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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539)
4 *
5 * Copyright (C) 2015 Martin Willi
6 * Copyright (C) 2018 Google LLC
7 */
8
9#include <asm/unaligned.h>
10#include <crypto/algapi.h>
11#include <crypto/chacha.h>
12#include <crypto/internal/skcipher.h>
13#include <linux/module.h>
14
15static void chacha_docrypt(u32 *state, u8 *dst, const u8 *src,
16 unsigned int bytes, int nrounds)
17{
18 /* aligned to potentially speed up crypto_xor() */
19 u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long));
20
21 while (bytes >= CHACHA_BLOCK_SIZE) {
22 chacha_block(state, stream, nrounds);
23 crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE);
24 bytes -= CHACHA_BLOCK_SIZE;
25 dst += CHACHA_BLOCK_SIZE;
26 src += CHACHA_BLOCK_SIZE;
27 }
28 if (bytes) {
29 chacha_block(state, stream, nrounds);
30 crypto_xor_cpy(dst, src, stream, bytes);
31 }
32}
33
34static int chacha_stream_xor(struct skcipher_request *req,
35 const struct chacha_ctx *ctx, const u8 *iv)
36{
37 struct skcipher_walk walk;
38 u32 state[16];
39 int err;
40
41 err = skcipher_walk_virt(&walk, req, false);
42
43 crypto_chacha_init(state, ctx, iv);
44
45 while (walk.nbytes > 0) {
46 unsigned int nbytes = walk.nbytes;
47
48 if (nbytes < walk.total)
49 nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE);
50
51 chacha_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr,
52 nbytes, ctx->nrounds);
53 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
54 }
55
56 return err;
57}
58
59void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv)
60{
61 state[0] = 0x61707865; /* "expa" */
62 state[1] = 0x3320646e; /* "nd 3" */
63 state[2] = 0x79622d32; /* "2-by" */
64 state[3] = 0x6b206574; /* "te k" */
65 state[4] = ctx->key[0];
66 state[5] = ctx->key[1];
67 state[6] = ctx->key[2];
68 state[7] = ctx->key[3];
69 state[8] = ctx->key[4];
70 state[9] = ctx->key[5];
71 state[10] = ctx->key[6];
72 state[11] = ctx->key[7];
73 state[12] = get_unaligned_le32(iv + 0);
74 state[13] = get_unaligned_le32(iv + 4);
75 state[14] = get_unaligned_le32(iv + 8);
76 state[15] = get_unaligned_le32(iv + 12);
77}
78EXPORT_SYMBOL_GPL(crypto_chacha_init);
79
80static int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key,
81 unsigned int keysize, int nrounds)
82{
83 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
84 int i;
85
86 if (keysize != CHACHA_KEY_SIZE)
87 return -EINVAL;
88
89 for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
90 ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));
91
92 ctx->nrounds = nrounds;
93 return 0;
94}
95
96int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
97 unsigned int keysize)
98{
99 return chacha_setkey(tfm, key, keysize, 20);
100}
101EXPORT_SYMBOL_GPL(crypto_chacha20_setkey);
102
103int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key,
104 unsigned int keysize)
105{
106 return chacha_setkey(tfm, key, keysize, 12);
107}
108EXPORT_SYMBOL_GPL(crypto_chacha12_setkey);
109
110int crypto_chacha_crypt(struct skcipher_request *req)
111{
112 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
113 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
114
115 return chacha_stream_xor(req, ctx, req->iv);
116}
117EXPORT_SYMBOL_GPL(crypto_chacha_crypt);
118
119int crypto_xchacha_crypt(struct skcipher_request *req)
120{
121 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
122 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
123 struct chacha_ctx subctx;
