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comparison src/modes/ctr/ctr_start.c @ 191:1c15b283127b libtomcrypt-orig

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Import of libtomcrypt 1.02 with manual path rename rearrangement etc
author Matt Johnston <matt@ucc.asn.au>
date Fri, 06 May 2005 13:23:02 +0000
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children 39d5d58461d6
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143:5d99163f7e32 191:1c15b283127b
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, [email protected], http://libtomcrypt.org
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file ctr_start.c
15 CTR implementation, start chain, Tom St Denis
16 */
17
18
19 #ifdef CTR
20
21 /**
22 Initialize a CTR context
23 @param cipher The index of the cipher desired
24 @param count 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 ctr The CTR state to initialize
29 @return CRYPT_OK if successful
30 */
31 int ctr_start(int cipher, const unsigned char *count, const unsigned char *key, int keylen,
32 int num_rounds, symmetric_CTR *ctr)
33 {
34 int x, err;
35
36 LTC_ARGCHK(count != NULL);
37 LTC_ARGCHK(key != NULL);
38 LTC_ARGCHK(ctr != NULL);
39
40 /* bad param? */
41 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
42 return err;
43 }
44
45 /* setup cipher */
46 if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) {
47 return err;
48 }
49
50 /* copy ctr */
51 ctr->blocklen = cipher_descriptor[cipher].block_length;
52 ctr->cipher = cipher;
53 ctr->padlen = 0;
54 ctr->mode = 0;
55 for (x = 0; x < ctr->blocklen; x++) {
56 ctr->ctr[x] = count[x];
57 }
58 cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key);
59 return CRYPT_OK;
60 }
61
62 #endif