Commit 3a3d2d86 authored by Niels Möller's avatar Niels Möller

New files for rsa pkcs#1

encryption.

Rev: src/nettle/rsa-decrypt.c:1.1
Rev: src/nettle/rsa-encrypt.c:1.1
Rev: src/nettle/rsa.h:1.10
parent f1127d57
/* rsa_decrypt.c
*
* The RSA publickey algorithm. PKCS#1 encryption.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001 Niels Mller
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include "rsa.h"
#include "bignum.h"
#include <assert.h>
#include <stdlib.h>
#include <string.h>
int
rsa_decrypt(struct rsa_private_key *key,
unsigned *length, uint8_t *message,
const mpz_t gibberish)
{
uint8_t *em;
uint8_t *terminator;
unsigned padding;
unsigned message_length;
mpz_t m;
mpz_init(m);
rsa_compute_root(key, m, gibberish);
em = alloca(key->size);
nettle_mpz_get_str_256(key->size, em, m);
mpz_clear(m);
/* Check format */
if (em[0] || em[1] != 2)
return 0;
terminator = memchr(em + 2, 0, key->size - 2);
if (!terminator)
return 0;
padding = terminator - (em + 2);
if (padding < 8)
return 0;
message_length = key->size - 3 - padding;
if (*length < message_length)
return 0;
memcpy(message, terminator + 1, message_length);
*length = message_length;
return 1;
}
/* rsa_encrypt.c
*
* The RSA publickey algorithm. PKCS#1 encryption.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001 Niels Mller
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#include "rsa.h"
#include "bignum.h"
#include <assert.h>
#include <stdlib.h>
#include <string.h>
int
rsa_encrypt(struct rsa_public_key *key,
/* For padding */
void *random_ctx, nettle_random_func random,
unsigned length, const uint8_t *message,
mpz_t gibbberish)
{
uint8_t *em;
unsigned padding;
unsigned i;
/* The message is encoded as a string of the same length as the
* modulo n, of the form
*
* 00 02 pad 00 message
*
* where padding should be at least 8 pseudorandomly generated
* *non-zero* octets. */
if (length + 11 < key->size)
/* Message too long for this key. */
return 0;
/* At least 8 bits of random padding */
padding = key->size - length - 3;
assert(padding >= 8);
em = alloca(key->size - 1);
em[0] = 2;
random(random_ctx, padding, em + 1);
/* Replace 0-octets with 1 */
for (i = 0; i<padding; i++)
if (!em[i+1])
em[i+1] = 1;
memcpy(em + 1 + padding, message, length);
nettle_mpz_set_str_256(gibbberish, key->size - 1, em);
mpz_powm(gibbberish, gibbberish, key->e, key->n);
return 1;
}
......@@ -32,6 +32,13 @@
#include "md5.h"
#include "sha.h"
/* Randomness function. This typedef doesn't really belong here, but
* so far it's used only by rsa functions (encryption and key
* generation) */
typedef void (*nettle_random_func)(void *ctx,
unsigned length, uint8_t *dst);
/* For PKCS#1 to make sense, the size of the modulo, in octets, must
* be at least 11 + the length of the DER-encoded Digest Info.
*
......@@ -144,6 +151,31 @@ rsa_sha1_verify(struct rsa_public_key *key,
struct sha1_ctx *hash,
const mpz_t signature);
/* RSA encryption, using PKCS#1 */
/* FIXME: These functions uses the v1.5 padding. What should the v2
* (OAEP) functions be called? */
/* Returns 1 on success, 0 on failure, which happens if the
* message is too long for the key. */
int
rsa_encrypt(struct rsa_public_key *key,
/* For padding */
void *random_ctx, nettle_random_func random,
unsigned length, const uint8_t *message,
mpz_t gibbberish);
/* Message must point to a buffer of size *LENGTH. KEY->size is enough
* for all valid messages. On success, *LENGTH is updated to reflect
* the actual length of the message. Returns 1 on success, 0 on
* failure, which happens if decryption failed or if the message
* didn't fit. */
int
rsa_decrypt(struct rsa_private_key *key,
unsigned *length, uint8_t *message,
const mpz_t gibberish);
/* Compute x, the e:th root of m. Calling it with x == m is allowed. */
void
rsa_compute_root(struct rsa_private_key *key, mpz_t x, const mpz_t m);
......@@ -151,11 +183,6 @@ rsa_compute_root(struct rsa_private_key *key, mpz_t x, const mpz_t m);
/* Key generation */
/* Randomness function. This typedef doesn't really belong here, but
* so far it's used only by the rsa key generator. */
typedef void (*nettle_random_func)(void *ctx,
unsigned length, uint8_t *dst);
/* Progress report function. */
typedef void (*nettle_progress_func)(void *ctx,
int c);
......
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