--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/modes/f8/f8_start.c	Thu Jan 11 02:41:05 2007 +0000
@@ -0,0 +1,98 @@
+/* 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.
+ *
+ * Tom St Denis, [email protected], http://libtomcrypt.com
+ */
+#include "tomcrypt.h"
+
+/**
+   @file f8_start.c
+   F8 implementation, start chain, Tom St Denis
+*/
+
+
+#ifdef LTC_F8_MODE
+
+/**
+   Initialize an F8 context
+   @param cipher      The index of the cipher desired
+   @param IV          The initial vector
+   @param key         The secret key 
+   @param keylen      The length of the secret key (octets)
+   @param salt_key    The salting key for the IV
+   @param skeylen     The length of the salting key (octets)
+   @param num_rounds  Number of rounds in the cipher desired (0 for default)
+   @param f8          The F8 state to initialize
+   @return CRYPT_OK if successful
+*/
+int f8_start(                int  cipher, const unsigned char *IV, 
+             const unsigned char *key,                    int  keylen, 
+             const unsigned char *salt_key,               int  skeylen,
+                             int  num_rounds,   symmetric_F8  *f8)
+{
+   int           x, err;
+   unsigned char tkey[MAXBLOCKSIZE];
+
+   LTC_ARGCHK(IV       != NULL);
+   LTC_ARGCHK(key      != NULL);
+   LTC_ARGCHK(salt_key != NULL);
+   LTC_ARGCHK(f8       != NULL);
+
+   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
+      return err;
+   }
+
+#ifdef LTC_FAST
+   if (cipher_descriptor[cipher].block_length % sizeof(LTC_FAST_TYPE)) {
+      return CRYPT_INVALID_ARG;
+   }
+#endif
+
+   /* copy details */
+   f8->blockcnt = 0;
+   f8->cipher   = cipher;
+   f8->blocklen = cipher_descriptor[cipher].block_length;
+   f8->padlen   = f8->blocklen;
+   
+   /* now get key ^ salt_key [extend salt_ket with 0x55 as required to match length] */
+   zeromem(tkey, sizeof(tkey));
+   for (x = 0; x < keylen && x < (int)sizeof(tkey); x++) {
+       tkey[x] = key[x];
+   }
+   for (x = 0; x < skeylen && x < (int)sizeof(tkey); x++) {
+       tkey[x] ^= salt_key[x];
+   }       
+   for (; x < keylen && x < (int)sizeof(tkey); x++) {
+       tkey[x] ^= 0x55;
+   }
+   
+   /* now encrypt with tkey[0..keylen-1] the IV and use that as the IV */
+   if ((err = cipher_descriptor[cipher].setup(tkey, keylen, num_rounds, &f8->key)) != CRYPT_OK) {
+      return err;
+   }
+   
+   /* encrypt IV */
+   if ((err = cipher_descriptor[f8->cipher].ecb_encrypt(IV, f8->MIV, &f8->key)) != CRYPT_OK) {
+      cipher_descriptor[f8->cipher].done(&f8->key);
+      return err;
+   }
+   zeromem(tkey, sizeof(tkey));
+   zeromem(f8->IV, sizeof(f8->IV));
+   
+   /* terminate this cipher */
+   cipher_descriptor[f8->cipher].done(&f8->key);
+   
+   /* init the cipher */
+   return cipher_descriptor[cipher].setup(key, keylen, num_rounds, &f8->key);
+}
+
+#endif
+
+/* $Source: /cvs/libtom/libtomcrypt/src/modes/f8/f8_start.c,v $ */
+/* $Revision: 1.7 $ */
+/* $Date: 2006/11/05 01:36:43 $ */