--- /dev/null
+/* 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<pbytes; i++) {
+ buf[i] = ch;
+ ch = (in[i] << (8-shift_right));
+ buf[i] = buf[i] ^ (in[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: $Format:%ai$ */
projects / zpackage / blobdiff