124 u32 state[16];
125 u8 real_iv[16];
126
127 /* Compute the subkey given the original key and first 128 nonce bits */
128 crypto_chacha_init(state, ctx, req->iv);
129 hchacha_block(state, subctx.key, ctx->nrounds);
130 subctx.nrounds = ctx->nrounds;
131
132 /* Build the real IV */
133 memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */
134 memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */
135
136 /* Generate the stream and XOR it with the data */
137 return chacha_stream_xor(req, &subctx, real_iv);
138}
139EXPORT_SYMBOL_GPL(crypto_xchacha_crypt);
140
141static struct skcipher_alg algs[] = {
142 {
143 .base.cra_name = "chacha20",
144 .base.cra_driver_name = "chacha20-generic",
145 .base.cra_priority = 100,
146 .base.cra_blocksize = 1,
147 .base.cra_ctxsize = sizeof(struct chacha_ctx),
148 .base.cra_module = THIS_MODULE,
149
150 .min_keysize = CHACHA_KEY_SIZE,
151 .max_keysize = CHACHA_KEY_SIZE,
152 .ivsize = CHACHA_IV_SIZE,
153 .chunksize = CHACHA_BLOCK_SIZE,
154 .setkey = crypto_chacha20_setkey,
155 .encrypt = crypto_chacha_crypt,
156 .decrypt = crypto_chacha_crypt,
157 }, {
158 .base.cra_name = "xchacha20",
159 .base.cra_driver_name = "xchacha20-generic",
160 .base.cra_priority = 100,
161 .base.cra_blocksize = 1,
162 .base.cra_ctxsize = sizeof(struct chacha_ctx),
163 .base.cra_module = THIS_MODULE,
164
165 .min_keysize = CHACHA_KEY_SIZE,
166 .max_keysize = CHACHA_KEY_SIZE,
167 .ivsize = XCHACHA_IV_SIZE,
168 .chunksize = CHACHA_BLOCK_SIZE,
169 .setkey = crypto_chacha20_setkey,
170 .encrypt = crypto_xchacha_crypt,
171 .decrypt = crypto_xchacha_crypt,
172 }, {
173 .base.cra_name = "xchacha12",
174 .base.cra_driver_name = "xchacha12-generic",
175 .base.cra_priority = 100,
176 .base.cra_blocksize = 1,
177 .base.cra_ctxsize = sizeof(struct chacha_ctx),
178 .base.cra_module = THIS_MODULE,
179
180 .min_keysize = CHACHA_KEY_SIZE,
181 .max_keysize = CHACHA_KEY_SIZE,
182 .ivsize = XCHACHA_IV_SIZE,
183 .chunksize = CHACHA_BLOCK_SIZE,
184 .setkey = crypto_chacha12_setkey,
185 .encrypt = crypto_xchacha_crypt,
186 .decrypt = crypto_xchacha_crypt,
187 }
188};
189
190static int __init chacha_generic_mod_init(void)
191{
192 return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
193}
194
195static void __exit chacha_generic_mod_fini(void)
196{
197 crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
198}
199
200subsys_initcall(chacha_generic_mod_init);
201module_exit(chacha_generic_mod_fini);
202
203MODULE_LICENSE("GPL");
204MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
205MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)");
206MODULE_ALIAS_CRYPTO("chacha20");
207MODULE_ALIAS_CRYPTO("chacha20-generic");
208MODULE_ALIAS_CRYPTO("xchacha20");
209MODULE_ALIAS_CRYPTO("xchacha20-generic");
210MODULE_ALIAS_CRYPTO("xchacha12");
211MODULE_ALIAS_CRYPTO("xchacha12-generic");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539)
4 *
5 * Copyright (C) 2015 Martin Willi
6 * Copyright (C) 2018 Google LLC
7 */
8
9#include <asm/unaligned.h>
10#include <crypto/algapi.h>
11#include <crypto/internal/chacha.h>
12#include <crypto/internal/skcipher.h>
13#include <linux/module.h>
14
15static int chacha_stream_xor(struct skcipher_request *req,
16 const struct chacha_ctx *ctx, const u8 *iv)
17{
18 struct skcipher_walk walk;
19 u32 state[16];
20 int err;
21
22 err = skcipher_walk_virt(&walk, req, false);
23
24 chacha_init_generic(state, ctx->key, iv);
25
26 while (walk.nbytes > 0) {
27 unsigned int nbytes = walk.nbytes;
