diff options
Diffstat (limited to 'src/pk/rsa/rsa_make_key.c')
| -rw-r--r-- | src/pk/rsa/rsa_make_key.c | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/src/pk/rsa/rsa_make_key.c b/src/pk/rsa/rsa_make_key.c new file mode 100644 index 0000000..d874106 --- /dev/null +++ b/src/pk/rsa/rsa_make_key.c @@ -0,0 +1,125 @@ +/* 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.org + */ +#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) +{ + mp_int p, q, tmp1, tmp2, tmp3; + int err; + + 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)) != 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 + +/* $Source: /cvs/libtom/libtomcrypt/src/pk/rsa/rsa_make_key.c,v $ */ +/* $Revision: 1.3 $ */ +/* $Date: 2005/05/05 14:35:59 $ */ |