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https://github.com/Laupetin/OpenAssetTools.git
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129 lines
3.9 KiB
C
129 lines
3.9 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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/* Implements ECC over Z/pZ for curve y^2 = x^3 - 3x + b
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*
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* All curves taken from NIST recommendation paper of July 1999
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* Available at http://csrc.nist.gov/cryptval/dss.htm
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*/
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#include "tomcrypt.h"
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/**
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@file ecc_make_key.c
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ECC Crypto, Tom St Denis
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*/
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#ifdef LTC_MECC
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/**
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Make a new ECC key
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@param prng An active PRNG state
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@param wprng The index of the PRNG you wish to use
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@param keysize The keysize for the new key (in octets from 20 to 65 bytes)
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@param key [out] Destination of the newly created key
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@return CRYPT_OK if successful, upon error all allocated memory will be freed
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*/
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int ecc_make_key(prng_state *prng, int wprng, int keysize, ecc_key *key)
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{
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int x, err;
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/* find key size */
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for (x = 0; (keysize > ltc_ecc_sets[x].size) && (ltc_ecc_sets[x].size != 0); x++);
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keysize = ltc_ecc_sets[x].size;
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if (keysize > ECC_MAXSIZE || ltc_ecc_sets[x].size == 0) {
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return CRYPT_INVALID_KEYSIZE;
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}
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err = ecc_make_key_ex(prng, wprng, key, <c_ecc_sets[x]);
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key->idx = x;
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return err;
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}
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int ecc_make_key_ex(prng_state *prng, int wprng, ecc_key *key, const ltc_ecc_set_type *dp)
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{
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int err;
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ecc_point *base;
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void *prime, *order;
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unsigned char *buf;
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int keysize;
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LTC_ARGCHK(key != NULL);
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LTC_ARGCHK(ltc_mp.name != NULL);
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LTC_ARGCHK(dp != NULL);
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/* good prng? */
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if ((err = prng_is_valid(wprng)) != CRYPT_OK) {
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return err;
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}
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key->idx = -1;
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key->dp = dp;
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keysize = dp->size;
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/* allocate ram */
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base = NULL;
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buf = XMALLOC(ECC_MAXSIZE);
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if (buf == NULL) {
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return CRYPT_MEM;
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}
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/* make up random string */
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if (prng_descriptor[wprng].read(buf, (unsigned long)keysize, prng) != (unsigned long)keysize) {
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err = CRYPT_ERROR_READPRNG;
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goto ERR_BUF;
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}
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/* setup the key variables */
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if ((err = mp_init_multi(&key->pubkey.x, &key->pubkey.y, &key->pubkey.z, &key->k, &prime, &order, NULL)) != CRYPT_OK) {
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goto ERR_BUF;
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}
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base = ltc_ecc_new_point();
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if (base == NULL) {
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err = CRYPT_MEM;
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goto errkey;
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}
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/* read in the specs for this key */
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if ((err = mp_read_radix(prime, (char *)key->dp->prime, 16)) != CRYPT_OK) { goto errkey; }
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if ((err = mp_read_radix(order, (char *)key->dp->order, 16)) != CRYPT_OK) { goto errkey; }
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if ((err = mp_read_radix(base->x, (char *)key->dp->Gx, 16)) != CRYPT_OK) { goto errkey; }
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if ((err = mp_read_radix(base->y, (char *)key->dp->Gy, 16)) != CRYPT_OK) { goto errkey; }
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if ((err = mp_set(base->z, 1)) != CRYPT_OK) { goto errkey; }
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if ((err = mp_read_unsigned_bin(key->k, (unsigned char *)buf, keysize)) != CRYPT_OK) { goto errkey; }
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/* the key should be smaller than the order of base point */
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if (mp_cmp(key->k, order) != LTC_MP_LT) {
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if((err = mp_mod(key->k, order, key->k)) != CRYPT_OK) { goto errkey; }
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}
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/* make the public key */
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if ((err = ltc_mp.ecc_ptmul(key->k, base, &key->pubkey, prime, 1)) != CRYPT_OK) { goto errkey; }
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key->type = PK_PRIVATE;
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/* free up ram */
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err = CRYPT_OK;
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goto cleanup;
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errkey:
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mp_clear_multi(key->pubkey.x, key->pubkey.y, key->pubkey.z, key->k, NULL);
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cleanup:
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ltc_ecc_del_point(base);
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mp_clear_multi(prime, order, NULL);
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ERR_BUF:
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#ifdef LTC_CLEAN_STACK
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zeromem(buf, ECC_MAXSIZE);
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#endif
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XFREE(buf);
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return err;
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}
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#endif
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/* ref: HEAD -> master, tag: v1.18.2 */
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/* git commit: 7e7eb695d581782f04b24dc444cbfde86af59853 */
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/* commit time: 2018-07-01 22:49:01 +0200 */
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