Implement PSS encoding functions

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

1 files changed, 73 insertions, 0 deletions

diff --git a/pss-mgf1.c b/pss-mgf1.c
new file mode 100644
index 00000000..67df5570
--- /dev/null
+++ b/pss-mgf1.c
@@ -0,0 +1,73 @@
+/* pss-mgf1.c
+
+   PKCS#1 mask generation function 1, used in RSA-PSS (RFC-3447).
+
+   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 "pss-mgf1.h"
+
+#include <assert.h>
+#include <string.h>
+
+#include "nettle-internal.h"
+#include "macros.h"
+
+void
+pss_mgf1(const void *seed, const struct nettle_hash *hash,
+	 size_t length, uint8_t *mask)
+{
+  TMP_DECL(h, uint8_t, NETTLE_MAX_HASH_DIGEST_SIZE);
+  TMP_DECL(state, uint8_t, NETTLE_MAX_HASH_CONTEXT_SIZE);
+  size_t i;
+  uint8_t c[4];
+
+  TMP_ALLOC(h, hash->digest_size);
+  TMP_ALLOC(state, hash->context_size);
+
+  for (i = 0;;
+       i++, mask += hash->digest_size, length -= hash->digest_size)
+    {
+      WRITE_UINT32(c, i);
+
+      memcpy(state, seed, hash->context_size);
+      hash->update(state, 4, c);
+
+      if (length <= hash->digest_size)
+	{
+	  hash->digest(state, length, mask);
+	  return;
+	}
+      hash->digest(state, hash->digest_size, mask);
+    }
+}