249 lines
9.2 KiB
C
249 lines
9.2 KiB
C
/*
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* dlls/rsaenh/rsa.c
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* RSA public key cryptographic functions
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*
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* Copyright 2004 Michael Jung
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* Based on public domain code by Tom St Denis (tomstdenis@iahu.ca)
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
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*/
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/*
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* This file contains code from the LibTomCrypt cryptographic
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* library written by Tom St Denis (tomstdenis@iahu.ca). LibTomCrypt
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* is in the public domain. The code in this file is tailored to
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* special requirements. Take a look at http://libtomcrypt.org for the
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* original version.
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*/
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#include "tomcrypt.h"
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static const struct {
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int mpi_code, ltc_code;
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} mpi_to_ltc_codes[] = {
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{ MP_OKAY , CRYPT_OK},
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{ MP_MEM , CRYPT_MEM},
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{ MP_VAL , CRYPT_INVALID_ARG},
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};
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/* convert a MPI error to a LTC error (Possibly the most powerful function ever! Oh wait... no) */
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static int mpi_to_ltc_error(int err)
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{
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int x;
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for (x = 0; x < (int)(sizeof(mpi_to_ltc_codes)/sizeof(mpi_to_ltc_codes[0])); x++) {
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if (err == mpi_to_ltc_codes[x].mpi_code) {
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return mpi_to_ltc_codes[x].ltc_code;
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}
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}
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return CRYPT_ERROR;
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}
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extern int gen_rand_impl(unsigned char *dst, unsigned int len);
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static int rand_prime_helper(unsigned char *dst, int len, void *dat)
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{
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return gen_rand_impl(dst, len) ? len : 0;
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}
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static int rand_prime(mp_int *N, long len)
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{
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int type;
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/* get type */
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if (len < 0) {
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type = LTM_PRIME_BBS;
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len = -len;
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} else {
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/* This seems to be what MS CSP's do: */
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type = LTM_PRIME_2MSB_ON;
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/* Original LibTomCrypt: type = 0; */
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}
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/* allow sizes between 2 and 256 bytes for a prime size */
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if (len < 16 || len > 8192) {
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printf("Invalid prime size!\n");
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return CRYPT_INVALID_PRIME_SIZE;
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}
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/* New prime generation makes the code even more cryptoish-insane. Do you know what this means!!!
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-- Gir: Yeah, oh wait, er, no.
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*/
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return mpi_to_ltc_error(mp_prime_random_ex(N, mp_prime_rabin_miller_trials(len), len, type, rand_prime_helper, NULL));
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}
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int rsa_make_key(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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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 = 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)) != 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)) != 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->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_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->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;
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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->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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void rsa_free(rsa_key *key)
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{
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mp_clear_multi(&key->e, &key->d, &key->N, &key->dQ, &key->dP,
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&key->qP, &key->p, &key->q, NULL);
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}
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/* compute an RSA modular exponentiation */
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int rsa_exptmod(const unsigned char *in, unsigned long inlen,
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unsigned char *out, unsigned long *outlen, int which,
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rsa_key *key)
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{
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mp_int tmp, tmpa, tmpb;
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unsigned long x;
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int err;
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/* is the key of the right type for the operation? */
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if (which == PK_PRIVATE && (key->type != PK_PRIVATE)) {
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return CRYPT_PK_NOT_PRIVATE;
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}
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/* must be a private or public operation */
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if (which != PK_PRIVATE && which != PK_PUBLIC) {
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return CRYPT_PK_INVALID_TYPE;
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}
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/* init and copy into tmp */
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if ((err = mp_init_multi(&tmp, &tmpa, &tmpb, NULL)) != MP_OKAY) { return mpi_to_ltc_error(err); }
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if ((err = mp_read_unsigned_bin(&tmp, in, (int)inlen)) != MP_OKAY) { goto error; }
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/* sanity check on the input */
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if (mp_cmp(&key->N, &tmp) == MP_LT) {
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err = CRYPT_PK_INVALID_SIZE;
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goto done;
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}
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/* are we using the private exponent and is the key optimized? */
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if (which == PK_PRIVATE) {
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/* tmpa = tmp^dP mod p */
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if ((err = mpi_to_ltc_error(mp_exptmod(&tmp, &key->dP, &key->p, &tmpa))) != MP_OKAY) { goto error; }
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/* tmpb = tmp^dQ mod q */
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if ((err = mpi_to_ltc_error(mp_exptmod(&tmp, &key->dQ, &key->q, &tmpb))) != MP_OKAY) { goto error; }
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/* tmp = (tmpa - tmpb) * qInv (mod p) */
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if ((err = mp_sub(&tmpa, &tmpb, &tmp)) != MP_OKAY) { goto error; }
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if ((err = mp_mulmod(&tmp, &key->qP, &key->p, &tmp)) != MP_OKAY) { goto error; }
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/* tmp = tmpb + q * tmp */
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if ((err = mp_mul(&tmp, &key->q, &tmp)) != MP_OKAY) { goto error; }
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if ((err = mp_add(&tmp, &tmpb, &tmp)) != MP_OKAY) { goto error; }
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} else {
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/* exptmod it */
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if ((err = mp_exptmod(&tmp, &key->e, &key->N, &tmp)) != MP_OKAY) { goto error; }
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}
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/* read it back */
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x = (unsigned long)mp_unsigned_bin_size(&key->N);
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if (x > *outlen) {
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err = CRYPT_BUFFER_OVERFLOW;
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goto done;
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}
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*outlen = x;
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/* convert it */
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memset(out, 0, x);
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if ((err = mp_to_unsigned_bin(&tmp, out+(x-mp_unsigned_bin_size(&tmp)))) != MP_OKAY) { goto error; }
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/* clean up and return */
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err = CRYPT_OK;
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goto done;
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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(&tmp, &tmpa, &tmpb, NULL);
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return err;
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}
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