1 files changed, 67 insertions, 0 deletions
diff --git a/libtomcrypt/src/stream/chacha/chacha_setup.c b/libtomcrypt/src/stream/chacha/chacha_setup.c
new file mode 100644
index 0000000..e34370b
--- /dev/null
+++ b/libtomcrypt/src/stream/chacha/chacha_setup.c
@@ -0,0 +1,67 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+
+/* The implementation is based on:
+ * chacha-ref.c version 20080118
+ * Public domain from D. J. Bernstein
+ */
+
+#include "tomcrypt.h"
+
+#ifdef LTC_CHACHA
+
+static const char * const sigma = "expand 32-byte k";
+static const char * const tau   = "expand 16-byte k";
+
+/**
+   Initialize an ChaCha context (only the key)
+   @param st        [out] The destination of the ChaCha state
+   @param key       The secret key
+   @param keylen    The length of the secret key (octets)
+   @param rounds    Number of rounds (e.g. 20 for ChaCha20)
+   @return CRYPT_OK if successful
+*/
+int chacha_setup(chacha_state *st, const unsigned char *key, unsigned long keylen, int rounds)
+{
+   const char *constants;
+
+   LTC_ARGCHK(st  != NULL);
+   LTC_ARGCHK(key != NULL);
+   LTC_ARGCHK(keylen == 32 || keylen == 16);
+
+   if (rounds == 0) rounds = 20;
+
+   LOAD32L(st->input[4], key + 0);
+   LOAD32L(st->input[5], key + 4);
+   LOAD32L(st->input[6], key + 8);
+   LOAD32L(st->input[7], key + 12);
+   if (keylen == 32) { /* 256bit */
+      key += 16;
+      constants = sigma;
+   } else { /* 128bit */
+      constants = tau;
+   }
+   LOAD32L(st->input[8],  key + 0);
+   LOAD32L(st->input[9],  key + 4);
+   LOAD32L(st->input[10], key + 8);
+   LOAD32L(st->input[11], key + 12);
+   LOAD32L(st->input[0],  constants + 0);
+   LOAD32L(st->input[1],  constants + 4);
+   LOAD32L(st->input[2],  constants + 8);
+   LOAD32L(st->input[3],  constants + 12);
+   st->rounds = rounds; /* e.g. 20 for chacha20 */
+   st->ivlen = 0; /* will be set later by chacha_ivctr(32|64) */
+   return CRYPT_OK;
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */