143 lines
4.7 KiB
C
143 lines
4.7 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
|
|
/* SPDX-License-Identifier: Unlicense */
|
|
#include "tomcrypt_private.h"
|
|
|
|
/**
|
|
@file dsa_sign_hash.c
|
|
DSA implementation, sign a hash, Tom St Denis
|
|
*/
|
|
|
|
#ifdef LTC_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 ltc_mp_init() first)
|
|
@param s The "s" integer of the signature (caller must initialize with ltc_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,
|
|
void *r, void *s,
|
|
prng_state *prng, int wprng, const dsa_key *key)
|
|
{
|
|
void *k, *kinv, *tmp;
|
|
unsigned char *buf;
|
|
int err, qbits;
|
|
|
|
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 >= LTC_MDSA_MAX_GROUP) {
|
|
return CRYPT_INVALID_ARG;
|
|
}
|
|
|
|
buf = XMALLOC(LTC_MDSA_MAX_GROUP);
|
|
if (buf == NULL) {
|
|
return CRYPT_MEM;
|
|
}
|
|
|
|
/* Init our temps */
|
|
if ((err = ltc_mp_init_multi(&k, &kinv, &tmp, LTC_NULL)) != CRYPT_OK) { goto ERRBUF; }
|
|
|
|
qbits = ltc_mp_count_bits(key->q);
|
|
retry:
|
|
|
|
do {
|
|
/* gen random k */
|
|
if ((err = rand_bn_bits(k, qbits, prng, wprng)) != CRYPT_OK) { goto error; }
|
|
|
|
/* k should be from range: 1 <= k <= q-1 (see FIPS 186-4 B.2.2) */
|
|
if (ltc_mp_cmp_d(k, 0) != LTC_MP_GT || ltc_mp_cmp(k, key->q) != LTC_MP_LT) { goto retry; }
|
|
|
|
/* test gcd */
|
|
if ((err = ltc_mp_gcd(k, key->q, tmp)) != CRYPT_OK) { goto error; }
|
|
} while (ltc_mp_cmp_d(tmp, 1) != LTC_MP_EQ);
|
|
|
|
/* now find 1/k mod q */
|
|
if ((err = ltc_mp_invmod(k, key->q, kinv)) != CRYPT_OK) { goto error; }
|
|
|
|
/* now find r = g^k mod p mod q */
|
|
if ((err = ltc_mp_exptmod(key->g, k, key->p, r)) != CRYPT_OK) { goto error; }
|
|
if ((err = ltc_mp_mod(r, key->q, r)) != CRYPT_OK) { goto error; }
|
|
|
|
if (ltc_mp_iszero(r) == LTC_MP_YES) { goto retry; }
|
|
|
|
/* FIPS 186-4 4.6: use leftmost min(bitlen(q), bitlen(hash)) bits of 'hash'*/
|
|
inlen = MIN(inlen, (unsigned long)(key->qord));
|
|
|
|
/* now find s = (in + xr)/k mod q */
|
|
if ((err = ltc_mp_read_unsigned_bin(tmp, in, inlen)) != CRYPT_OK) { goto error; }
|
|
if ((err = ltc_mp_mul(key->x, r, s)) != CRYPT_OK) { goto error; }
|
|
if ((err = ltc_mp_add(s, tmp, s)) != CRYPT_OK) { goto error; }
|
|
if ((err = ltc_mp_mulmod(s, kinv, key->q, s)) != CRYPT_OK) { goto error; }
|
|
|
|
if (ltc_mp_iszero(s) == LTC_MP_YES) { goto retry; }
|
|
|
|
err = CRYPT_OK;
|
|
error:
|
|
ltc_mp_deinit_multi(k, kinv, tmp, LTC_NULL);
|
|
ERRBUF:
|
|
#ifdef LTC_CLEAN_STACK
|
|
zeromem(buf, LTC_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, const dsa_key *key)
|
|
{
|
|
void *r, *s;
|
|
int err;
|
|
|
|
LTC_ARGCHK(in != NULL);
|
|
LTC_ARGCHK(out != NULL);
|
|
LTC_ARGCHK(outlen != NULL);
|
|
LTC_ARGCHK(key != NULL);
|
|
|
|
if (ltc_mp_init_multi(&r, &s, LTC_NULL) != CRYPT_OK) {
|
|
return CRYPT_MEM;
|
|
}
|
|
|
|
if ((err = dsa_sign_hash_raw(in, inlen, r, s, prng, wprng, key)) != CRYPT_OK) {
|
|
goto error;
|
|
}
|
|
|
|
err = der_encode_sequence_multi(out, outlen,
|
|
LTC_ASN1_INTEGER, 1UL, r,
|
|
LTC_ASN1_INTEGER, 1UL, s,
|
|
LTC_ASN1_EOL, 0UL, NULL);
|
|
|
|
error:
|
|
ltc_mp_deinit_multi(r, s, LTC_NULL);
|
|
return err;
|
|
}
|
|
|
|
#endif
|