--- /dev/null
+/* 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: $Format:%ai$ */