Mercurial > dropbear
view src/pk/ecc/ecc_sign_hash.c @ 380:d5faf4814ddb libtomcrypt-orig libtomcrypt-1.16
Update to LibTomCrypt 1.16
author | Matt Johnston <matt@ucc.asn.au> |
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date | Thu, 11 Jan 2007 02:22:00 +0000 |
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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.com */ /* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b * * All curves taken from NIST recommendation paper of July 1999 * Available at http://csrc.nist.gov/cryptval/dss.htm */ #include "tomcrypt.h" /** @file ecc_sign_hash.c ECC Crypto, Tom St Denis */ #ifdef MECC /** Sign a message digest @param in The message digest to sign @param inlen The length of the digest @param out [out] The destination for 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 you wish to use @param key A private ECC key @return CRYPT_OK if successful */ int ecc_sign_hash(const unsigned char *in, unsigned long inlen, unsigned char *out, unsigned long *outlen, prng_state *prng, int wprng, ecc_key *key) { ecc_key pubkey; void *r, *s, *e, *p; int err; LTC_ARGCHK(in != NULL); LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); LTC_ARGCHK(key != NULL); /* is this a private key? */ if (key->type != PK_PRIVATE) { return CRYPT_PK_NOT_PRIVATE; } /* is the IDX valid ? */ if (ltc_ecc_is_valid_idx(key->idx) != 1) { return CRYPT_PK_INVALID_TYPE; } if ((err = prng_is_valid(wprng)) != CRYPT_OK) { return err; } /* get the hash and load it as a bignum into 'e' */ /* init the bignums */ if ((err = mp_init_multi(&r, &s, &p, &e, NULL)) != CRYPT_OK) { return err; } if ((err = mp_read_radix(p, (char *)key->dp->order, 16)) != CRYPT_OK) { goto errnokey; } if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, (int)inlen)) != CRYPT_OK) { goto errnokey; } /* make up a key and export the public copy */ for (;;) { if ((err = ecc_make_key_ex(prng, wprng, &pubkey, key->dp)) != CRYPT_OK) { goto errnokey; } /* find r = x1 mod n */ if ((err = mp_mod(pubkey.pubkey.x, p, r)) != CRYPT_OK) { goto error; } if (mp_iszero(r) == LTC_MP_YES) { ecc_free(&pubkey); } else { /* find s = (e + xr)/k */ if ((err = mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK) { goto error; } /* k = 1/k */ if ((err = mp_mulmod(key->k, r, p, s)) != CRYPT_OK) { goto error; } /* s = xr */ if ((err = mp_add(e, s, s)) != CRYPT_OK) { goto error; } /* s = e + xr */ if ((err = mp_mod(s, p, s)) != CRYPT_OK) { goto error; } /* s = e + xr */ if ((err = mp_mulmod(s, pubkey.k, p, s)) != CRYPT_OK) { goto error; } /* s = (e + xr)/k */ ecc_free(&pubkey); if (mp_iszero(s) == LTC_MP_NO) { break; } } } /* store as SEQUENCE { r, s -- integer } */ err = der_encode_sequence_multi(out, outlen, LTC_ASN1_INTEGER, 1UL, r, LTC_ASN1_INTEGER, 1UL, s, LTC_ASN1_EOL, 0UL, NULL); goto errnokey; error: ecc_free(&pubkey); errnokey: mp_clear_multi(r, s, p, e, NULL); return err; } #endif /* $Source: /cvs/libtom/libtomcrypt/src/pk/ecc/ecc_sign_hash.c,v $ */ /* $Revision: 1.9 $ */ /* $Date: 2006/12/04 02:50:11 $ */