ofb_start.c revision f7fc46c63fdc8f39234fea409b8dbe116d73ebf8 
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@gmail.com, http://libtomcrypt.com
10 */
11#include "tomcrypt.h"
12
13/**
14   @file ofb_start.c
15   OFB implementation, start chain, Tom St Denis
16*/
17
18
19#ifdef LTC_OFB_MODE
20
21/**
22   Initialize a OFB 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 ofb         The OFB state to initialize
29   @return CRYPT_OK if successful
30*/
31int ofb_start(int cipher, const unsigned char *IV, const unsigned char *key,
32              int keylen, int num_rounds, symmetric_OFB *ofb)
33{
34   int x, err;
35
36   LTC_ARGCHK(IV != NULL);
37   LTC_ARGCHK(key != NULL);
38   LTC_ARGCHK(ofb != NULL);
39
40   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
41      return err;
42   }
43
44   /* copy details */
45   ofb->cipher = cipher;
46   ofb->blocklen = cipher_descriptor[cipher].block_length;
47   for (x = 0; x < ofb->blocklen; x++) {
48       ofb->IV[x] = IV[x];
49   }
50
51   /* init the cipher */
52   ofb->padlen = ofb->blocklen;
53   return cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ofb->key);
54}
55
56#endif
57
58/* $Source: /cvs/libtom/libtomcrypt/src/modes/ofb/ofb_start.c,v $ */
59/* $Revision: 1.5 $ */
60/* $Date: 2006/06/29 01:51:34 $ */
61