--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/encauth/ocb/ocb_decrypt_verify_memory.c	Fri May 06 13:23:02 2005 +0000
@@ -0,0 +1,82 @@
+/* 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.org
+ */
+
+/** 
+  @file ocb_decrypt_verify_memory.c
+  OCB implementation, helper to decrypt block of memory, by Tom St Denis 
+*/
+#include "tomcrypt.h"
+
+#ifdef OCB_MODE
+
+/**
+   Decrypt and compare the tag with OCB.
+   @param cipher     The index of the cipher desired
+   @param key        The secret key
+   @param keylen     The length of the secret key (octets)
+   @param nonce      The session nonce (length of the block size of the block cipher)
+   @param ct         The ciphertext
+   @param ctlen      The length of the ciphertext (octets)
+   @param pt         [out] The plaintext
+   @param tag        The tag to compare against
+   @param taglen     The length of the tag (octets)
+   @param stat       [out] The result of the tag comparison (1==valid, 0==invalid)
+   @return CRYPT_OK if successful regardless of the tag comparison
+*/
+int ocb_decrypt_verify_memory(int cipher,
+    const unsigned char *key,    unsigned long keylen,
+    const unsigned char *nonce,  
+    const unsigned char *ct,     unsigned long ctlen,
+          unsigned char *pt,
+    const unsigned char *tag,    unsigned long taglen,
+          int           *stat)
+{
+   int err;
+   ocb_state *ocb;
+
+   LTC_ARGCHK(key    != NULL);
+   LTC_ARGCHK(nonce  != NULL);
+   LTC_ARGCHK(pt     != NULL);
+   LTC_ARGCHK(ct     != NULL);
+   LTC_ARGCHK(tag    != NULL);
+   LTC_ARGCHK(stat    != NULL);
+
+   /* allocate memory */
+   ocb = XMALLOC(sizeof(ocb_state));
+   if (ocb == NULL) {
+      return CRYPT_MEM;
+   }
+
+   if ((err = ocb_init(ocb, cipher, key, keylen, nonce)) != CRYPT_OK) {
+      goto LBL_ERR; 
+   }
+
+   while (ctlen > (unsigned long)ocb->block_len) {
+        if ((err = ocb_decrypt(ocb, ct, pt)) != CRYPT_OK) {
+            goto LBL_ERR; 
+        }
+        ctlen   -= ocb->block_len;
+        pt      += ocb->block_len;
+        ct      += ocb->block_len;
+   }
+
+   err = ocb_done_decrypt(ocb, ct, ctlen, pt, tag, taglen, stat);
+LBL_ERR:
+#ifdef LTC_CLEAN_STACK
+   zeromem(ocb, sizeof(ocb_state));
+#endif
+ 
+   XFREE(ocb);
+
+   return err;
+}
+
+#endif