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 * Also modified to set up the initial state using the generic C code rather
15 * than in assembly.
16 *
17 * This program is free software; you can redistribute it and/or modify it
18 * under the terms of the GNU General Public License as published by the Free
19 * Software Foundation; either version 2 of the License, or (at your option)
20 * any later version.
21 *
22 */
23
24 #include <asm/unaligned.h>
25 #include <crypto/internal/skcipher.h>
26 #include <crypto/salsa20.h>
27 #include <linux/module.h>
28
29 asmlinkage void salsa20_encrypt_bytes(u32 state[16], const u8 *src, u8 *dst,
30 u32 bytes);
31
32 static int salsa20_asm_crypt(struct skcipher_request *req)
33 {
34 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
35 const struct salsa20_ctx *ctx = crypto_skcipher_ctx(tfm);
36 struct skcipher_walk walk;
37 u32 state[16];
38 int err;
39
40 err = skcipher_walk_virt(&walk, req, true);
41
42 crypto_salsa20_init(state, ctx, walk.iv);
43
44 while (walk.nbytes > 0) {
45 unsigned int nbytes = walk.nbytes;
46
47 if (nbytes < walk.total)
48 nbytes = round_down(nbytes, walk.stride);
49
50 salsa20_encrypt_bytes(state, walk.src.virt.addr,
51 walk.dst.virt.addr, nbytes);
52 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
53 }
54
55 return err;
56 }
57
58 static struct skcipher_alg alg = {
59 .base.cra_name = "salsa20",
60 .base.cra_driver_name = "salsa20-asm",
61 .base.cra_priority = 200,
62 .base.cra_blocksize = 1,
63 .base.cra_ctxsize = sizeof(struct salsa20_ctx),
64 .base.cra_module = THIS_MODULE,
65
66 .min_keysize = SALSA20_MIN_KEY_SIZE,
67 .max_keysize = SALSA20_MAX_KEY_SIZE,
68 .ivsize = SALSA20_IV_SIZE,
69 .chunksize = SALSA20_BLOCK_SIZE,
70 .setkey = crypto_salsa20_setkey,
71 .encrypt = salsa20_asm_crypt,
72 .decrypt = salsa20_asm_crypt,
73 };
74
75 static int __init init(void)
76 {
77 return crypto_register_skcipher(&alg);
78 }
79
80 static void __exit fini(void)
81 {
82 crypto_unregister_skcipher(&alg);
83 }
84
85 module_init(init);
86 module_exit(fini);
87
88 MODULE_LICENSE("GPL");
89 MODULE_DESCRIPTION ("Salsa20 stream cipher algorithm (optimized assembly version)");
90 MODULE_ALIAS_CRYPTO("salsa20");
91 MODULE_ALIAS_CRYPTO("salsa20-asm");
92
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