diff options
Diffstat (limited to 'libtomcrypt/src/pk/ecc/ecc_verify_hash.c')
| -rw-r--r-- | libtomcrypt/src/pk/ecc/ecc_verify_hash.c | 113 |
1 files changed, 74 insertions, 39 deletions
diff --git a/libtomcrypt/src/pk/ecc/ecc_verify_hash.c b/libtomcrypt/src/pk/ecc/ecc_verify_hash.c index c10076b..7aa5f52 100644 --- a/libtomcrypt/src/pk/ecc/ecc_verify_hash.c +++ b/libtomcrypt/src/pk/ecc/ecc_verify_hash.c @@ -5,52 +5,27 @@ * * The library is free for all purposes without any express * guarantee it works. - * - * Tom St Denis, tomstdenis@gmail.com, http://libtom.org */ -/* 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" +#if defined(LTC_MECC) && defined(LTC_DER) + /** @file ecc_verify_hash.c ECC Crypto, Tom St Denis */ -#if defined(LTC_MECC) && defined(LTC_DER) - -/* verify - * - * w = s^-1 mod n - * u1 = xw - * u2 = rw - * X = u1*G + u2*Q - * v = X_x1 mod n - * accept if v == r - */ - -/** - Verify an ECC signature - @param sig The signature to verify - @param siglen The length of the signature (octets) - @param hash The hash (message digest) that was signed - @param hashlen The length of the hash (octets) - @param stat Result of signature, 1==valid, 0==invalid - @param key The corresponding public ECC key - @return CRYPT_OK if successful (even if the signature is not valid) -*/ -int ecc_verify_hash(const unsigned char *sig, unsigned long siglen, +static int _ecc_verify_hash(const unsigned char *sig, unsigned long siglen, const unsigned char *hash, unsigned long hashlen, - int *stat, ecc_key *key) + int *stat, ecc_key *key, int sigformat) { ecc_point *mG, *mQ; void *r, *s, *v, *w, *u1, *u2, *e, *p, *m; void *mp; int err; + unsigned long pbits, pbytes, i, shift_right; + unsigned char ch, buf[MAXBLOCKSIZE]; LTC_ARGCHK(sig != NULL); LTC_ARGCHK(hash != NULL); @@ -79,12 +54,22 @@ int ecc_verify_hash(const unsigned char *sig, unsigned long siglen, goto error; } - /* parse header */ + if (sigformat == 1) { + /* RFC7518 format */ + if ((siglen % 2) == 1) { + err = CRYPT_INVALID_PACKET; + goto error; + } + i = siglen / 2; + if ((err = mp_read_unsigned_bin(r, (unsigned char *)sig, i)) != CRYPT_OK) { goto error; } + if ((err = mp_read_unsigned_bin(s, (unsigned char *)sig+i, i)) != CRYPT_OK) { goto error; } + } + else { + /* ASN.1 format */ if ((err = der_decode_sequence_multi(sig, siglen, LTC_ASN1_INTEGER, 1UL, r, LTC_ASN1_INTEGER, 1UL, s, - LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { - goto error; + LTC_ASN1_EOL, 0UL, NULL)) != CRYPT_OK) { goto error; } } /* get the order */ @@ -99,8 +84,24 @@ int ecc_verify_hash(const unsigned char *sig, unsigned long siglen, goto error; } - /* read hash */ - if ((err = mp_read_unsigned_bin(e, (unsigned char *)hash, (int)hashlen)) != CRYPT_OK) { goto error; } + /* read hash - truncate if needed */ + pbits = mp_count_bits(p); + pbytes = (pbits+7) >> 3; + if (pbits > hashlen*8) { + if ((err = mp_read_unsigned_bin(e, (unsigned char *)hash, hashlen)) != CRYPT_OK) { goto error; } + } + else if (pbits % 8 == 0) { + if ((err = mp_read_unsigned_bin(e, (unsigned char *)hash, pbytes)) != CRYPT_OK) { goto error; } + } + else { + shift_right = 8 - pbits % 8; + for (i=0, ch=0; i<pbytes; i++) { + buf[i] = ch; + ch = (hash[i] << (8-shift_right)); + buf[i] = buf[i] ^ (hash[i] >> shift_right); + } + if ((err = mp_read_unsigned_bin(e, (unsigned char *)buf, pbytes)) != CRYPT_OK) { goto error; } + } /* w = s^-1 mod n */ if ((err = mp_invmod(s, p, w)) != CRYPT_OK) { goto error; } @@ -158,8 +159,42 @@ error: return err; } +/** + Verify an ECC signature + @param sig The signature to verify + @param siglen The length of the signature (octets) + @param hash The hash (message digest) that was signed + @param hashlen The length of the hash (octets) + @param stat Result of signature, 1==valid, 0==invalid + @param key The corresponding public ECC key + @return CRYPT_OK if successful (even if the signature is not valid) +*/ +int ecc_verify_hash(const unsigned char *sig, unsigned long siglen, + const unsigned char *hash, unsigned long hashlen, + int *stat, ecc_key *key) +{ + return _ecc_verify_hash(sig, siglen, hash, hashlen, stat, key, 0); +} + +/** + Verify an ECC signature in RFC7518 format + @param sig The signature to verify + @param siglen The length of the signature (octets) + @param hash The hash (message digest) that was signed + @param hashlen The length of the hash (octets) + @param stat Result of signature, 1==valid, 0==invalid + @param key The corresponding public ECC key + @return CRYPT_OK if successful (even if the signature is not valid) +*/ +int ecc_verify_hash_rfc7518(const unsigned char *sig, unsigned long siglen, + const unsigned char *hash, unsigned long hashlen, + int *stat, ecc_key *key) +{ + return _ecc_verify_hash(sig, siglen, hash, hashlen, stat, key, 1); +} + #endif -/* $Source$ */ -/* $Revision$ */ -/* $Date$ */ +/* ref: $Format:%D$ */ +/* git commit: $Format:%H$ */ +/* commit time: $Format:%ai$ */ |