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1/*
2 * ChaCha20 256-bit cipher algorithm, RFC7539
3 *
4 * Copyright (C) 2015 Martin Willi
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
11
12#include <asm/unaligned.h>
13#include <crypto/algapi.h>
14#include <crypto/chacha20.h>
15#include <crypto/internal/skcipher.h>
16#include <linux/module.h>
17
18static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
19 unsigned int bytes)
20{
21 u32 stream[CHACHA20_BLOCK_WORDS];
22
23 if (dst != src)
24 memcpy(dst, src, bytes);
25
26 while (bytes >= CHACHA20_BLOCK_SIZE) {
27 chacha20_block(state, stream);
28 crypto_xor(dst, (const u8 *)stream, CHACHA20_BLOCK_SIZE);
29 bytes -= CHACHA20_BLOCK_SIZE;
30 dst += CHACHA20_BLOCK_SIZE;
31 }
32 if (bytes) {
33 chacha20_block(state, stream);
34 crypto_xor(dst, (const u8 *)stream, bytes);
35 }
36}
37
38void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
39{
40 state[0] = 0x61707865; /* "expa" */
41 state[1] = 0x3320646e; /* "nd 3" */
42 state[2] = 0x79622d32; /* "2-by" */
43 state[3] = 0x6b206574; /* "te k" */
44 state[4] = ctx->key[0];
45 state[5] = ctx->key[1];
46 state[6] = ctx->key[2];
47 state[7] = ctx->key[3];
48 state[8] = ctx->key[4];
49 state[9] = ctx->key[5];
50 state[10] = ctx->key[6];
51 state[11] = ctx->key[7];
52 state[12] = get_unaligned_le32(iv + 0);
53 state[13] = get_unaligned_le32(iv + 4);
54 state[14] = get_unaligned_le32(iv + 8);
55 state[15] = get_unaligned_le32(iv + 12);
56}
57EXPORT_SYMBOL_GPL(crypto_chacha20_init);
58
59int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
60 unsigned int keysize)
61{
62 struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
63 int i;
64
65 if (keysize != CHACHA20_KEY_SIZE)
66 return -EINVAL;
67
68 for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
69 ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));
70
71 return 0;
72}
73EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
74
75int crypto_chacha20_crypt(struct skcipher_request *req)
76{
77 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
78 struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
79 struct skcipher_walk walk;
80 u32 state[16];
81 int err;
82
83 err = skcipher_walk_virt(&walk, req, true);
84
85 crypto_chacha20_init(state, ctx, walk.iv);
86
87 while (walk.nbytes > 0) {
88 unsigned int nbytes = walk.nbytes;
89
90 if (nbytes < walk.total)
91 nbytes = round_down(nbytes, walk.stride);
92
93 chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
94 nbytes);
95 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
96 }
97
98 return err;
99}
100EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
101
102static struct skcipher_alg alg = {
103 .base.cra_name = "chacha20",
104 .base.cra_driver_name = "chacha20-generic",
105 .base.cra_priority = 100,
106 .base.cra_blocksize = 1,
107 .base.cra_ctxsize = sizeof(struct chacha20_ctx),
108 .base.cra_module = THIS_MODULE,
109
110 .min_keysize = CHACHA20_KEY_SIZE,
111 .max_keysize = CHACHA20_KEY_SIZE,
112 .ivsize = CHACHA20_IV_SIZE,
113 .chunksize = CHACHA20_BLOCK_SIZE,
114 .setkey = crypto_chacha20_setkey,
115 .encrypt = crypto_chacha20_crypt,
116 .decrypt = crypto_chacha20_crypt,
117};
118
119static int __init chacha20_generic_mod_init(void)
120{
121 return crypto_register_skcipher(&alg);
122}
123
124static void __exit chacha20_generic_mod_fini(void)
125{
126 crypto_unregister_skcipher(&alg);
127}
128
129module_init(chacha20_generic_mod_init);
130module_exit(chacha20_generic_mod_fini);
131
132MODULE_LICENSE("GPL");
133MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
134MODULE_DESCRIPTION("chacha20 cipher algorithm");
135MODULE_ALIAS_CRYPTO("chacha20");
136MODULE_ALIAS_CRYPTO("chacha20-generic");
1/*
2 * ChaCha20 256-bit cipher algorithm, RFC7539
3 *
4 * Copyright (C) 2015 Martin Willi
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
11
