Root/crypto/tea.c

1/*
2 * Cryptographic API.
3 *
4 * TEA, XTEA, and XETA crypto alogrithms
5 *
6 * The TEA and Xtended TEA algorithms were developed by David Wheeler
7 * and Roger Needham at the Computer Laboratory of Cambridge University.
8 *
9 * Due to the order of evaluation in XTEA many people have incorrectly
10 * implemented it. XETA (XTEA in the wrong order), exists for
11 * compatibility with these implementations.
12 *
13 * Copyright (c) 2004 Aaron Grothe ajgrothe@yahoo.com
14 *
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
19 *
20 */
21
22#include <linux/init.h>
23#include <linux/module.h>
24#include <linux/mm.h>
25#include <asm/byteorder.h>
26#include <linux/crypto.h>
27#include <linux/types.h>
28
29#define TEA_KEY_SIZE 16
30#define TEA_BLOCK_SIZE 8
31#define TEA_ROUNDS 32
32#define TEA_DELTA 0x9e3779b9
33
34#define XTEA_KEY_SIZE 16
35#define XTEA_BLOCK_SIZE 8
36#define XTEA_ROUNDS 32
37#define XTEA_DELTA 0x9e3779b9
38
39struct tea_ctx {
40    u32 KEY[4];
41};
42
43struct xtea_ctx {
44    u32 KEY[4];
45};
46
47static int tea_setkey(struct crypto_tfm *tfm, const u8 *in_key,
48              unsigned int key_len)
49{
50    struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
51    const __le32 *key = (const __le32 *)in_key;
52
53    ctx->KEY[0] = le32_to_cpu(key[0]);
54    ctx->KEY[1] = le32_to_cpu(key[1]);
55    ctx->KEY[2] = le32_to_cpu(key[2]);
56    ctx->KEY[3] = le32_to_cpu(key[3]);
57
58    return 0;
59
60}
61
62static void tea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
63{
64    u32 y, z, n, sum = 0;
65    u32 k0, k1, k2, k3;
66    struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
67    const __le32 *in = (const __le32 *)src;
68    __le32 *out = (__le32 *)dst;
69
70    y = le32_to_cpu(in[0]);
71    z = le32_to_cpu(in[1]);
72
73    k0 = ctx->KEY[0];
74    k1 = ctx->KEY[1];
75    k2 = ctx->KEY[2];
76    k3 = ctx->KEY[3];
77
78    n = TEA_ROUNDS;
79
80    while (n-- > 0) {
81        sum += TEA_DELTA;
82        y += ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
83        z += ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
84    }
85    
86    out[0] = cpu_to_le32(y);
87    out[1] = cpu_to_le32(z);
88}
89
90static void tea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
91{
92    u32 y, z, n, sum;
93    u32 k0, k1, k2, k3;
94    struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
95    const __le32 *in = (const __le32 *)src;
96    __le32 *out = (__le32 *)dst;
97
98    y = le32_to_cpu(in[0]);
99    z = le32_to_cpu(in[1]);
100
101    k0 = ctx->KEY[0];
102    k1 = ctx->KEY[1];
103    k2 = ctx->KEY[2];
104    k3 = ctx->KEY[3];
105
106    sum = TEA_DELTA << 5;
107
108    n = TEA_ROUNDS;
109
110    while (n-- > 0) {
111        z -= ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
112        y -= ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
113        sum -= TEA_DELTA;
114    }
115    
116    out[0] = cpu_to_le32(y);
117    out[1] = cpu_to_le32(z);
118}
119
120static int xtea_setkey(struct crypto_tfm *tfm, const u8 *in_key,
121               unsigned int key_len)
122{
123    struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
124    const __le32 *key = (const __le32 *)in_key;
125
126    ctx->KEY[0] = le32_to_cpu(key[0]);
127    ctx->KEY[1] = le32_to_cpu(key[1]);
128    ctx->KEY[2] = le32_to_cpu(key[2]);
129    ctx->KEY[3] = le32_to_cpu(key[3]);
130
131    return 0;
132
133}
134
135static void xtea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
136{
137    u32 y, z, sum = 0;
138    u32 limit = XTEA_DELTA * XTEA_ROUNDS;
139    struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
140    const __le32 *in = (const __le32 *)src;
141    __le32 *out = (__le32 *)dst;
142
143    y = le32_to_cpu(in[0]);
144    z = le32_to_cpu(in[1]);
145
146    while (sum != limit) {
147        y += ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum&3]);
148        sum += XTEA_DELTA;
149        z += ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 &3]);
