--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/modes/lrw/lrw_process.c	Thu Jan 11 02:41:05 2007 +0000
@@ -0,0 +1,120 @@
+/* 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 lrw_process.c
+   LRW_MODE implementation, Encrypt/decrypt blocks, Tom St Denis
+*/
+
+#ifdef LTC_LRW_MODE
+
+/**
+  Process blocks with LRW, since decrypt/encrypt are largely the same they share this code.
+  @param pt        The "input" data
+  @param ct        [out] The "output" data
+  @param len       The length of the input, must be a multiple of 128-bits (16 octets)
+  @param mode      LRW_ENCRYPT or LRW_DECRYPT
+  @param lrw       The LRW state
+  @return  CRYPT_OK if successful
+*/
+int lrw_process(const unsigned char *pt, unsigned char *ct, unsigned long len, int mode, symmetric_LRW *lrw)
+{
+   unsigned char prod[16];
+   int           x, err;
+#ifdef LRW_TABLES
+   int           y;
+#endif
+
+   LTC_ARGCHK(pt  != NULL);
+   LTC_ARGCHK(ct  != NULL);
+   LTC_ARGCHK(lrw != NULL);
+
+   if (len & 15) {
+      return CRYPT_INVALID_ARG;
+   }
+
+   while (len) {
+      /* copy pad */
+      XMEMCPY(prod, lrw->pad, 16);
+
+      /* increment IV */
+      for (x = 15; x >= 0; x--) {
+          lrw->IV[x] = (lrw->IV[x] + 1) & 255;
+          if (lrw->IV[x]) { 
+              break;
+          }
+      }
+
+      /* update pad */
+#ifdef LRW_TABLES
+      /* for each byte changed we undo it's affect on the pad then add the new product */
+      for (; x < 16; x++) {
+#ifdef LTC_FAST
+          for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
+              *((LTC_FAST_TYPE *)(lrw->pad + y)) ^= *((LTC_FAST_TYPE *)(&lrw->PC[x][lrw->IV[x]][y])) ^ *((LTC_FAST_TYPE *)(&lrw->PC[x][(lrw->IV[x]-1)&255][y]));
+          }
+#else
+          for (y = 0; y < 16; y++) {
+              lrw->pad[y] ^= lrw->PC[x][lrw->IV[x]][y] ^ lrw->PC[x][(lrw->IV[x]-1)&255][y];
+          }
+#endif
+      }
+#else
+      gcm_gf_mult(lrw->tweak, lrw->IV, lrw->pad);
+#endif
+
+      /* xor prod */
+#ifdef LTC_FAST
+      for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
+           *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(pt + x)) ^ *((LTC_FAST_TYPE *)(prod + x));
+      }
+#else
+      for (x = 0; x < 16; x++) {
+         ct[x] = pt[x] ^ prod[x];
+      }
+#endif
+
+      /* send through cipher */
+      if (mode == LRW_ENCRYPT) {
+         if ((err = cipher_descriptor[lrw->cipher].ecb_encrypt(ct, ct, &lrw->key)) != CRYPT_OK) {
+            return err;
+         }
+      } else {
+         if ((err = cipher_descriptor[lrw->cipher].ecb_decrypt(ct, ct, &lrw->key)) != CRYPT_OK) {
+            return err;
+         }
+      }               
+
+      /* xor prod */
+#ifdef LTC_FAST
+      for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
+           *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(ct + x)) ^ *((LTC_FAST_TYPE *)(prod + x));
+      }
+#else
+      for (x = 0; x < 16; x++) {
+         ct[x] = ct[x] ^ prod[x];
+      }
+#endif
+   
+      /* move to next */
+      pt  += 16;
+      ct  += 16;
+      len -= 16;
+   }
+
+   return CRYPT_OK;
+}
+      
+#endif
+/* $Source: /cvs/libtom/libtomcrypt/src/modes/lrw/lrw_process.c,v $ */
+/* $Revision: 1.10 $ */
+/* $Date: 2006/06/29 01:53:13 $ */