X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fpk%2Fecc%2Fecc_sign_hash.c;fp=libtomcrypt%2Fsrc%2Fpk%2Fecc%2Fecc_sign_hash.c;h=5d435699ed79c08bb093f6664a6bd582ffebd881;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage 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..5d43569 --- /dev/null +++ b/libtomcrypt/src/pk/ecc/ecc_sign_hash.c @@ -0,0 +1,171 @@ +/* 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. + */ + +#include "tomcrypt.h" + +#ifdef LTC_MECC + +/** + @file ecc_sign_hash.c + ECC Crypto, Tom St Denis +*/ + +static 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, int sigformat) +{ + ecc_key pubkey; + void *r, *s, *e, *p, *b; + int err, max_iterations = LTC_PK_MAX_RETRIES; + unsigned long pbits, pbytes, i, shift_right; + unsigned char ch, buf[MAXBLOCKSIZE]; + + 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; + } + + /* init the bignums */ + if ((err = mp_init_multi(&r, &s, &p, &e, &b, NULL)) != CRYPT_OK) { + return err; + } + if ((err = mp_read_radix(p, (char *)key->dp->order, 16)) != CRYPT_OK) { goto errnokey; } + + /* get the hash and load it as a bignum into 'e' */ + pbits = mp_count_bits(p); + pbytes = (pbits+7) >> 3; + if (pbits > inlen*8) { + if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, inlen)) != CRYPT_OK) { goto errnokey; } + } + else if (pbits % 8 == 0) { + if ((err = mp_read_unsigned_bin(e, (unsigned char *)in, pbytes)) != CRYPT_OK) { goto errnokey; } + } + else { + shift_right = 8 - pbits % 8; + for (i=0, ch=0; i> shift_right); + } + if ((err = mp_read_unsigned_bin(e, (unsigned char *)buf, pbytes)) != CRYPT_OK) { goto errnokey; } + } + + /* make up a key and export the public copy */ + do { + 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 { + if ((err = rand_bn_upto(b, p, prng, wprng)) != CRYPT_OK) { goto error; } /* b = blinding value */ + /* find s = (e + xr)/k */ + if ((err = mp_mulmod(pubkey.k, b, p, pubkey.k)) != CRYPT_OK) { goto error; } /* k = kb */ + if ((err = mp_invmod(pubkey.k, p, pubkey.k)) != CRYPT_OK) { goto error; } /* k = 1/kb */ + if ((err = mp_mulmod(key->k, r, p, s)) != CRYPT_OK) { goto error; } /* s = xr */ + if ((err = mp_mulmod(pubkey.k, s, p, s)) != CRYPT_OK) { goto error; } /* s = xr/kb */ + if ((err = mp_mulmod(pubkey.k, e, p, e)) != CRYPT_OK) { goto error; } /* e = e/kb */ + if ((err = mp_add(e, s, s)) != CRYPT_OK) { goto error; } /* s = e/kb + xr/kb */ + if ((err = mp_mulmod(s, b, p, s)) != CRYPT_OK) { goto error; } /* s = b(e/kb + xr/kb) = (e + xr)/k */ + ecc_free(&pubkey); + if (mp_iszero(s) == LTC_MP_NO) { + break; + } + } + } while (--max_iterations > 0); + + if (max_iterations == 0) { + goto errnokey; + } + + if (sigformat == 1) { + /* RFC7518 format */ + if (*outlen < 2*pbytes) { err = CRYPT_MEM; goto errnokey; } + zeromem(out, 2*pbytes); + i = mp_unsigned_bin_size(r); + if ((err = mp_to_unsigned_bin(r, out + (pbytes - i))) != CRYPT_OK) { goto errnokey; } + i = mp_unsigned_bin_size(s); + if ((err = mp_to_unsigned_bin(s, out + (2*pbytes - i))) != CRYPT_OK) { goto errnokey; } + *outlen = 2*pbytes; + err = CRYPT_OK; + } + else { + /* store as ASN.1 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, b, NULL); + return err; +} + +/** + 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) +{ + return _ecc_sign_hash(in, inlen, out, outlen, prng, wprng, key, 0); +} + +/** + Sign a message digest in RFC7518 format + @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_rfc7518(const unsigned char *in, unsigned long inlen, + unsigned char *out, unsigned long *outlen, + prng_state *prng, int wprng, ecc_key *key) +{ + return _ecc_sign_hash(in, inlen, out, outlen, prng, wprng, key, 1); +} + +#endif + +/* ref: $Format:%D$ */ +/* git commit: $Format:%H$ */ +/* commit time: $Format:%ai$ */