Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/crypto/salsa20_generic.c

  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 <linux/bitops.h>
 28 #include <crypto/algapi.h>
 29 #include <asm/byteorder.h>
 30 
 31 #define SALSA20_IV_SIZE        8U
 32 #define SALSA20_MIN_KEY_SIZE  16U
 33 #define SALSA20_MAX_KEY_SIZE  32U
 34 
 35 /*
 36  * Start of code taken from D. J. Bernstein's reference implementation.
 37  * With some modifications and optimizations made to suit our needs.
 38  */
 39 
 40 /*
 41 salsa20-ref.c version 20051118
 42 D. J. Bernstein
 43 Public domain.
 44 */
 45 
 46 #define U32TO8_LITTLE(p, v) \
 47         { (p)[0] = (v >>  0) & 0xff; (p)[1] = (v >>  8) & 0xff; \
 48           (p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
 49 #define U8TO32_LITTLE(p)   \
 50         (((u32)((p)[0])      ) | ((u32)((p)[1]) <<  8) | \
 51          ((u32)((p)[2]) << 16) | ((u32)((p)[3]) << 24)   )
 52 
 53 struct salsa20_ctx
 54 {
 55         u32 input[16];
 56 };
 57 
 58 static void salsa20_wordtobyte(u8 output[64], const u32 input[16])
 59 {
 60         u32 x[16];
 61         int i;
 62 
 63         memcpy(x, input, sizeof(x));
 64         for (i = 20; i > 0; i -= 2) {
 65                 x[ 4] ^= rol32((x[ 0] + x[12]),  7);
 66                 x[ 8] ^= rol32((x[ 4] + x[ 0]),  9);
 67                 x[12] ^= rol32((x[ 8] + x[ 4]), 13);
 68                 x[ 0] ^= rol32((x[12] + x[ 8]), 18);
 69                 x[ 9] ^= rol32((x[ 5] + x[ 1]),  7);
 70                 x[13] ^= rol32((x[ 9] + x[ 5]),  9);
 71                 x[ 1] ^= rol32((x[13] + x[ 9]), 13);
 72                 x[ 5] ^= rol32((x[ 1] + x[13]), 18);
 73                 x[14] ^= rol32((x[10] + x[ 6]),  7);
 74                 x[ 2] ^= rol32((x[14] + x[10]),  9);
 75                 x[ 6] ^= rol32((x[ 2] + x[14]), 13);
 76                 x[10] ^= rol32((x[ 6] + x[ 2]), 18);
 77                 x[ 3] ^= rol32((x[15] + x[11]),  7);
 78                 x[ 7] ^= rol32((x[ 3] + x[15]),  9);
 79                 x[11] ^= rol32((x[ 7] + x[ 3]), 13);
 80                 x[15] ^= rol32((x[11] + x[ 7]), 18);
 81                 x[ 1] ^= rol32((x[ 0] + x[ 3]),  7);
 82                 x[ 2] ^= rol32((x[ 1] + x[ 0]),  9);
 83                 x[ 3] ^= rol32((x[ 2] + x[ 1]), 13);
 84                 x[ 0] ^= rol32((x[ 3] + x[ 2]), 18);
 85                 x[ 6] ^= rol32((x[ 5] + x[ 4]),  7);
 86                 x[ 7] ^= rol32((x[ 6] + x[ 5]),  9);
 87                 x[ 4] ^= rol32((x[ 7] + x[ 6]), 13);
 88                 x[ 5] ^= rol32((x[ 4] + x[ 7]), 18);
 89                 x[11] ^= rol32((x[10] + x[ 9]),  7);
 90                 x[ 8] ^= rol32((x[11] + x[10]),  9);
 91                 x[ 9] ^= rol32((x[ 8] + x[11]), 13);
 92                 x[10] ^= rol32((x[ 9] + x[ 8]), 18);
 93                 x[12] ^= rol32((x[15] + x[14]),  7);
 94                 x[13] ^= rol32((x[12] + x[15]),  9);
 95                 x[14] ^= rol32((x[13] + x[12]), 13);
 96                 x[15] ^= rol32((x[14] + x[13]), 18);
 97         }
 98         for (i = 0; i < 16; ++i)
 99                 x[i] += input[i];
100         for (i = 0; i < 16; ++i)
101                 U32TO8_LITTLE(output + 4 * i,x[i]);
102 }
103 
104 static const char sigma[16] = "expand 32-byte k";
105 static const char tau[16] = "expand 16-byte k";
106 
107 static void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k, u32 kbytes)
108 {
109         const char *constants;
110 
111         ctx->input[1] = U8TO32_LITTLE(k + 0);
112         ctx->input[2] = U8TO32_LITTLE(k + 4);
113         ctx->input[3] = U8TO32_LITTLE(k + 8);
114         ctx->input[4] = U8TO32_LITTLE(k + 12);
115         if (kbytes == 32) { /* recommended */
116                 k += 16;
117                 constants = sigma;
118         } else { /* kbytes == 16 */
119                 constants = tau;
120         }
121         ctx->input[11] = U8TO32_LITTLE(k + 0);
122         ctx->input[12] = U8TO32_LITTLE(k + 4);
123         ctx->input[13] = U8TO32_LITTLE(k + 8);
124         ctx->input[14] = U8TO32_LITTLE(k + 12);
125         ctx->input[0] = U8TO32_LITTLE(constants + 0);
126         ctx->input[5] = U8TO32_LITTLE(constants + 4);
127         ctx->input[10] = U8TO32_LITTLE(constants + 8);
128         ctx->input[15] = U8TO32_LITTLE(constants + 12);
129 }
130 
