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