diff options
Diffstat (limited to 'libtomcrypt/src/pk/ecc/ecc_sign_hash.c')
| -rw-r--r-- | libtomcrypt/src/pk/ecc/ecc_sign_hash.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/libtomcrypt/src/pk/ecc/ecc_sign_hash.c b/libtomcrypt/src/pk/ecc/ecc_sign_hash.c new file mode 100644 index 0000000..44f949e --- /dev/null +++ b/libtomcrypt/src/pk/ecc/ecc_sign_hash.c @@ -0,0 +1,114 @@ +/* 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, tomstdenis@gmail.com, 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 $ */ + |