Commit a3eb7a92 authored by Niels Möller's avatar Niels Möller

Moved rsa blinding code to a separate file.

parent adad6eaa
2012-06-09 Niels Möller <nisse@lysator.liu.se>
* rsa.h (_rsa_blind, _rsa_unblind): Declare functions.
* rsa-blind.c (_rsa_blind, _rsa_unblind): Functions moved to a
separate file, renamed and made non-static. Moved from...
* rsa-decrypt-tr.c: ... here.
2012-06-03 Niels Möller <nisse@lysator.liu.se>
* testsuite/pkcs1-test.c (test_main): Include leading zero in
......
......@@ -108,7 +108,7 @@ hogweed_SOURCES = sexp.c sexp-format.c \
rsa-sha256-sign.c rsa-sha256-verify.c \
rsa-sha512-sign.c rsa-sha512-verify.c \
rsa-encrypt.c rsa-decrypt.c rsa-decrypt-tr.c \
rsa-keygen.c rsa-compat.c \
rsa-keygen.c rsa-compat.c rsa-blind.c \
rsa2sexp.c sexp2rsa.c \
dsa.c dsa-sign.c dsa-verify.c dsa-keygen.c \
dsa-sha1-sign.c dsa-sha1-verify.c \
......
/* rsa-blind.c
*
* RSA blinding. It is used for timing resistant decryption or signing.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001, 2012 Niels Möller, Nikos Mavrogiannopoulos
*
* 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 "rsa.h"
#include "bignum.h"
/* Blinds the c, by computing c *= r^e (mod n), for a random r. Also
returns the inverse (ri), for use by rsa_unblind. */
void
_rsa_blind (const struct rsa_public_key *pub,
void *random_ctx, nettle_random_func random,
mpz_t c, mpz_t ri)
{
mpz_t r;
mpz_init(r);
/* c = c*(r^e)
* ri = r^(-1)
*/
do
{
nettle_mpz_random(r, random_ctx, random, pub->n);
/* invert r */
}
while (!mpz_invert (ri, r, pub->n));
/* c = c*(r^e) mod n */
mpz_powm(r, r, pub->e, pub->n);
mpz_mul(c, c, r);
mpz_fdiv_r(c, c, pub->n);
mpz_clear(r);
}
/* c *= ri mod n */
void
_rsa_unblind (const struct rsa_public_key *pub, mpz_t c, const mpz_t ri)
{
mpz_mul(c, c, ri);
mpz_fdiv_r(c, c, pub->n);
}
......@@ -33,47 +33,10 @@
#include "bignum.h"
#include "pkcs1.h"
/* Blinds the c, by computing c *= r^e (mod n), for a random r. Also
returns the inverse (ri), for use by rsa_unblind. */
static void
rsa_blind (const struct rsa_public_key *pub,
void *random_ctx, nettle_random_func random,
mpz_t c, mpz_t ri)
{
mpz_t r;
mpz_init(r);
/* c = c*(r^e)
* ri = r^(-1)
*/
do
{
nettle_mpz_random(r, random_ctx, random, pub->n);
/* invert r */
}
while (!mpz_invert (ri, r, pub->n));
/* c = c*(r^e) mod n */
mpz_powm(r, r, pub->e, pub->n);
mpz_mul(c, c, r);
mpz_fdiv_r(c, c, pub->n);
mpz_clear(r);
}
/* c *= ri mod n */
static void
rsa_unblind (const struct rsa_public_key *pub, mpz_t c, const mpz_t ri)
{
mpz_mul(c, c, ri);
mpz_fdiv_r(c, c, pub->n);
}
int
rsa_decrypt_tr(const struct rsa_public_key *pub,
const struct rsa_private_key *key,
void *random_ctx, nettle_random_func random,
void *random_ctx, nettle_random_func random,
unsigned *length, uint8_t *message,
const mpz_t gibberish)
{
......@@ -83,9 +46,9 @@ rsa_decrypt_tr(const struct rsa_public_key *pub,
mpz_init_set(m, gibberish);
mpz_init (ri);
rsa_blind (pub, random_ctx, random, m, ri);
_rsa_blind (pub, random_ctx, random, m, ri);
rsa_compute_root(key, m, m);
rsa_unblind (pub, m, ri);
_rsa_unblind (pub, m, ri);
mpz_clear (ri);
res = pkcs1_decrypt (key->size, m, length, message);
......
......@@ -73,6 +73,8 @@ extern "C" {
#define rsa_keypair_to_openpgp nettle_rsa_keypair_to_openpgp
#define _rsa_verify _nettle_rsa_verify
#define _rsa_check_size _nettle_rsa_check_size
#define _rsa_blind _nettle_rsa_blind
#define _rsa_unblind _nettle_rsa_unblind
/* This limit is somewhat arbitrary. Technically, the smallest modulo
which makes sense at all is 15 = 3*5, phi(15) = 8, size 4 bits. But
......@@ -383,6 +385,13 @@ _rsa_verify(const struct rsa_public_key *key,
unsigned
_rsa_check_size(mpz_t n);
void
_rsa_blind (const struct rsa_public_key *pub,
void *random_ctx, nettle_random_func random,
mpz_t c, mpz_t ri);
void
_rsa_unblind (const struct rsa_public_key *pub, mpz_t c, const mpz_t ri);
#ifdef __cplusplus
}
#endif
......
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