1 /*
2 * Glue code for optimized assembly version of Salsa20.
3 *
4 * Copyright (c) 2007 Tan Swee Heng <thesweeheng@gmail.com>
5 *
6 * The assembly codes are public domain assembly codes written by Daniel. J.
7 * Bernstein <djb@cr.yp.to>. The codes are modified to include indentation
8 * and to remove extraneous comments and functions that are not needed.
9 * - i586 version, renamed as salsa20-i586-asm_32.S
10 * available from <http://cr.yp.to/snuffle/salsa20/x86-pm/salsa20.s>
11 * - x86-64 version, renamed as salsa20-x86_64-asm_64.S
12 * available from <http://cr.yp.to/snuffle/salsa20/amd64-3/salsa20.s>
13 *
14 * This program is free software; you can redistribute it and/or modify it
15 * under the terms of the GNU General Public License as published by the Free
16 * Software Foundation; either version 2 of the License, or (at your option)
17 * any later version.
18 *
19 */
20
21 #include <crypto/algapi.h>
22 #include <linux/module.h>
23 #include <linux/crypto.h>
24
25 #define SALSA20_IV_SIZE 8U
26 #define SALSA20_MIN_KEY_SIZE 16U
27 #define SALSA20_MAX_KEY_SIZE 32U
28
29 struct salsa20_ctx
30 {
31 u32 input[16];
32 };
33
34 asmlinkage void salsa20_keysetup(struct salsa20_ctx *ctx, const u8 *k,
35 u32 keysize, u32 ivsize);
36 asmlinkage void salsa20_ivsetup(struct salsa20_ctx *ctx, const u8 *iv);
37 asmlinkage void salsa20_encrypt_bytes(struct salsa20_ctx *ctx,
38 const u8 *src, u8 *dst, u32 bytes);
39
setkey(struct crypto_tfm * tfm,const u8 * key,unsigned int keysize)40 static int setkey(struct crypto_tfm *tfm, const u8 *key,
41 unsigned int keysize)
42 {
43 struct salsa20_ctx *ctx = crypto_tfm_ctx(tfm);
44 salsa20_keysetup(ctx, key, keysize*8, SALSA20_IV_SIZE*8);
45 return 0;
46 }
47
encrypt(struct blkcipher_desc * desc,struct scatterlist * dst,struct scatterlist * src,unsigned int nbytes)48 static int encrypt(struct blkcipher_desc *desc,
49 struct scatterlist *dst, struct scatterlist *src,
50 unsigned int nbytes)
51 {
52 struct blkcipher_walk walk;
53 struct crypto_blkcipher *tfm = desc->tfm;
54 struct salsa20_ctx *ctx = crypto_blkcipher_ctx(tfm);
55 int err;
56
57 blkcipher_walk_init(&walk, dst, src, nbytes);
58 err = blkcipher_walk_virt_block(desc, &walk, 64);
59
60 salsa20_ivsetup(ctx, walk.iv);
61
62 if (likely(walk.nbytes == nbytes))
63 {
64 salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
65 walk.dst.virt.addr, nbytes);
66 return blkcipher_walk_done(desc, &walk, 0);
67 }
68
69 while (walk.nbytes >= 64) {
70 salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
71 walk.dst.virt.addr,
72 walk.nbytes - (walk.nbytes % 64));
73 err = blkcipher_walk_done(desc, &walk, walk.nbytes % 64);
74 }
75
76 if (walk.nbytes) {
77 salsa20_encrypt_bytes(ctx, walk.src.virt.addr,
78 walk.dst.virt.addr, walk.nbytes);
79 err = blkcipher_walk_done(desc, &walk, 0);
80 }
81
82 return err;
83 }
84
85 static struct crypto_alg alg = {
86 .cra_name = "salsa20",
87 .cra_driver_name = "salsa20-asm",
88 .cra_priority = 200,
89 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
90 .cra_type = &crypto_blkcipher_type,
91 .cra_blocksize = 1,
92 .cra_ctxsize = sizeof(struct salsa20_ctx),
93 .cra_alignmask = 3,
94 .cra_module = THIS_MODULE,
95 .cra_u = {
96 .blkcipher = {
97 .setkey = setkey,
98 .encrypt = encrypt,
99 .decrypt = encrypt,
100 .min_keysize = SALSA20_MIN_KEY_SIZE,
101 .max_keysize = SALSA20_MAX_KEY_SIZE,
102 .ivsize = SALSA20_IV_SIZE,
103 }
104 }
105 };
106
init(void)107 static int __init init(void)
108 {
109 return crypto_register_alg(&alg);
110 }
111
fini(void)112 static void __exit fini(void)
113 {
114 crypto_unregister_alg(&alg);
115 }
116
117 module_init(init);
118 module_exit(fini);
119
120 MODULE_LICENSE("GPL");
121 MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
122 MODULE_ALIAS("salsa20");
123 MODULE_ALIAS("salsa20-asm");
124