Mercurial > dropbear

annotate src/modes/cfb/cfb_decrypt.c @ 390:d8e44bef7917 libtomcrypt-dropbear

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Replace // with /* */
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 04:28:09 +0000
parents d5faf4814ddb
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
2 *
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
3 * LibTomCrypt is a library that provides various cryptographic
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
4 * algorithms in a highly modular and flexible manner.
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
5 *
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
6 * The library is free for all purposes without any express
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
7 * guarantee it works.
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
8 *
380
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
9 * Tom St Denis, [email protected], http://libtomcrypt.com
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
10 */
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
11 #include "tomcrypt.h"
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
12
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
13 /**
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
14 @file cfb_decrypt.c
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
15 CFB implementation, decrypt data, Tom St Denis
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
16 */
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
17
380
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
18 #ifdef LTC_CFB_MODE
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
19
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
20 /**
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
21 CFB decrypt
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
22 @param ct Ciphertext
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
23 @param pt [out] Plaintext
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
24 @param len Length of ciphertext (octets)
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
25 @param cfb CFB state
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
26 @return CRYPT_OK if successful
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
27 */
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
28 int cfb_decrypt(const unsigned char *ct, unsigned char *pt, unsigned long len, symmetric_CFB *cfb)
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
29 {
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
30 int err;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
31
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
32 LTC_ARGCHK(pt != NULL);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
33 LTC_ARGCHK(ct != NULL);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
34 LTC_ARGCHK(cfb != NULL);
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
35
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
36 if ((err = cipher_is_valid(cfb->cipher)) != CRYPT_OK) {
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
37 return err;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
38 }
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
39
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
40 /* is blocklen/padlen valid? */
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
41 if (cfb->blocklen < 0 || cfb->blocklen > (int)sizeof(cfb->IV) ||
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
42 cfb->padlen < 0 || cfb->padlen > (int)sizeof(cfb->pad)) {
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
43 return CRYPT_INVALID_ARG;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
44 }
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
45
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
46 while (len-- > 0) {
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
47 if (cfb->padlen == cfb->blocklen) {
380
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
48 if ((err = cipher_descriptor[cfb->cipher].ecb_encrypt(cfb->pad, cfb->IV, &cfb->key)) != CRYPT_OK) {
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
49 return err;
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
50 }
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
51 cfb->padlen = 0;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
52 }
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
53 cfb->pad[cfb->padlen] = *ct;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
54 *pt = *ct ^ cfb->IV[cfb->padlen];
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
55 ++pt;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
56 ++ct;
380
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
57 ++(cfb->padlen);
280
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
58 }
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
59 return CRYPT_OK;
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
60 }
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
61
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
62 #endif
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
63
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
64
59400faa4b44 Re-import libtomcrypt 1.05 for cleaner propagating.
Matt Johnston <matt@ucc.asn.au>
parents:
diff changeset
65 /* $Source: /cvs/libtom/libtomcrypt/src/modes/cfb/cfb_decrypt.c,v $ */
380
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
66 /* $Revision: 1.7 $ */
d5faf4814ddb Update to LibTomCrypt 1.16
Matt Johnston <matt@ucc.asn.au>
parents: 280
diff changeset
67 /* $Date: 2006/11/26 01:45:14 $ */