tea.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* 
  3 * Cryptographic API.
  4 *
  5 * TEA, XTEA, and XETA crypto alogrithms
  6 *
  7 * The TEA and Xtended TEA algorithms were developed by David Wheeler 
  8 * and Roger Needham at the Computer Laboratory of Cambridge University.
  9 *
 10 * Due to the order of evaluation in XTEA many people have incorrectly
 11 * implemented it.  XETA (XTEA in the wrong order), exists for
 12 * compatibility with these implementations.
 13 *
 14 * Copyright (c) 2004 Aaron Grothe ajgrothe@yahoo.com
 15 */
 16
 17#include <crypto/algapi.h>
 18#include <linux/init.h>
 19#include <linux/module.h>
 20#include <linux/mm.h>
 21#include <linux/unaligned.h>
 22#include <linux/types.h>
 23
 24#define TEA_KEY_SIZE		16
 25#define TEA_BLOCK_SIZE		8
 26#define TEA_ROUNDS		32
 27#define TEA_DELTA		0x9e3779b9
 28
 29#define XTEA_KEY_SIZE		16
 30#define XTEA_BLOCK_SIZE		8
 31#define XTEA_ROUNDS		32
 32#define XTEA_DELTA		0x9e3779b9
 33
 34struct tea_ctx {
 35	u32 KEY[4];
 36};
 37
 38struct xtea_ctx {
 39	u32 KEY[4];
 40};
 41
 42static int tea_setkey(struct crypto_tfm *tfm, const u8 *in_key,
 43		      unsigned int key_len)
 44{
 45	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
 46
 47	ctx->KEY[0] = get_unaligned_le32(&in_key[0]);
 48	ctx->KEY[1] = get_unaligned_le32(&in_key[4]);
 49	ctx->KEY[2] = get_unaligned_le32(&in_key[8]);
 50	ctx->KEY[3] = get_unaligned_le32(&in_key[12]);
 51
 52	return 0; 
 53
 54}
 55
 56static void tea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
 57{
 58	u32 y, z, n, sum = 0;
 59	u32 k0, k1, k2, k3;
 60	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
 61
 62	y = get_unaligned_le32(&src[0]);
 63	z = get_unaligned_le32(&src[4]);
 64
 65	k0 = ctx->KEY[0];
 66	k1 = ctx->KEY[1];
 67	k2 = ctx->KEY[2];
 68	k3 = ctx->KEY[3];
 69
 70	n = TEA_ROUNDS;
 71
 72	while (n-- > 0) {
 73		sum += TEA_DELTA;
 74		y += ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
 75		z += ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
 76	}
 77	
 78	put_unaligned_le32(y, &dst[0]);
 79	put_unaligned_le32(z, &dst[4]);
 80}
 81
 82static void tea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
 83{
 84	u32 y, z, n, sum;
 85	u32 k0, k1, k2, k3;
 86	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
 87
 88	y = get_unaligned_le32(&src[0]);
 89	z = get_unaligned_le32(&src[4]);
 90
 91	k0 = ctx->KEY[0];
 92	k1 = ctx->KEY[1];
 93	k2 = ctx->KEY[2];
 94	k3 = ctx->KEY[3];
 95
 96	sum = TEA_DELTA << 5;
 97
 98	n = TEA_ROUNDS;
 99
100	while (n-- > 0) {
101		z -= ((y << 4) + k2) ^ (y + sum) ^ ((y >> 5) + k3);
102		y -= ((z << 4) + k0) ^ (z + sum) ^ ((z >> 5) + k1);
103		sum -= TEA_DELTA;
104	}
105	
106	put_unaligned_le32(y, &dst[0]);
107	put_unaligned_le32(z, &dst[4]);
108}
109
110static int xtea_setkey(struct crypto_tfm *tfm, const u8 *in_key,
111		       unsigned int key_len)
112{
113	struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
114
115	ctx->KEY[0] = get_unaligned_le32(&in_key[0]);
116	ctx->KEY[1] = get_unaligned_le32(&in_key[4]);
117	ctx->KEY[2] = get_unaligned_le32(&in_key[8]);
118	ctx->KEY[3] = get_unaligned_le32(&in_key[12]);
119
120	return 0; 
121
122}
123
124static void xtea_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
125{
126	u32 y, z, sum = 0;
127	u32 limit = XTEA_DELTA * XTEA_ROUNDS;
128	struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
129
130	y = get_unaligned_le32(&src[0]);
131	z = get_unaligned_le32(&src[4]);
132
133	while (sum != limit) {
134		y += ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum&3]); 
135		sum += XTEA_DELTA;
136		z += ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 &3]); 
