diff options
Diffstat (limited to 'core/lib/libtomcrypt/src/modes/cfb/cfb_decrypt.c')
-rw-r--r-- | core/lib/libtomcrypt/src/modes/cfb/cfb_decrypt.c | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/core/lib/libtomcrypt/src/modes/cfb/cfb_decrypt.c b/core/lib/libtomcrypt/src/modes/cfb/cfb_decrypt.c new file mode 100644 index 0000000..7ca938f --- /dev/null +++ b/core/lib/libtomcrypt/src/modes/cfb/cfb_decrypt.c @@ -0,0 +1,94 @@ +/* + * Copyright (c) 2001-2007, Tom St Denis + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright notice, + * this list of conditions and the following disclaimer in the documentation + * and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + */ + +/* 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, tomstdenis@gmail.com, http://libtom.org + */ +#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 + + +/* $Source: /cvs/libtom/libtomcrypt/src/modes/cfb/cfb_decrypt.c,v $ */ +/* $Revision: 1.8 $ */ +/* $Date: 2006/12/28 01:27:24 $ */ |