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comparison libtomcrypt/src/modes/lrw/lrw_process.c @ 398:59c7938af2bd

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merge of '1250b8af44b62d8f4fe0f8d9fc7e7a1cc34e7e1c' and '7f8670ac3bb975f40967f3979d09d2199b7e90c8'
author Matt Johnston <matt@ucc.asn.au>
date Sat, 03 Feb 2007 08:20:30 +0000
parents 0cbe8f6dbf9e
children f849a5ca2efc
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396:e7c1a77d2921 398:59c7938af2bd
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 $ */