X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fmodes%2Fcfb%2Fcfb_decrypt.c;fp=libtomcrypt%2Fsrc%2Fmodes%2Fcfb%2Fcfb_decrypt.c;h=9749a0bee0a1d52813342201e24b2557cdf96dd6;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/libtomcrypt/src/modes/cfb/cfb_decrypt.c b/libtomcrypt/src/modes/cfb/cfb_decrypt.c
new file mode 100644
index 0000000..9749a0b
--- /dev/null
+++ b/libtomcrypt/src/modes/cfb/cfb_decrypt.c
@@ -0,0 +1,65 @@
+/* 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.
+ */
+#include "tomcrypt.h"
+
+/**
+  @file cfb_decrypt.c
+  CFB implementation, decrypt data, Tom St Denis
+*/
+
+#ifdef LTC_CFB_MODE
+
+/**
+   CFB decrypt
+   @param ct      Ciphertext
+   @param pt      [out] Plaintext
+   @param len     Length of ciphertext (octets)
+   @param cfb     CFB state
+   @return CRYPT_OK if successful
+*/
+int cfb_decrypt(const unsigned char *ct, unsigned char *pt, unsigned long len, symmetric_CFB *cfb)
+{
+   int err;
+
+   LTC_ARGCHK(pt != NULL);
+   LTC_ARGCHK(ct != NULL);
+   LTC_ARGCHK(cfb != NULL);
+
+   if ((err = cipher_is_valid(cfb->cipher)) != CRYPT_OK) {
+       return err;
+   }
+
+   /* is blocklen/padlen valid? */
+   if (cfb->blocklen < 0 || cfb->blocklen > (int)sizeof(cfb->IV) ||
+       cfb->padlen   < 0 || cfb->padlen   > (int)sizeof(cfb->pad)) {
+      return CRYPT_INVALID_ARG;
+   }
+
+   while (len-- > 0) {
+       if (cfb->padlen == cfb->blocklen) {
+          if ((err = cipher_descriptor[cfb->cipher].ecb_encrypt(cfb->pad, cfb->IV, &cfb->key)) != CRYPT_OK) {
+             return err;
+          }
+          cfb->padlen = 0;
+       }
+       cfb->pad[cfb->padlen] = *ct;
+       *pt = *ct ^ cfb->IV[cfb->padlen];
+       ++pt;
+       ++ct;
+       ++(cfb->padlen);
+   }
+   return CRYPT_OK;
+}
+
+#endif
+
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */