Mercurial > dropbear

comparison libtomcrypt/src/encauth/gcm/gcm_done.c @ 391:00fcf5045160

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head c1db4398d56c56c6d06ae1e20c1e0d04dbb598ed) to branch 'au.asn.ucc.matt.dropbear' (head d26d5eb2837f46b56a33fb0e7573aa0201abd4d5)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 04:29:08 +0000
parents 0cbe8f6dbf9e
children f849a5ca2efc
comparison
equal deleted inserted replaced
390:d8e44bef7917 391:00fcf5045160
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.com
10 */
11
12 /**
13 @file gcm_done.c
14 GCM implementation, Terminate the stream, by Tom St Denis
15 */
16 #include "tomcrypt.h"
17
18 #ifdef GCM_MODE
19
20 /**
21 Terminate a GCM stream
22 @param gcm The GCM state
23 @param tag [out] The destination for the MAC tag
24 @param taglen [in/out] The length of the MAC tag
25 @return CRYPT_OK on success
26 */
27 int gcm_done(gcm_state *gcm,
28 unsigned char *tag, unsigned long *taglen)
29 {
30 unsigned long x;
31 int err;
32
33 LTC_ARGCHK(gcm != NULL);
34 LTC_ARGCHK(tag != NULL);
35 LTC_ARGCHK(taglen != NULL);
36
37 if (gcm->buflen > 16 || gcm->buflen < 0) {
38 return CRYPT_INVALID_ARG;
39 }
40
41 if ((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) {
42 return err;
43 }
44
45
46 if (gcm->mode != GCM_MODE_TEXT) {
47 return CRYPT_INVALID_ARG;
48 }
49
50 /* handle remaining ciphertext */
51 if (gcm->buflen) {
52 gcm->pttotlen += gcm->buflen * CONST64(8);
53 gcm_mult_h(gcm, gcm->X);
54 }
55
56 /* length */
57 STORE64H(gcm->totlen, gcm->buf);
58 STORE64H(gcm->pttotlen, gcm->buf+8);
59 for (x = 0; x < 16; x++) {
60 gcm->X[x] ^= gcm->buf[x];
61 }
62 gcm_mult_h(gcm, gcm->X);
63
64 /* encrypt original counter */
65 if ((err = cipher_descriptor[gcm->cipher].ecb_encrypt(gcm->Y_0, gcm->buf, &gcm->K)) != CRYPT_OK) {
66 return err;
67 }
68 for (x = 0; x < 16 && x < *taglen; x++) {
69 tag[x] = gcm->buf[x] ^ gcm->X[x];
70 }
71 *taglen = x;
72
73 cipher_descriptor[gcm->cipher].done(&gcm->K);
74
75 return CRYPT_OK;
76 }
77
78 #endif
79
80
81 /* $Source: /cvs/libtom/libtomcrypt/src/encauth/gcm/gcm_done.c,v $ */
82 /* $Revision: 1.9 $ */
83 /* $Date: 2006/03/31 14:15:35 $ */