diff --git a/ChangeLog b/ChangeLog
index c2dac5935e98a02e99714333e1e287569a5c4d79..1ad2e53b032285bcd4a3cb5597ee8ecaaa7d3c79 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+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
diff --git a/Makefile.in b/Makefile.in
index 58f7831d9455ba050a34dcdce95ca1697ec4db1b..ba0fdb279082c972ce842ade7118e38cf75372a8 100644
--- a/Makefile.in
+++ b/Makefile.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 \
diff --git a/rsa-blind.c b/rsa-blind.c
new file mode 100644
index 0000000000000000000000000000000000000000..eb5d0088806206c41af9520298a16dfa69ded6b6
--- /dev/null
+++ b/rsa-blind.c
@@ -0,0 +1,69 @@
+/* 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);
+}
diff --git a/rsa-decrypt-tr.c b/rsa-decrypt-tr.c
index d130a0690713b80c393a644f78c00cef30e4d76e..1e21e985bf75bd46300d0f593aefa0ee94349c57 100644
--- a/rsa-decrypt-tr.c
+++ b/rsa-decrypt-tr.c
@@ -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);
diff --git a/rsa.h b/rsa.h
index 9dc7fe2bf57a5696cdf408ff068f5d07a4b60582..1b975ab8cad5f4bf2ca07f904317cf692a9b080c 100644
--- a/rsa.h
+++ b/rsa.h
@@ -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