1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis 2 * 3 * LibTomCrypt is a library that provides various cryptographic 4 * algorithms in a highly modular and flexible manner. 5 * 6 * The library is free for all purposes without any express 7 * guarantee it works. 8 * 9 * Tom St Denis, tomstdenis (at) gmail.com, http://libtomcrypt.com 10 */ 11 #include "tomcrypt.h" 12 13 /** 14 @file cfb_start.c 15 CFB implementation, start chain, Tom St Denis 16 */ 17 18 19 #ifdef LTC_CFB_MODE 20 21 /** 22 Initialize a CFB context 23 @param cipher The index of the cipher desired 24 @param IV The initial vector 25 @param key The secret key 26 @param keylen The length of the secret key (octets) 27 @param num_rounds Number of rounds in the cipher desired (0 for default) 28 @param cfb The CFB state to initialize 29 @return CRYPT_OK if successful 30 */ 31 int cfb_start(int cipher, const unsigned char *IV, const unsigned char *key, 32 int keylen, int num_rounds, symmetric_CFB *cfb) 33 { 34 int x, err; 35 36 LTC_ARGCHK(IV != NULL); 37 LTC_ARGCHK(key != NULL); 38 LTC_ARGCHK(cfb != NULL); 39 40 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { 41 return err; 42 } 43 44 45 /* copy data */ 46 cfb->cipher = cipher; 47 cfb->blocklen = cipher_descriptor[cipher].block_length; 48 for (x = 0; x < cfb->blocklen; x++) 49 cfb->IV[x] = IV[x]; 50 51 /* init the cipher */ 52 if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &cfb->key)) != CRYPT_OK) { 53 return err; 54 } 55 56 /* encrypt the IV */ 57 cfb->padlen = 0; 58 return cipher_descriptor[cfb->cipher].ecb_encrypt(cfb->IV, cfb->IV, &cfb->key); 59 } 60 61 #endif 62 63 /* $Source: /cvs/libtom/libtomcrypt/src/modes/cfb/cfb_start.c,v $ */ 64 /* $Revision: 1.6 $ */ 65 /* $Date: 2006/06/29 01:51:34 $ */ 66
