Added encryption function for 12-round salsa20.

1 files changed, 74 insertions, 0 deletions

diff --git a/salsa20r12-crypt.c b/salsa20r12-crypt.c
new file mode 100644
index 00000000..0c82217b
--- /dev/null
+++ b/salsa20r12-crypt.c
@@ -0,0 +1,74 @@
+/* salsa20r12-crypt.c
+ *
+ * The Salsa20 stream cipher.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2013 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., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02111-1301, USA.
+ */
+
+/* Based on:
+   salsa20-ref.c version 20051118
+   D. J. Bernstein
+   Public domain.
+*/
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <string.h>
+
+#include "salsa20.h"
+
+#include "macros.h"
+#include "memxor.h"
+
+void
+salsa20r12_crypt(struct salsa20_ctx *ctx,
+	      unsigned length,
+	      uint8_t *c,
+	      const uint8_t *m)
+{
+  uint32_t x[_SALSA20_INPUT_LENGTH];
+
+  if (!length)
+    return;
+  
+  for (;;)
+    {
+
+      _salsa20_core (x, ctx->input, 12);
+
+      ctx->input[9] += (++ctx->input[8] == 0);
+
+      /* stopping at 2^70 length per nonce is user's responsibility */
+      
+      if (length <= SALSA20_BLOCK_SIZE)
+	{
+	  memxor3 (c, m, (uint8_t *) x, length);
+	  return;
+	}
+      memxor3 (c, m, (uint8_t *) x, SALSA20_BLOCK_SIZE);
+
+      length -= SALSA20_BLOCK_SIZE;
+      c += SALSA20_BLOCK_SIZE;
+      m += SALSA20_BLOCK_SIZE;
+    }
+}