137	}
138	
139	put_unaligned_le32(y, &dst[0]);
140	put_unaligned_le32(z, &dst[4]);
141}
142
143static void xtea_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
144{
145	u32 y, z, sum;
146	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
147
148	y = get_unaligned_le32(&src[0]);
149	z = get_unaligned_le32(&src[4]);
150
151	sum = XTEA_DELTA * XTEA_ROUNDS;
152
153	while (sum) {
154		z -= ((y << 4 ^ y >> 5) + y) ^ (sum + ctx->KEY[sum>>11 & 3]);
155		sum -= XTEA_DELTA;
156		y -= ((z << 4 ^ z >> 5) + z) ^ (sum + ctx->KEY[sum & 3]);
157	}
158	
159	put_unaligned_le32(y, &dst[0]);
160	put_unaligned_le32(z, &dst[4]);
161}
162
163
164static void xeta_encrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
165{
166	u32 y, z, sum = 0;
167	u32 limit = XTEA_DELTA * XTEA_ROUNDS;
168	struct xtea_ctx *ctx = crypto_tfm_ctx(tfm);
169
170	y = get_unaligned_le32(&src[0]);
171	z = get_unaligned_le32(&src[4]);
172
173	while (sum != limit) {
174		y += (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum&3];
175		sum += XTEA_DELTA;
176		z += (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 &3];
177	}
178	
179	put_unaligned_le32(y, &dst[0]);
180	put_unaligned_le32(z, &dst[4]);
181}
182
183static void xeta_decrypt(struct crypto_tfm *tfm, u8 *dst, const u8 *src)
184{
185	u32 y, z, sum;
186	struct tea_ctx *ctx = crypto_tfm_ctx(tfm);
187
188	y = get_unaligned_le32(&src[0]);
189	z = get_unaligned_le32(&src[4]);
190
191	sum = XTEA_DELTA * XTEA_ROUNDS;
192
193	while (sum) {
194		z -= (y << 4 ^ y >> 5) + (y ^ sum) + ctx->KEY[sum>>11 & 3];
195		sum -= XTEA_DELTA;
196		y -= (z << 4 ^ z >> 5) + (z ^ sum) + ctx->KEY[sum & 3];
197	}
198	
199	put_unaligned_le32(y, &dst[0]);
200	put_unaligned_le32(z, &dst[4]);
201}
202
203static struct crypto_alg tea_algs[3] = { {
204	.cra_name		=	"tea",
205	.cra_driver_name	=	"tea-generic",
206	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
207	.cra_blocksize		=	TEA_BLOCK_SIZE,
208	.cra_ctxsize		=	sizeof (struct tea_ctx),
209	.cra_module		=	THIS_MODULE,
210	.cra_u			=	{ .cipher = {
211	.cia_min_keysize	=	TEA_KEY_SIZE,
212	.cia_max_keysize	=	TEA_KEY_SIZE,
213	.cia_setkey		= 	tea_setkey,
214	.cia_encrypt		=	tea_encrypt,
215	.cia_decrypt		=	tea_decrypt } }
216}, {
217	.cra_name		=	"xtea",
218	.cra_driver_name	=	"xtea-generic",
219	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
220	.cra_blocksize		=	XTEA_BLOCK_SIZE,
221	.cra_ctxsize		=	sizeof (struct xtea_ctx),
222	.cra_module		=	THIS_MODULE,
223	.cra_u			=	{ .cipher = {
224	.cia_min_keysize	=	XTEA_KEY_SIZE,
225	.cia_max_keysize	=	XTEA_KEY_SIZE,
226	.cia_setkey		= 	xtea_setkey,
227	.cia_encrypt		=	xtea_encrypt,
228	.cia_decrypt		=	xtea_decrypt } }
229}, {
230	.cra_name		=	"xeta",
231	.cra_driver_name	=	"xeta-generic",
232	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
233	.cra_blocksize		=	XTEA_BLOCK_SIZE,
234	.cra_ctxsize		=	sizeof (struct xtea_ctx),
235	.cra_module		=	THIS_MODULE,
236	.cra_u			=	{ .cipher = {
237	.cia_min_keysize	=	XTEA_KEY_SIZE,
238	.cia_max_keysize	=	XTEA_KEY_SIZE,
239	.cia_setkey		= 	xtea_setkey,
240	.cia_encrypt		=	xeta_encrypt,
241	.cia_decrypt		=	xeta_decrypt } }
242} };
243
244static int __init tea_mod_init(void)
245{
246	return crypto_register_algs(tea_algs, ARRAY_SIZE(tea_algs));
247}
248
249static void __exit tea_mod_fini(void)
250{
251	crypto_unregister_algs(tea_algs, ARRAY_SIZE(tea_algs));
252}
253
254MODULE_ALIAS_CRYPTO("tea");
255MODULE_ALIAS_CRYPTO("xtea");
256MODULE_ALIAS_CRYPTO("xeta");
257
258module_init(tea_mod_init);
259module_exit(tea_mod_fini);
260
261MODULE_LICENSE("GPL");
262MODULE_DESCRIPTION("TEA, XTEA & XETA Cryptographic Algorithms");