Implemented chacha, based on contribution by Joachim Strömbergson.

1 files changed, 61 insertions, 0 deletions

diff --git a/chacha128-set-key.c b/chacha128-set-key.c
new file mode 100644
index 00000000..569e801c
--- /dev/null
+++ b/chacha128-set-key.c
@@ -0,0 +1,61 @@
+/* chacha128-set-key.c
+ *
+ * ChaCha key setup for 128-bit keys.
+ * Based on the Salsa20 implementation in Nettle.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2013 Joachim Strömbergon
+ * Copyright (C) 2012 Simon Josefsson
+ * Copyright (C) 2012, 2014 Niels Möller
+ *  
+ * 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:
+   ChaCha specification (doc id: 4027b5256e17b9796842e6d0f68b0b5e) and reference 
+   implementation dated 2008.01.20
+   D. J. Bernstein
+   Public domain.
+*/
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <assert.h>
+#include <string.h>
+
+#include "chacha.h"
+
+#include "macros.h"
+
+void
+chacha128_set_key(struct chacha_ctx *ctx, const uint8_t *key)
+{
+  static const uint32_t tau[4] = {
+    /* "expand 16-byte k" */
+    0x61707865, 0x3120646e, 0x79622d36, 0x6b206574
+  };
+
+  ctx->state[8]  = ctx->state[4] = LE_READ_UINT32(key + 0);
+  ctx->state[9]  = ctx->state[5] = LE_READ_UINT32(key + 4);
+  ctx->state[10] = ctx->state[6] = LE_READ_UINT32(key + 8);
+  ctx->state[11] = ctx->state[7] = LE_READ_UINT32(key + 12);
+
+  memcpy (ctx->state, tau, sizeof(tau));
+}