117 lines
5.1 KiB
C
117 lines
5.1 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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* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
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*/
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/* RSA Code by Tom St Denis */
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#include "mycrypt.h"
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#ifdef MRSA
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int rsa_make_key(prng_state *prng, int wprng, int size, long e, rsa_key *key)
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{
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mp_int p, q, tmp1, tmp2, tmp3;
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int err;
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_ARGCHK(key != NULL);
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if ((size < (MIN_RSA_SIZE/8)) || (size > (MAX_RSA_SIZE/8))) {
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return CRYPT_INVALID_KEYSIZE;
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}
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if ((e < 3) || ((e & 1) == 0)) {
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return CRYPT_INVALID_ARG;
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}
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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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if ((err = mp_init_multi(&p, &q, &tmp1, &tmp2, &tmp3, NULL)) != MP_OKAY) {
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return mpi_to_ltc_error(err);
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}
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/* make primes p and q (optimization provided by Wayne Scott) */
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if ((err = mp_set_int(&tmp3, e)) != MP_OKAY) { goto error; } /* tmp3 = e */
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/* make prime "p" */
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do {
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if ((err = rand_prime(&p, size*4, prng, wprng)) != CRYPT_OK) { goto done; }
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if ((err = mp_sub_d(&p, 1, &tmp1)) != MP_OKAY) { goto error; } /* tmp1 = p-1 */
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if ((err = mp_gcd(&tmp1, &tmp3, &tmp2)) != MP_OKAY) { goto error; } /* tmp2 = gcd(p-1, e) */
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} while (mp_cmp_d(&tmp2, 1) != 0); /* while e divides p-1 */
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/* make prime "q" */
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do {
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if ((err = rand_prime(&q, size*4, prng, wprng)) != CRYPT_OK) { goto done; }
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if ((err = mp_sub_d(&q, 1, &tmp1)) != MP_OKAY) { goto error; } /* tmp1 = q-1 */
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if ((err = mp_gcd(&tmp1, &tmp3, &tmp2)) != MP_OKAY) { goto error; } /* tmp2 = gcd(q-1, e) */
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} while (mp_cmp_d(&tmp2, 1) != 0); /* while e divides q-1 */
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/* tmp1 = lcm(p-1, q-1) */
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if ((err = mp_sub_d(&p, 1, &tmp2)) != MP_OKAY) { goto error; } /* tmp2 = p-1 */
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/* tmp1 = q-1 (previous do/while loop) */
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if ((err = mp_lcm(&tmp1, &tmp2, &tmp1)) != MP_OKAY) { goto error; } /* tmp1 = lcm(p-1, q-1) */
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/* make key */
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if ((err = mp_init_multi(&key->e, &key->d, &key->N, &key->dQ, &key->dP,
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&key->qP, &key->pQ, &key->p, &key->q, NULL)) != MP_OKAY) {
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goto error;
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}
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if ((err = mp_set_int(&key->e, e)) != MP_OKAY) { goto error2; } /* key->e = e */
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if ((err = mp_invmod(&key->e, &tmp1, &key->d)) != MP_OKAY) { goto error2; } /* key->d = 1/e mod lcm(p-1,q-1) */
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if ((err = mp_mul(&p, &q, &key->N)) != MP_OKAY) { goto error2; } /* key->N = pq */
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/* optimize for CRT now */
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/* find d mod q-1 and d mod p-1 */
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if ((err = mp_sub_d(&p, 1, &tmp1)) != MP_OKAY) { goto error2; } /* tmp1 = q-1 */
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if ((err = mp_sub_d(&q, 1, &tmp2)) != MP_OKAY) { goto error2; } /* tmp2 = p-1 */
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if ((err = mp_mod(&key->d, &tmp1, &key->dP)) != MP_OKAY) { goto error2; } /* dP = d mod p-1 */
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if ((err = mp_mod(&key->d, &tmp2, &key->dQ)) != MP_OKAY) { goto error2; } /* dQ = d mod q-1 */
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if ((err = mp_invmod(&q, &p, &key->qP)) != MP_OKAY) { goto error2; } /* qP = 1/q mod p */
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if ((err = mp_mulmod(&key->qP, &q, &key->N, &key->qP)) != MP_OKAY) { goto error2; } /* qP = q * (1/q mod p) mod N */
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if ((err = mp_invmod(&p, &q, &key->pQ)) != MP_OKAY) { goto error2; } /* pQ = 1/p mod q */
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if ((err = mp_mulmod(&key->pQ, &p, &key->N, &key->pQ)) != MP_OKAY) { goto error2; } /* pQ = p * (1/p mod q) mod N */
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if ((err = mp_copy(&p, &key->p)) != MP_OKAY) { goto error2; }
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if ((err = mp_copy(&q, &key->q)) != MP_OKAY) { goto error2; }
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/* shrink ram required */
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if ((err = mp_shrink(&key->e)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->d)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->N)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->dQ)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->dP)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->qP)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->pQ)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->p)) != MP_OKAY) { goto error2; }
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if ((err = mp_shrink(&key->q)) != MP_OKAY) { goto error2; }
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/* set key type (in this case it's CRT optimized) */
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key->type = PK_PRIVATE_OPTIMIZED;
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/* return ok and free temps */
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err = CRYPT_OK;
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goto done;
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error2:
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mp_clear_multi(&key->d, &key->e, &key->N, &key->dQ, &key->dP,
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&key->qP, &key->pQ, &key->p, &key->q, NULL);
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error:
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err = mpi_to_ltc_error(err);
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done:
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mp_clear_multi(&tmp3, &tmp2, &tmp1, &p, &q, NULL);
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return err;
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}
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#endif
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