aboutsummaryrefslogtreecommitdiff
path: root/crypto/tea.c
blob: 03c23cbd3afa1f6373d964b308463701ab316458 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
/* 
 * Cryptographic API.
 *
 * TEA and Xtended TEA Algorithms
 *
 * The TEA and Xtended TEA algorithms were developed by David Wheeler 
 * and Roger Needham at the Computer Laboratory of Cambridge University.
 *
 * Copyright (c) 2004 Aaron Grothe ajgrothe@yahoo.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <asm/scatterlist.h>
#include <linux/crypto.h>

#define TEA_KEY_SIZE		16
#define TEA_BLOCK_SIZE		8
#define TEA_ROUNDS		32
#define TEA_DELTA		0x9e3779b9

#define XTEA_KEY_SIZE		16
#define XTEA_BLOCK_SIZE		8
#define XTEA_ROUNDS		32
#define XTEA_DELTA		0x9e3779b9

#define u32_in(x) le32_to_cpu(*(const __le32 *)(x))
#define u32_out(to, from) (*(__le32 *)(to) = cpu_to_le32(from))

struct tea_ctx {
	u32 KEY[4];
};

struct xtea_ctx {
	u32 KEY[4];
};

static int tea_setkey(void *ctx_arg, const u8 *in_key,
                       unsigned int key_len, u32 *flags)
{ 

	struct tea_ctx *ctx = ctx_arg;
	
	if (key_len != 16)
	{
		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	}

	ctx->KEY[0] = u32_in (in_key);
	ctx->KEY[1] = u32_in (in_key + 4);
	ctx->KEY[2] = u32_in (in_key + 8);
	ctx->KEY[3] = u32_in (in_key + 12);

	return 0; 

}

static void tea_encrypt(void *ctx_arg, u8 *dst, const u8 *src)
{ 
	u32 y, z, n, sum = 0;
	u32 k0, k1, k2, k3;

	struct tea_ctx *ctx = ctx_arg;

	y = u32_in (src);
	z = u32_in (src + 4);

	k0 = ctx->KEY[0];
	k1 = ctx->KEY[1];
	k2 = ctx->KEY[2];
	k3 = ctx->KEY[3];

	n = TEA_ROUNDS;

	while (n-- > 0) {
		sum += TEA_DELTA;
		y += ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
		z += ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
	}
	
	u32_out (dst, y);
	u32_out (dst + 4, z);
}

static void tea_decrypt(void *ctx_arg, u8 *dst, const u8 *src)
{ 
	u32 y, z, n, sum;
	u32 k0, k1, k2, k3;

	struct tea_ctx *ctx = ctx_arg;

	y = u32_in (src);
	z = u32_in (src + 4);

	k0 = ctx->KEY[0];
	k1 = ctx->KEY[1];
	k2 = ctx->KEY[2];
	k3 = ctx->KEY[3];

	sum = TEA_DELTA << 5;

	n = TEA_ROUNDS;

	while (n-- > 0) {
		z -= ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
		y -= ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
		sum -= TEA_DELTA;
	}
	
	u32_out (dst, y);
	u32_out (dst + 4, z);

}

static int xtea_setkey(void *ctx_arg, const u8 *in_key,
                       unsigned int key_len, u32 *flags)
{ 

	struct xtea_ctx *ctx = ctx_arg;
	
	if (key_len != 16)
	{
		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	}

	ctx->KEY[0] = u32_in (in_key);
	ctx->KEY[1] = u32_in (in_key + 4);
	ctx->KEY[2] = u32_in (in_key + 8);
	ctx->KEY[3] = u32_in (in_key + 12);

	return 0; 

}

static void xtea_encrypt(void *ctx_arg, u8 *dst, const u8 *src)
{ 

	u32 y, z, sum = 0;
	u32 limit = XTEA_DELTA * XTEA_ROUNDS;

	struct xtea_ctx *ctx = ctx_arg;

	y = u32_in (src);
	z = u32_in (src + 4);

	while (sum != limit) {
		y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3]; 
		sum += XTEA_DELTA;
		z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3]; 
	}
	
	u32_out (dst, y);
	u32_out (dst + 4, z);

}

static void xtea_decrypt(void *ctx_arg, u8 *dst, const u8 *src)
{ 

	u32 y, z, sum;
	struct tea_ctx *ctx = ctx_arg;

	y = u32_in (src);
	z = u32_in (src + 4);

	sum = XTEA_DELTA * XTEA_ROUNDS;

	while (sum) {
		z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3];
		sum -= XTEA_DELTA;
		y -= (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum & 3];
	}
	
	u32_out (dst, y);
	u32_out (dst + 4, z);

}

static struct crypto_alg tea_alg = {
	.cra_name		=	"tea",
	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
	.cra_blocksize		=	TEA_BLOCK_SIZE,
	.cra_ctxsize		=	sizeof (struct tea_ctx),
	.cra_module		=	THIS_MODULE,
	.cra_list		=	LIST_HEAD_INIT(tea_alg.cra_list),
	.cra_u			=	{ .cipher = {
	.cia_min_keysize	=	TEA_KEY_SIZE,
	.cia_max_keysize	=	TEA_KEY_SIZE,
	.cia_setkey		= 	tea_setkey,
	.cia_encrypt		=	tea_encrypt,
	.cia_decrypt		=	tea_decrypt } }
};

static struct crypto_alg xtea_alg = {
	.cra_name		=	"xtea",
	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
	.cra_blocksize		=	XTEA_BLOCK_SIZE,
	.cra_ctxsize		=	sizeof (struct xtea_ctx),
	.cra_module		=	THIS_MODULE,
	.cra_list		=	LIST_HEAD_INIT(xtea_alg.cra_list),
	.cra_u			=	{ .cipher = {
	.cia_min_keysize	=	XTEA_KEY_SIZE,
	.cia_max_keysize	=	XTEA_KEY_SIZE,
	.cia_setkey		= 	xtea_setkey,
	.cia_encrypt		=	xtea_encrypt,
	.cia_decrypt		=	xtea_decrypt } }
};

static int __init init(void)
{
	int ret = 0;
	
	ret = crypto_register_alg(&tea_alg);
	if (ret < 0)
		goto out;

	ret = crypto_register_alg(&xtea_alg);
	if (ret < 0) {
		crypto_unregister_alg(&tea_alg);
		goto out;
	}

out:	
	return ret;
}

static void __exit fini(void)
{
	crypto_unregister_alg(&tea_alg);
	crypto_unregister_alg(&xtea_alg);
}

MODULE_ALIAS("xtea");

module_init(init);
module_exit(fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("TEA & XTEA Cryptographic Algorithms");