131 static void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv)
132 {
133         ctx->input[6] = U8TO32_LITTLE(iv + 0);
134         ctx->input[7] = U8TO32_LITTLE(iv + 4);
135         ctx->input[8] = 0;
136         ctx->input[9] = 0;
137 }
138 
139 static void salsa20_encrypt_bytes(struct salsa20_ctx *ctx, u8 *dst,
140                                   const u8 *src, unsigned int bytes)
141 {
142         u8 buf[64];
143 
144         if (dst != src)
145                 memcpy(dst, src, bytes);
146 
147         while (bytes) {
148                 salsa20_wordtobyte(buf, ctx->input);
149 
150                 ctx->input[8]++;
151                 if (!ctx->input[8])
152                         ctx->input[9]++;
153 
154                 if (bytes <= 64) {
155                         crypto_xor(dst, buf, bytes);
156                         return;
157                 }
158 
159                 crypto_xor(dst, buf, 64);
160                 bytes -= 64;
161                 dst += 64;
162         }
163 }
164 
165 /*
166  * End of code taken from D. J. Bernstein's reference implementation.
167  */
168 
169 static int setkey(struct crypto_tfm *tfm, const u8 *key,
170                   unsigned int keysize)
171 {
172         struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
173         salsa20_keysetup(ctx, key, keysize);
174         return 0;
175 }
176 
177 static int encrypt(struct blkcipher_desc *desc,
178                    struct scatterlist *dst, struct scatterlist *src,
179                    unsigned int nbytes)
180 {
181         struct blkcipher_walk walk;
182         struct crypto_blkcipher *tfm = desc->tfm;
183         struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
184         int err;
185 
186         blkcipher_walk_init(&walk, dst, src, nbytes);
187         err = blkcipher_walk_virt_block(desc, &walk, 64);
188 
189         salsa20_ivsetup(ctx, walk.iv);
190 
191         if (likely(walk.nbytes == nbytes))
192         {
193                 salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
194                                       walk.src.virt.addr, nbytes);
195                 return blkcipher_walk_done(desc, &walk, 0);
196         }
197 
198         while (walk.nbytes >= 64) {
199                 salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
200                                       walk.src.virt.addr,
201                                       walk.nbytes - (walk.nbytes % 64));
202                 err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
203         }
204 
205         if (walk.nbytes) {
206                 salsa20_encrypt_bytes(ctx, walk.dst.virt.addr,
207                                       walk.src.virt.addr, walk.nbytes);
208                 err = blkcipher_walk_done(desc, &walk, 0);
209         }
210 
211         return err;
212 }
213 
214 static struct crypto_alg alg = {
215         .cra_name           =   "salsa20",
216         .cra_driver_name    =   "salsa20-generic",
217         .cra_priority       =   100,
218         .cra_flags          =   CRYPTO_ALG_TYPE_BLKCIPHER,
219         .cra_type           =   &crypto_blkcipher_type,
220         .cra_blocksize      =   1,
221         .cra_ctxsize        =   sizeof(struct salsa20_ctx),
222         .cra_alignmask      =   3,
223         .cra_module         =   THIS_MODULE,
224         .cra_u              =   {
225                 .blkcipher = {
226                         .setkey         =   setkey,
227                         .encrypt        =   encrypt,
228                         .decrypt        =   encrypt,
229                         .min_keysize    =   SALSA20_MIN_KEY_SIZE,
230                         .max_keysize    =   SALSA20_MAX_KEY_SIZE,
231                         .ivsize         =   SALSA20_IV_SIZE,
232                 }
233         }
234 };
235 
236 static int __init salsa20_generic_mod_init(void)
237 {
238         return crypto_register_alg(&alg);
239 }
240 
241 static void __exit salsa20_generic_mod_fini(void)
242 {
243         crypto_unregister_alg(&alg);
244 }
245 
246 module_init(salsa20_generic_mod_init);
247 module_exit(salsa20_generic_mod_fini);
248 
249 MODULE_LICENSE("GPL");
250 MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm");
251 MODULE_ALIAS_CRYPTO("salsa20");
252 MODULE_ALIAS_CRYPTO("salsa20-generic");
253 

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us