Mercurial > dropbear

comparison libtomcrypt/src/modes/lrw/lrw_process.c @ 382:0cbe8f6dbf9e

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 2af22fb4e878750b88f80f90d439b316d229796f) to branch 'au.asn.ucc.matt.dropbear' (head 02c413252c90e9de8e03d91e9939dde3029f5c0a)
author Matt Johnston <matt@ucc.asn.au>
date Thu, 11 Jan 2007 02:41:05 +0000
parents
children f849a5ca2efc
comparison
equal deleted inserted replaced
379:b66a00272a90 382:0cbe8f6dbf9e
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 #include "tomcrypt.h"
12
13 /**
14 @file lrw_process.c
15 LRW_MODE implementation, Encrypt/decrypt blocks, Tom St Denis
16 */
17
18 #ifdef LTC_LRW_MODE
19
20 /**
21 Process blocks with LRW, since decrypt/encrypt are largely the same they share this code.
22 @param pt The "input" data
23 @param ct [out] The "output" data
24 @param len The length of the input, must be a multiple of 128-bits (16 octets)
25 @param mode LRW_ENCRYPT or LRW_DECRYPT
26 @param lrw The LRW state
27 @return CRYPT_OK if successful
28 */
29 int lrw_process(const unsigned char *pt, unsigned char *ct, unsigned long len, int mode, symmetric_LRW *lrw)
30 {
31 unsigned char prod[16];
32 int x, err;
33 #ifdef LRW_TABLES
34 int y;
35 #endif
36
37 LTC_ARGCHK(pt != NULL);
38 LTC_ARGCHK(ct != NULL);
39 LTC_ARGCHK(lrw != NULL);
40
41 if (len & 15) {
42 return CRYPT_INVALID_ARG;
43 }
44
45 while (len) {
46 /* copy pad */
47 XMEMCPY(prod, lrw->pad, 16);
48
49 /* increment IV */
50 for (x = 15; x >= 0; x--) {
51 lrw->IV[x] = (lrw->IV[x] + 1) & 255;
52 if (lrw->IV[x]) {
53 break;
54 }
55 }
56
57 /* update pad */
58 #ifdef LRW_TABLES
59 /* for each byte changed we undo it's affect on the pad then add the new product */
60 for (; x < 16; x++) {
61 #ifdef LTC_FAST
62 for (y = 0; y < 16; y += sizeof(LTC_FAST_TYPE)) {
63 *((LTC_FAST_TYPE *)(lrw->pad + y)) ^= *((LTC_FAST_TYPE *)(&lrw->PC[x][lrw->IV[x]][y])) ^ *((LTC_FAST_TYPE *)(&lrw->PC[x][(lrw->IV[x]-1)&255][y]));
64 }
65 #else
66 for (y = 0; y < 16; y++) {
67 lrw->pad[y] ^= lrw->PC[x][lrw->IV[x]][y] ^ lrw->PC[x][(lrw->IV[x]-1)&255][y];
68 }
69 #endif
70 }
71 #else
72 gcm_gf_mult(lrw->tweak, lrw->IV, lrw->pad);
73 #endif
74
75 /* xor prod */
76 #ifdef LTC_FAST
77 for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
78 *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(pt + x)) ^ *((LTC_FAST_TYPE *)(prod + x));
79 }
80 #else
81 for (x = 0; x < 16; x++) {
82 ct[x] = pt[x] ^ prod[x];
83 }
84 #endif
85
86 /* send through cipher */
87 if (mode == LRW_ENCRYPT) {
88 if ((err = cipher_descriptor[lrw->cipher].ecb_encrypt(ct, ct, &lrw->key)) != CRYPT_OK) {
89 return err;
90 }
91 } else {
92 if ((err = cipher_descriptor[lrw->cipher].ecb_decrypt(ct, ct, &lrw->key)) != CRYPT_OK) {
93 return err;
94 }
95 }
96
97 /* xor prod */
98 #ifdef LTC_FAST
99 for (x = 0; x < 16; x += sizeof(LTC_FAST_TYPE)) {
100 *((LTC_FAST_TYPE *)(ct + x)) = *((LTC_FAST_TYPE *)(ct + x)) ^ *((LTC_FAST_TYPE *)(prod + x));
101 }
102 #else
103 for (x = 0; x < 16; x++) {
104 ct[x] = ct[x] ^ prod[x];
105 }
106 #endif
107
108 /* move to next */
109 pt += 16;
110 ct += 16;
111 len -= 16;
112 }
113
114 return CRYPT_OK;
115 }
116
117 #endif
118 /* $Source: /cvs/libtom/libtomcrypt/src/modes/lrw/lrw_process.c,v $ */
119 /* $Revision: 1.10 $ */
120 /* $Date: 2006/06/29 01:53:13 $ */