTC_ARGCHK(in != NULL); LTC_ARGCHK(r != NULL); LTC_ARGCHK(s != NULL); LTC_ARGCHK(key != NULL); if ((err = prng_is_valid(wprng)) != CRYPT_OK) { return err; } if (key->type != PK_PRIVATE) { return CRYPT_PK_NOT_PRIVATE; } /* check group order size */ if (key->qord >= MDSA_MAX_GROUP) { return CRYPT_INVALID_ARG; } buf = XMALLOC(MDSA_MAX_GROUP); if (buf == NULL) { return CRYPT_MEM; } /* Init our temps */ if ((err = mp_init_multi(&k, &kinv, &tmp, NULL)) != MP_OKAY) { goto error; } retry: do { /* gen random k */ if (prng_descriptor[wprng].read(buf, key->qord, prng) != (unsigned long)key->qord) { err = CRYPT_ERROR_READPRNG; goto LBL_ERR; } /* read k */ if ((err = mp_read_unsigned_bin(&k, buf, key->qord)) != MP_OKAY) { goto error; } /* k > 1 ? */ if (mp_cmp_d(&k, 1) != MP_GT) { goto retry; } /* test gcd */ if ((err = mp_gcd(&k, &key->q, &tmp)) != MP_OKAY) { goto error; } } while (mp_cmp_d(&tmp, 1) != MP_EQ); /* now find 1/k mod q */ if ((err = mp_invmod(&k, &key->q, &kinv)) != MP_OKAY) { goto error; } /* now find r = g^k mod p mod q */ if ((err = mp_exptmod(&key->g, &k, &key->p, r)) != MP_OKAY) { goto error; } if ((err = mp_mod(r, &key->q, r)) != MP_OKAY) { goto error; } if (mp_iszero(r) == MP_YES) { goto retry; } /* now find s = (in + xr)/k mod q */ if ((err = mp_read_unsigned_bin(&tmp, (unsigned char *)in, inlen)) != MP_OKAY) { goto error; } if ((err = mp_mul(&key->x, r, s)) != MP_OKAY) { goto error; } if ((err = mp_add(s, &tmp, s)) != MP_OKAY) { goto error; } if ((err = mp_mulmod(s, &kinv, &key->q, s)) != MP_OKAY) { goto error; } if (mp_iszero(s) == MP_YES) { goto retry; } err = CRYPT_OK; goto LBL_ERR; error: err = mpi_to_ltc_error(err); LBL_ERR: mp_clear_multi(&k, &kinv, &tmp, NULL); #ifdef LTC_CLEAN_STACK zeromem(buf, MDSA_MAX_GROUP); #endif XFREE(buf); return err; } /** Sign a hash with DSA @param in The hash to sign @param inlen The length of the hash to sign @param out [out] Where to store the signature @param outlen [in/out] The max size and resulting size of the signature @param prng An active PRNG state @param wprng The index of the PRNG desired @param key A private DSA key @return CRYPT_OK if successful */ int dsa_sign_hash(const unsigned char *in, unsigned long inlen, unsigned char *out, unsigned long *outlen, prng_state *prng, int wprng, dsa_key *key) { mp_int r, s; int err; LTC_ARGCHK(in != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); LTC_ARGCHK(key != NULL); if (mp_init_multi(&r, &s, NULL) != MP_OKAY) { return CRYPT_MEM; } if ((err = dsa_sign_hash_raw(in, inlen, &r, &s, prng, wprng, key)) != CRYPT_OK) { goto LBL_ERR; } err = der_encode_sequence_multi(out, outlen, LTC_ASN1_INTEGER, 1UL, &r, LTC_ASN1_INTEGER, 1UL, &s, LTC_ASN1_EOL, 0UL, NULL); LBL_ERR: mp_clear_multi(&r, &s, NULL); return err; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/pk/dsa/dsa_sign_hash.c,v $ */ /* $Revision: 1.6 $ */ /* $Date: 2005/05/15 21:48:59 $ */