28
29 if (nbytes < walk.total)
30 nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE);
31
32 chacha_crypt_generic(state, walk.dst.virt.addr,
33 walk.src.virt.addr, nbytes, ctx->nrounds);
34 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
35 }
36
37 return err;
38}
39
40static int crypto_chacha_crypt(struct skcipher_request *req)
41{
42 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
43 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
44
45 return chacha_stream_xor(req, ctx, req->iv);
46}
47
48static int crypto_xchacha_crypt(struct skcipher_request *req)
49{
50 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
51 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
52 struct chacha_ctx subctx;
53 u32 state[16];
54 u8 real_iv[16];
55
56 /* Compute the subkey given the original key and first 128 nonce bits */
57 chacha_init_generic(state, ctx->key, req->iv);
58 hchacha_block_generic(state, subctx.key, ctx->nrounds);
59 subctx.nrounds = ctx->nrounds;
60
61 /* Build the real IV */
62 memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */
63 memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */
64
65 /* Generate the stream and XOR it with the data */
66 return chacha_stream_xor(req, &subctx, real_iv);
67}
68
69static struct skcipher_alg algs[] = {
70 {
71 .base.cra_name = "chacha20",
72 .base.cra_driver_name = "chacha20-generic",
73 .base.cra_priority = 100,
74 .base.cra_blocksize = 1,
75 .base.cra_ctxsize = sizeof(struct chacha_ctx),
76 .base.cra_module = THIS_MODULE,
77
78 .min_keysize = CHACHA_KEY_SIZE,
79 .max_keysize = CHACHA_KEY_SIZE,
80 .ivsize = CHACHA_IV_SIZE,
81 .chunksize = CHACHA_BLOCK_SIZE,
82 .setkey = chacha20_setkey,
83 .encrypt = crypto_chacha_crypt,
84 .decrypt = crypto_chacha_crypt,
85 }, {
86 .base.cra_name = "xchacha20",
87 .base.cra_driver_name = "xchacha20-generic",
88 .base.cra_priority = 100,
89 .base.cra_blocksize = 1,
90 .base.cra_ctxsize = sizeof(struct chacha_ctx),
91 .base.cra_module = THIS_MODULE,
92
93 .min_keysize = CHACHA_KEY_SIZE,
94 .max_keysize = CHACHA_KEY_SIZE,
95 .ivsize = XCHACHA_IV_SIZE,
96 .chunksize = CHACHA_BLOCK_SIZE,
97 .setkey = chacha20_setkey,
98 .encrypt = crypto_xchacha_crypt,
99 .decrypt = crypto_xchacha_crypt,
100 }, {
101 .base.cra_name = "xchacha12",
102 .base.cra_driver_name = "xchacha12-generic",
103 .base.cra_priority = 100,
104 .base.cra_blocksize = 1,
105 .base.cra_ctxsize = sizeof(struct chacha_ctx),
106 .base.cra_module = THIS_MODULE,
107
108 .min_keysize = CHACHA_KEY_SIZE,
109 .max_keysize = CHACHA_KEY_SIZE,
110 .ivsize = XCHACHA_IV_SIZE,
111 .chunksize = CHACHA_BLOCK_SIZE,
112 .setkey = chacha12_setkey,
113 .encrypt = crypto_xchacha_crypt,
114 .decrypt = crypto_xchacha_crypt,
115 }
116};
117
118static int __init chacha_generic_mod_init(void)
119{
120 return crypto_register_skciphers(algs, ARRAY_SIZE(algs));
121}
122
123static void __exit chacha_generic_mod_fini(void)
124{
125 crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
126}
127
128subsys_initcall(chacha_generic_mod_init);
129module_exit(chacha_generic_mod_fini);
130
131MODULE_LICENSE("GPL");
132MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
133MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)");
134MODULE_ALIAS_CRYPTO("chacha20");
135MODULE_ALIAS_CRYPTO("chacha20-generic");
136MODULE_ALIAS_CRYPTO("xchacha20");
137MODULE_ALIAS_CRYPTO("xchacha20-generic");
138MODULE_ALIAS_CRYPTO("xchacha12");
139MODULE_ALIAS_CRYPTO("xchacha12-generic");