Commit 479aafcc authored by Niels Möller's avatar Niels Möller

New function pkcs1_decrypt, use in rsa_decrypt.

parent e9045bd3
2012-04-09 Niels Möller <nisse@lysator.liu.se>
* Makefile.in (hogweed_SOURCES): Added pkcs1-decrypt.c.
* rsa-decrypt.c (rsa_decrypt): Use pkcs1_decrypt.
* pkcs1-decrypt.c (pkcs1_decrypt): New file and function,
extracted from rsa_decrypt.
2012-04-01 Niels Möller <nisse@lysator.liu.se>
* salsa20.c (LE_SWAP32): Typo fix for big-endian case.
......
......@@ -99,7 +99,7 @@ hogweed_SOURCES = sexp.c sexp-format.c \
bignum.c bignum-next-prime.c \
bignum-random.c bignum-random-prime.c \
sexp2bignum.c \
pkcs1.c pkcs1-rsa-md5.c pkcs1-rsa-sha1.c \
pkcs1.c pkcs1-decrypt.c pkcs1-rsa-md5.c pkcs1-rsa-sha1.c \
pkcs1-rsa-sha256.c pkcs1-rsa-sha512.c \
rsa.c rsa-sign.c rsa-verify.c \
rsa-md5-sign.c rsa-md5-verify.c \
......
/* pkcs1-decrypt.c
*
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001, 2012 Niels Möller
*
* 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.
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <string.h>
#include "pkcs1.h"
#include "bignum.h"
#include "nettle-internal.h"
int
pkcs1_decrypt (unsigned key_size,
const mpz_t m,
unsigned *length, uint8_t *message)
{
TMP_DECL(em, uint8_t, NETTLE_MAX_BIGNUM_BITS / 8);
uint8_t *terminator;
unsigned padding;
unsigned message_length;
TMP_ALLOC(em, key_size);
nettle_mpz_get_str_256(key_size, em, 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;
}
......@@ -43,6 +43,7 @@ extern "C" {
#define pkcs1_rsa_sha256_encode_digest nettle_pkcs1_rsa_sha256_encode_digest
#define pkcs1_rsa_sha512_encode nettle_pkcs1_rsa_sha512_encode
#define pkcs1_rsa_sha512_encode_digest nettle_pkcs1_rsa_sha512_encode_digest
#define pkcs1_decrypt nettle_pkcs1_decrypt
struct md5_ctx;
struct sha1_ctx;
......@@ -56,6 +57,11 @@ pkcs1_signature_prefix(unsigned size,
const uint8_t *id,
unsigned digest_size);
int
pkcs1_decrypt (unsigned key_size,
const mpz_t m,
unsigned *length, uint8_t *message);
int
pkcs1_rsa_md5_encode(mpz_t m, unsigned length, struct md5_ctx *hash);
......
/* rsa_decrypt.c
/* rsa-decrypt.c
*
* The RSA publickey algorithm. PKCS#1 encryption.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001 Niels Möller
* Copyright (C) 2001, 2012 Niels Möller
*
* 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
......@@ -27,54 +27,22 @@
# include "config.h"
#endif
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "rsa.h"
#include "bignum.h"
#include "nettle-internal.h"
#include "pkcs1.h"
int
rsa_decrypt(const struct rsa_private_key *key,
unsigned *length, uint8_t *message,
const mpz_t gibberish)
{
TMP_DECL(em, uint8_t, NETTLE_MAX_BIGNUM_BITS / 8);
uint8_t *terminator;
unsigned padding;
unsigned message_length;
mpz_t m;
int res;
mpz_init(m);
rsa_compute_root(key, m, gibberish);
TMP_ALLOC(em, key->size);
nettle_mpz_get_str_256(key->size, em, m);
res = pkcs1_decrypt (key->size, m, length, message);
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;
return res;
}
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