--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/encauth/ocb3/ocb3_decrypt_verify_memory.c	Fri Feb 09 21:44:05 2018 +0800
@@ -0,0 +1,110 @@
+/* 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.
+ */
+
+/**
+  @file ocb3_decrypt_verify_memory.c
+  OCB implementation, helper to decrypt block of memory, by Tom St Denis
+*/
+#include "tomcrypt.h"
+
+#ifdef LTC_OCB3_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 noncelen   The length of the nonce (octets)
+   @param adata      The AAD - additional associated data
+   @param adatalen   The length of AAD (octets)
+   @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 ocb3_decrypt_verify_memory(int cipher,
+    const unsigned char *key,    unsigned long keylen,
+    const unsigned char *nonce,  unsigned long noncelen,
+    const unsigned char *adata,  unsigned long adatalen,
+    const unsigned char *ct,     unsigned long ctlen,
+          unsigned char *pt,
+    const unsigned char *tag,    unsigned long taglen,
+          int           *stat)
+{
+   int            err;
+   ocb3_state     *ocb;
+   unsigned char *buf;
+   unsigned long  buflen;
+
+   LTC_ARGCHK(stat    != NULL);
+
+   /* default to zero */
+   *stat = 0;
+
+   /* limit taglen */
+   taglen = MIN(taglen, MAXBLOCKSIZE);
+
+   /* allocate memory */
+   buf = XMALLOC(taglen);
+   ocb = XMALLOC(sizeof(ocb3_state));
+   if (ocb == NULL || buf == NULL) {
+      if (ocb != NULL) {
+         XFREE(ocb);
+      }
+      if (buf != NULL) {
+         XFREE(buf);
+      }
+      return CRYPT_MEM;
+   }
+
+   if ((err = ocb3_init(ocb, cipher, key, keylen, nonce, noncelen, taglen)) != CRYPT_OK) {
+      goto LBL_ERR;
+   }
+
+   if (adata != NULL || adatalen != 0) {
+      if ((err = ocb3_add_aad(ocb, adata, adatalen)) != CRYPT_OK) {
+         goto LBL_ERR;
+      }
+   }
+
+   if ((err = ocb3_decrypt_last(ocb, ct, ctlen, pt)) != CRYPT_OK) {
+      goto LBL_ERR;
+   }
+
+   buflen = taglen;
+   if ((err = ocb3_done(ocb, buf, &buflen)) != CRYPT_OK) {
+      goto LBL_ERR;
+   }
+
+   /* compare tags */
+   if (buflen >= taglen && XMEM_NEQ(buf, tag, taglen) == 0) {
+      *stat = 1;
+   }
+
+   err = CRYPT_OK;
+
+LBL_ERR:
+#ifdef LTC_CLEAN_STACK
+   zeromem(ocb, sizeof(ocb3_state));
+#endif
+
+   XFREE(ocb);
+   XFREE(buf);
+   return err;
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */