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authorTan Swee Heng <thesweeheng@gmail.com>2007-11-23 06:45:00 -0500
committerHerbert Xu <herbert@gondor.apana.org.au>2008-01-10 16:16:15 -0500
commit2407d60872dd2a95404c6048f775f3b64d438f4b (patch)
tree6a333c5eaae616736b2f184cee8e9f052cee966d /crypto/salsa20_generic.c
parent332f8840f7095d294f9bb066b175a100bcde214c (diff)
[CRYPTO] salsa20: Salsa20 stream cipher
This patch implements the Salsa20 stream cipher using the blkcipher interface. The core cipher code comes from Daniel Bernstein's submission to eSTREAM: http://www.ecrypt.eu.org/stream/svn/viewcvs.cgi/ecrypt/trunk/submissions/salsa20/full/ref/ The test vectors comes from: http://www.ecrypt.eu.org/stream/svn/viewcvs.cgi/ecrypt/trunk/submissions/salsa20/full/ It has been tested successfully with "modprobe tcrypt mode=34" on an UML instance. Signed-off-by: Tan Swee Heng <thesweeheng@gmail.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/salsa20_generic.c')
-rw-r--r--crypto/salsa20_generic.c243
1 files changed, 243 insertions, 0 deletions
diff --git a/crypto/salsa20_generic.c b/crypto/salsa20_generic.c
new file mode 100644
index 000000000000..b49328afcf0a
--- /dev/null
+++ b/crypto/salsa20_generic.c
@@ -0,0 +1,243 @@
1/*
2 * Salsa20: Salsa20 stream cipher algorithm
3 *
4 * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
5 *
6 * Derived from:
7 * - salsa20.c: Public domain C code by Daniel J. Bernstein <djb@cr.yp.to>
8 *
9 * Salsa20 is a stream cipher candidate in eSTREAM, the ECRYPT Stream
10 * Cipher Project. It is designed by Daniel J. Bernstein <djb@cr.yp.to>.
11 * More information about eSTREAM and Salsa20 can be found here:
12 * http://www.ecrypt.eu.org/stream/
13 * http://cr.yp.to/snuffle.html
14 *
15 * This program is free software; you can redistribute it and/or modify it
16 * under the terms of the GNU General Public License as published by the Free
17 * Software Foundation; either version 2 of the License, or (at your option)
18 * any later version.
19 *
20 */
21
22#include <linux/init.h>
23#include <linux/module.h>
24#include <linux/errno.h>
25#include <linux/crypto.h>
26#include <linux/types.h>
27#include <crypto/algapi.h>
28#include <asm/byteorder.h>
29
30#define SALSA20_IV_SIZE 8U
31#define SALSA20_MIN_KEY_SIZE 16U
32#define SALSA20_MAX_KEY_SIZE 32U
33
34/*
35 * Start of code taken from D. J. Bernstein's reference implementation.
36 * With some modifications and optimizations made to suit our needs.
37 */
38
39/*
40salsa20-ref.c version 20051118
41D. J. Bernstein
42Public domain.
43*/
44
45#define ROTATE(v,n) (((v) << (n)) | ((v) >> (32 - (n))))
46#define XOR(v,w) ((v) ^ (w))
47#define PLUS(v,w) (((v) + (w)))
48#define PLUSONE(v) (PLUS((v),1))
49#define U32TO8_LITTLE(p, v) \
50 { (p)[0] = (v >> 0) & 0xff; (p)[1] = (v >> 8) & 0xff; \
51 (p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
52#define U8TO32_LITTLE(p) \
53 (((u32)((p)[0]) ) | ((u32)((p)[1]) << 8) | \
54 ((u32)((p)[2]) << 16) | ((u32)((p)[3]) << 24) )
55
56struct salsa20_ctx
57{
58 u32 input[16];
59};
60
61static void salsa20_wordtobyte(u8 output[64], const u32 input[16])
62{
63 u32 x[16];
64 int i;
65
66 memcpy(x, input, sizeof(x));
67 for (i = 20; i > 0; i -= 2) {
68 x[ 4] = XOR(x[ 4],ROTATE(PLUS(x[ 0],x[12]), 7));
69 x[ 8] = XOR(x[ 8],ROTATE(PLUS(x[ 4],x[ 0]), 9));
70 x[12] = XOR(x[12],ROTATE(PLUS(x[ 8],x[ 4]),13));
71 x[ 0] = XOR(x[ 0],ROTATE(PLUS(x[12],x[ 8]),18));
72 x[ 9] = XOR(x[ 9],ROTATE(PLUS(x[ 5],x[ 1]), 7));
73 x[13] = XOR(x[13],ROTATE(PLUS(x[ 9],x[ 5]), 9));
74 x[ 1] = XOR(x[ 1],ROTATE(PLUS(x[13],x[ 9]),13));
75 x[ 5] = XOR(x[ 5],ROTATE(PLUS(x[ 1],x[13]),18));
76 x[14] = XOR(x[14],ROTATE(PLUS(x[10],x[ 6]), 7));
77 x[ 2] = XOR(x[ 2],ROTATE(PLUS(x[14],x[10]), 9));
78 x[ 6] = XOR(x[ 6],ROTATE(PLUS(x[ 2],x[14]),13));
79 x[10] = XOR(x[10],ROTATE(PLUS(x[ 6],x[ 2]),18));
80 x[ 3] = XOR(x[ 3],ROTATE(PLUS(x[15],x[11]), 7));
81 x[ 7] = XOR(x[ 7],ROTATE(PLUS(x[ 3],x[15]), 9));
82 x[11] = XOR(x[11],ROTATE(PLUS(x[ 7],x[ 3]),13));
83 x[15] = XOR(x[15],ROTATE(PLUS(x[11],x[ 7]),18));
84 x[ 1] = XOR(x[ 1],ROTATE(PLUS(x[ 0],x[ 3]), 7));
85 x[ 2] = XOR(x[ 2],ROTATE(PLUS(x[ 1],x[ 0]), 9));
86 x[ 3] = XOR(x[ 3],ROTATE(PLUS(x[ 2],x[ 1]),13));
87 x[ 0] = XOR(x[ 0],ROTATE(PLUS(x[ 3],x[ 2]),18));
88 x[ 6] = XOR(x[ 6],ROTATE(PLUS(x[ 5],x[ 4]), 7));
89 x[ 7] = XOR(x[ 7],ROTATE(PLUS(x[ 6],x[ 5]), 9));
90 x[ 4] = XOR(x[ 4],ROTATE(PLUS(x[ 7],x[ 6]),13));
91 x[ 5] = XOR(x[ 5],ROTATE(PLUS(x[ 4],x[ 7]),18));
92 x[11] = XOR(x[11],ROTATE(PLUS(x[10],x[ 9]), 7));
93 x[ 8] = XOR(x[ 8],ROTATE(PLUS(x[11],x[10]), 9));
94 x[ 9] = XOR(x[ 9],ROTATE(PLUS(x[ 8],x[11]),13));
95 x[10] = XOR(x[10],ROTATE(PLUS(x[ 9],x[ 8]),18));
96 x[12] = XOR(x[12],ROTATE(PLUS(x[15],x[14]), 7));
97 x[13] = XOR(x[13],ROTATE(PLUS(x[12],x[15]), 9));
98 x[14] = XOR(x[14],ROTATE(PLUS(x[13],x[12]),13));
99 x[15] = XOR(x[15],ROTATE(PLUS(x[14],x[13]),18));
100 }
101 for (i = 0; i < 16; ++i)
102 x[i] = PLUS(x[i],input[i]);
103 for (i = 0; i < 16; ++i)
104 U32TO8_LITTLE(output + 4 * i,x[i]);
105}
106
107static const char sigma[16] = "expand 32-byte k";
108static const char tau[16] = "expand 16-byte k";
109
110static void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k, u32 kbytes)
111{
112 const char *constants;
113
114 ctx->input[1] = U8TO32_LITTLE(k + 0);
115 ctx->input[2] = U8TO32_LITTLE(k + 4);
116 ctx->input[3] = U8TO32_LITTLE(k + 8);
117 ctx->input[4] = U8TO32_LITTLE(k + 12);
118 if (kbytes == 32) { /* recommended */
119 k += 16;
120 constants = sigma;
121 } else { /* kbytes == 16 */
122 constants = tau;
123 }
124 ctx->input[11] = U8TO32_LITTLE(k + 0);
125 ctx->input[12] = U8TO32_LITTLE(k + 4);
126 ctx->input[13] = U8TO32_LITTLE(k + 8);
127 ctx->input[14] = U8TO32_LITTLE(k + 12);
128 ctx->input[0] = U8TO32_LITTLE(constants + 0);
129 ctx->input[5] = U8TO32_LITTLE(constants + 4);
130 ctx->input[10] = U8TO32_LITTLE(constants + 8);
131 ctx->input[15] = U8TO32_LITTLE(constants + 12);
132}
133
134static void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv)
135{
136 ctx->input[6] = U8TO32_LITTLE(iv + 0);
137 ctx->input[7] = U8TO32_LITTLE(iv + 4);
138 ctx->input[8] = 0;
139 ctx->input[9] = 0;
140}
141
142static void salsa20_encrypt_bytes(struct salsa20_ctx *ctx, u8 *dst,
143 const u8 *src, unsigned int bytes)
144{
145 u8 buf[64];
146 int i;
147
148 if (dst != src)
149 memcpy(dst, src, bytes);
150
151 while (bytes) {
152 salsa20_wordtobyte(buf, ctx->input);
153
154 ctx->input[8] = PLUSONE(ctx->input[8]);
155 if (!ctx->input[8])
156 ctx->input[9] = PLUSONE(ctx->input[9]);
157
158 if (bytes <= 64) {
159 for (i = 0; i < bytes/4; ++i)
160 ((u32*)dst)[i] ^= ((u32*)buf)[i];
161 for (i = bytes - bytes % 4; i < bytes; ++i)
162 dst[i] ^= buf[i];
163 return;
164 }
165
166 for (i = 0; i < 64/4; ++i)
167 ((u32*)dst)[i] ^= ((u32*)buf)[i];
168 bytes -= 64;
169 dst += 64;
170 }
171}
172
173/*
174 * End of code taken from D. J. Bernstein's reference implementation.
175 */
176
177static int setkey(struct crypto_tfm *tfm, const u8 *key,
178 unsigned int keysize)
179{
180 struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
181 salsa20_keysetup(ctx, key, keysize);
182 return 0;
183}
184
185static int encrypt(struct blkcipher_desc *desc,
186 struct scatterlist *dst, struct scatterlist *src,
187 unsigned int nbytes)
188{
189 struct blkcipher_walk walk;
190 struct crypto_blkcipher *tfm = desc->tfm;
191 struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
192 int err;
193
194 blkcipher_walk_init(&walk, dst, src, nbytes);
195 err = blkcipher_walk_virt(desc, &walk);
196
197 salsa20_ivsetup(ctx, walk.iv);
198 salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
199 walk.src.virt.addr, nbytes);
200
201 err = blkcipher_walk_done(desc, &walk, 0);
202 return err;
203}
204
205static struct crypto_alg alg = {
206 .cra_name = "salsa20",
207 .cra_driver_name = "salsa20-generic",
208 .cra_priority = 100,
209 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
210 .cra_type = &crypto_blkcipher_type,
211 .cra_blocksize = 1,
212 .cra_ctxsize = sizeof(struct salsa20_ctx),
213 .cra_alignmask = 3,
214 .cra_module = THIS_MODULE,
215 .cra_list = LIST_HEAD_INIT(alg.cra_list),
216 .cra_u = {
217 .blkcipher = {
218 .setkey = setkey,
219 .encrypt = encrypt,
220 .decrypt = encrypt,
221 .min_keysize = SALSA20_MIN_KEY_SIZE,
222 .max_keysize = SALSA20_MAX_KEY_SIZE,
223 .ivsize = SALSA20_IV_SIZE,
224 }
225 }
226};
227
228static int __init init(void)
229{
230 return crypto_register_alg(&alg);
231}
232
233static void __exit fini(void)
234{
235 crypto_unregister_alg(&alg);
236}
237
238module_init(init);
239module_exit(fini);
240
241MODULE_LICENSE("GPL");
242MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
243MODULE_ALIAS("salsa20");