150    }
151    
152    out[0] = cpu_to_le32(y);
153    out[1] = cpu_to_le32(z);
154}
155
156static void xtea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
157{
158    u32 y, z, sum;
159    struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
160    const __le32 *in = (const __le32 *)src;
161    __le32 *out = (__le32 *)dst;
162
163    y = le32_to_cpu(in[0]);
164    z = le32_to_cpu(in[1]);
165
166    sum = XTEA_DELTA * XTEA_ROUNDS;
167
168    while (sum) {
169        z -= ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 & 3]);
170        sum -= XTEA_DELTA;
171        y -= ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum & 3]);
172    }
173    
174    out[0] = cpu_to_le32(y);
175    out[1] = cpu_to_le32(z);
176}
177
178
179static void xeta_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
180{
181    u32 y, z, sum = 0;
182    u32 limit = XTEA_DELTA * XTEA_ROUNDS;
183    struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
184    const __le32 *in = (const __le32 *)src;
185    __le32 *out = (__le32 *)dst;
186
187    y = le32_to_cpu(in[0]);
188    z = le32_to_cpu(in[1]);
189
190    while (sum != limit) {
191        y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3];
192        sum += XTEA_DELTA;
193        z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3];
194    }
195    
196    out[0] = cpu_to_le32(y);
197    out[1] = cpu_to_le32(z);
198}
199
200static void xeta_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
201{
202    u32 y, z, sum;
203    struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
204    const __le32 *in = (const __le32 *)src;
205    __le32 *out = (__le32 *)dst;
206
207    y = le32_to_cpu(in[0]);
208    z = le32_to_cpu(in[1]);
209
210    sum = XTEA_DELTA * XTEA_ROUNDS;
211
212    while (sum) {
213        z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3];
214        sum -= XTEA_DELTA;
215        y -= (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum & 3];
216    }
217    
218    out[0] = cpu_to_le32(y);
219    out[1] = cpu_to_le32(z);
220}
221
222static struct crypto_alg tea_algs[3] = { {
223    .cra_name = "tea",
224    .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
225    .cra_blocksize = TEA_BLOCK_SIZE,
226    .cra_ctxsize = sizeof (struct tea_ctx),
227    .cra_alignmask = 3,
228    .cra_module = THIS_MODULE,
229    .cra_u = { .cipher = {
230    .cia_min_keysize = TEA_KEY_SIZE,
231    .cia_max_keysize = TEA_KEY_SIZE,
232    .cia_setkey = tea_setkey,
233    .cia_encrypt = tea_encrypt,
234    .cia_decrypt = tea_decrypt } }
235}, {
236    .cra_name = "xtea",
237    .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
238    .cra_blocksize = XTEA_BLOCK_SIZE,
239    .cra_ctxsize = sizeof (struct xtea_ctx),
240    .cra_alignmask = 3,
241    .cra_module = THIS_MODULE,
242    .cra_u = { .cipher = {
243    .cia_min_keysize = XTEA_KEY_SIZE,
244    .cia_max_keysize = XTEA_KEY_SIZE,
245    .cia_setkey = xtea_setkey,
246    .cia_encrypt = xtea_encrypt,
247    .cia_decrypt = xtea_decrypt } }
248}, {
249    .cra_name = "xeta",
250    .cra_flags = CRYPTO_ALG_TYPE_CIPHER,
251    .cra_blocksize = XTEA_BLOCK_SIZE,
252    .cra_ctxsize = sizeof (struct xtea_ctx),
253    .cra_alignmask = 3,
254    .cra_module = THIS_MODULE,
255    .cra_u = { .cipher = {
256    .cia_min_keysize = XTEA_KEY_SIZE,
257    .cia_max_keysize = XTEA_KEY_SIZE,
258    .cia_setkey = xtea_setkey,
259    .cia_encrypt = xeta_encrypt,
260    .cia_decrypt = xeta_decrypt } }
261} };
262
263static int __init tea_mod_init(void)
264{
265    return crypto_register_algs(tea_algs, ARRAY_SIZE(tea_algs));
266}
267
268static void __exit tea_mod_fini(void)
269{
270    crypto_unregister_algs(tea_algs, ARRAY_SIZE(tea_algs));
271}
272
273MODULE_ALIAS("xtea");
274MODULE_ALIAS("xeta");
275
276module_init(tea_mod_init);
277module_exit(tea_mod_fini);
278
279MODULE_LICENSE("GPL");
280MODULE_DESCRIPTION("TEA, XTEA & XETA Cryptographic Algorithms");
281

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