| /* 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@gmail.com, http://libtomcrypt.com |
| */ |
| #include "tomcrypt.h" |
| |
| /** |
| @file rsa_make_key.c |
| RSA key generation, Tom St Denis |
| */ |
| |
| #ifdef MRSA |
| |
| /** |
| Create an RSA key |
| @param prng An active PRNG state |
| @param wprng The index of the PRNG desired |
| @param size The size of the modulus (key size) desired (octets) |
| @param e The "e" value (public key). e==65537 is a good choice |
| @param key [out] Destination of a newly created private key pair |
| @return CRYPT_OK if successful, upon error all allocated ram is freed |
| */ |
| int rsa_make_key(prng_state *prng, int wprng, int size, long e, rsa_key *key) |
| { |
| void *p, *q, *tmp1, *tmp2, *tmp3; |
| int err; |
| |
| LTC_ARGCHK(ltc_mp.name != NULL); |
| LTC_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)) != CRYPT_OK) { |
| return err; |
| } |
| |
| /* make primes p and q (optimization provided by Wayne Scott) */ |
| if ((err = mp_set_int(tmp3, e)) != CRYPT_OK) { goto errkey; } /* tmp3 = e */ |
| |
| /* make prime "p" */ |
| do { |
| if ((err = rand_prime( p, size/2, prng, wprng)) != CRYPT_OK) { goto errkey; } |
| if ((err = mp_sub_d( p, 1, tmp1)) != CRYPT_OK) { goto errkey; } /* tmp1 = p-1 */ |
| if ((err = mp_gcd( tmp1, tmp3, tmp2)) != CRYPT_OK) { goto errkey; } /* 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/2, prng, wprng)) != CRYPT_OK) { goto errkey; } |
| if ((err = mp_sub_d( q, 1, tmp1)) != CRYPT_OK) { goto errkey; } /* tmp1 = q-1 */ |
| if ((err = mp_gcd( tmp1, tmp3, tmp2)) != CRYPT_OK) { goto errkey; } /* 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)) != CRYPT_OK) { goto errkey; } /* tmp2 = p-1 */ |
| /* tmp1 = q-1 (previous do/while loop) */ |
| if ((err = mp_lcm( tmp1, tmp2, tmp1)) != CRYPT_OK) { goto errkey; } /* 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)) != CRYPT_OK) { |
| goto errkey; |
| } |
| |
| if ((err = mp_set_int( key->e, e)) != CRYPT_OK) { goto errkey; } /* key->e = e */ |
| if ((err = mp_invmod( key->e, tmp1, key->d)) != CRYPT_OK) { goto errkey; } /* key->d = 1/e mod lcm(p-1,q-1) */ |
| if ((err = mp_mul( p, q, key->N)) != CRYPT_OK) { goto errkey; } /* 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)) != CRYPT_OK) { goto errkey; } /* tmp1 = q-1 */ |
| if ((err = mp_sub_d( q, 1, tmp2)) != CRYPT_OK) { goto errkey; } /* tmp2 = p-1 */ |
| if ((err = mp_mod( key->d, tmp1, key->dP)) != CRYPT_OK) { goto errkey; } /* dP = d mod p-1 */ |
| if ((err = mp_mod( key->d, tmp2, key->dQ)) != CRYPT_OK) { goto errkey; } /* dQ = d mod q-1 */ |
| if ((err = mp_invmod( q, p, key->qP)) != CRYPT_OK) { goto errkey; } /* qP = 1/q mod p */ |
| |
| if ((err = mp_copy( p, key->p)) != CRYPT_OK) { goto errkey; } |
| if ((err = mp_copy( q, key->q)) != CRYPT_OK) { goto errkey; } |
| |
| /* set key type (in this case it's CRT optimized) */ |
| key->type = PK_PRIVATE; |
| |
| /* return ok and free temps */ |
| err = CRYPT_OK; |
| goto cleanup; |
| errkey: |
| mp_clear_multi(key->d, key->e, key->N, key->dQ, key->dP, key->qP, key->p, key->q, NULL); |
| cleanup: |
| mp_clear_multi(tmp3, tmp2, tmp1, p, q, NULL); |
| return err; |
| } |
| |
| #endif |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_make_key.c,v $ */ |
| /* $Revision: 1.14 $ */ |
| /* $Date: 2006/12/04 22:23:27 $ */ |