12#include <crypto/algapi.h>
13#include <linux/crypto.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <crypto/chacha20.h>
17
18static inline u32 le32_to_cpuvp(const void *p)
19{
20 return le32_to_cpup(p);
21}
22
23static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
24 unsigned int bytes)
25{
26 u8 stream[CHACHA20_BLOCK_SIZE];
27
28 if (dst != src)
29 memcpy(dst, src, bytes);
30
31 while (bytes >= CHACHA20_BLOCK_SIZE) {
32 chacha20_block(state, stream);
33 crypto_xor(dst, stream, CHACHA20_BLOCK_SIZE);
34 bytes -= CHACHA20_BLOCK_SIZE;
35 dst += CHACHA20_BLOCK_SIZE;
36 }
37 if (bytes) {
38 chacha20_block(state, stream);
39 crypto_xor(dst, stream, bytes);
40 }
41}
42
43void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
44{
45 static const char constant[16] = "expand 32-byte k";
46
47 state[0] = le32_to_cpuvp(constant + 0);
48 state[1] = le32_to_cpuvp(constant + 4);
49 state[2] = le32_to_cpuvp(constant + 8);
50 state[3] = le32_to_cpuvp(constant + 12);
51 state[4] = ctx->key[0];
52 state[5] = ctx->key[1];
53 state[6] = ctx->key[2];
54 state[7] = ctx->key[3];
55 state[8] = ctx->key[4];
56 state[9] = ctx->key[5];
57 state[10] = ctx->key[6];
58 state[11] = ctx->key[7];
59 state[12] = le32_to_cpuvp(iv + 0);
60 state[13] = le32_to_cpuvp(iv + 4);
61 state[14] = le32_to_cpuvp(iv + 8);
62 state[15] = le32_to_cpuvp(iv + 12);
63}
64EXPORT_SYMBOL_GPL(crypto_chacha20_init);
65
66int crypto_chacha20_setkey(struct crypto_tfm *tfm, const u8 *key,
67 unsigned int keysize)
68{
69 struct chacha20_ctx *ctx = crypto_tfm_ctx(tfm);
70 int i;
71
72 if (keysize != CHACHA20_KEY_SIZE)
73 return -EINVAL;
74
75 for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
76 ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));
77
78 return 0;
79}
80EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
81
82int crypto_chacha20_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
83 struct scatterlist *src, unsigned int nbytes)
84{
85 struct blkcipher_walk walk;
86 u32 state[16];
87 int err;
88
89 blkcipher_walk_init(&walk, dst, src, nbytes);
90 err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
91
92 crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
93
94 while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
95 chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
96 rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
97 err = blkcipher_walk_done(desc, &walk,
98 walk.nbytes % CHACHA20_BLOCK_SIZE);
99 }
100
101 if (walk.nbytes) {
102 chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
103 walk.nbytes);
104 err = blkcipher_walk_done(desc, &walk, 0);
105 }
106
107 return err;
108}
109EXPORT_SYMBOL_GPL(crypto_chacha20_crypt);
110
111static struct crypto_alg alg = {
112 .cra_name = "chacha20",
113 .cra_driver_name = "chacha20-generic",
114 .cra_priority = 100,
115 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
116 .cra_blocksize = 1,
117 .cra_type = &crypto_blkcipher_type,
118 .cra_ctxsize = sizeof(struct chacha20_ctx),
119 .cra_alignmask = sizeof(u32) - 1,
120 .cra_module = THIS_MODULE,
121 .cra_u = {
122 .blkcipher = {
123 .min_keysize = CHACHA20_KEY_SIZE,
124 .max_keysize = CHACHA20_KEY_SIZE,
125 .ivsize = CHACHA20_IV_SIZE,
126 .geniv = "seqiv",
127 .setkey = crypto_chacha20_setkey,
128 .encrypt = crypto_chacha20_crypt,
129 .decrypt = crypto_chacha20_crypt,
130 },
131 },
132};
133
134static int __init chacha20_generic_mod_init(void)
135{
136 return crypto_register_alg(&alg);
137}
138
139static void __exit chacha20_generic_mod_fini(void)
140{
141 crypto_unregister_alg(&alg);
142}
143
144module_init(chacha20_generic_mod_init);
145module_exit(chacha20_generic_mod_fini);
146
147MODULE_LICENSE("GPL");
148MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
149MODULE_DESCRIPTION("chacha20 cipher algorithm");
150MODULE_ALIAS_CRYPTO("chacha20");
151MODULE_ALIAS_CRYPTO("chacha20-generic");