Add PSS variants for RSA sign/verify functions

Signed-off-by: Daiki Ueno <dueno@redhat.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/rsa-pss-sha256-verify.c b/rsa-pss-sha256-verify.c
new file mode 100644
index 00000000..81bc4e68
--- /dev/null
+++ b/rsa-pss-sha256-verify.c
@@ -0,0 +1,60 @@
+/* rsa-pss-sha256-verify.c
+
+   Verifying signatures created with RSA and SHA-256, with PSS padding.
+
+   Copyright (C) 2017 Daiki Ueno
+
+   This file is part of GNU Nettle.
+
+   GNU Nettle is free software: you can redistribute it and/or
+   modify it under the terms of either:
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at your
+       option) any later version.
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at your
+       option) any later version.
+
+   or both in parallel, as here.
+
+   GNU Nettle 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
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see http://www.gnu.org/licenses/.
+*/
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "rsa.h"
+
+#include "bignum.h"
+#include "pss.h"
+
+int
+rsa_pss_sha256_verify_digest(const struct rsa_public_key *key,
+			     size_t salt_length,
+			     const uint8_t *digest,
+			     const mpz_t signature)
+{
+  int res;
+  mpz_t m;
+
+  mpz_init (m);
+
+  res = (_rsa_verify_recover(key, m, signature) &&
+	 pss_verify_mgf1(m, mpz_sizeinbase(key->n, 2) - 1, &nettle_sha256,
+			 salt_length, digest));
+
+  mpz_clear (m);
+  return res;
+}