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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
c08d0e64 | 2 | /* |
aa762409 | 3 | * ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539) |
c08d0e64 MW |
4 | * |
5 | * Copyright (C) 2015 Martin Willi | |
de61d7ae | 6 | * Copyright (C) 2018 Google LLC |
c08d0e64 MW |
7 | */ |
8 | ||
dbd872a1 | 9 | #include <asm/unaligned.h> |
c08d0e64 | 10 | #include <crypto/algapi.h> |
1ca1b917 | 11 | #include <crypto/chacha.h> |
9ae433bc AB |
12 | #include <crypto/internal/skcipher.h> |
13 | #include <linux/module.h> | |
c08d0e64 | 14 | |
1ca1b917 EB |
15 | static void chacha_docrypt(u32 *state, u8 *dst, const u8 *src, |
16 | unsigned int bytes, int nrounds) | |
c08d0e64 | 17 | { |
a5e9f557 | 18 | /* aligned to potentially speed up crypto_xor() */ |
1ca1b917 | 19 | u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long)); |
c08d0e64 | 20 | |
1ca1b917 EB |
21 | while (bytes >= CHACHA_BLOCK_SIZE) { |
22 | chacha_block(state, stream, nrounds); | |
29d97dec | 23 | crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE); |
1ca1b917 EB |
24 | bytes -= CHACHA_BLOCK_SIZE; |
25 | dst += CHACHA_BLOCK_SIZE; | |
29d97dec | 26 | src += CHACHA_BLOCK_SIZE; |
c08d0e64 MW |
27 | } |
28 | if (bytes) { | |
1ca1b917 | 29 | chacha_block(state, stream, nrounds); |
29d97dec | 30 | crypto_xor_cpy(dst, src, stream, bytes); |
c08d0e64 MW |
31 | } |
32 | } | |
33 | ||
1ca1b917 | 34 | static int chacha_stream_xor(struct skcipher_request *req, |
860ab2e5 | 35 | const struct chacha_ctx *ctx, const u8 *iv) |
de61d7ae EB |
36 | { |
37 | struct skcipher_walk walk; | |
38 | u32 state[16]; | |
39 | int err; | |
40 | ||
41 | err = skcipher_walk_virt(&walk, req, false); | |
42 | ||
1ca1b917 | 43 | crypto_chacha_init(state, ctx, iv); |
de61d7ae EB |
44 | |
45 | while (walk.nbytes > 0) { | |
46 | unsigned int nbytes = walk.nbytes; | |
47 | ||
48 | if (nbytes < walk.total) | |
7aceaaef | 49 | nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE); |
de61d7ae | 50 | |
1ca1b917 EB |
51 | chacha_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, |
52 | nbytes, ctx->nrounds); | |
de61d7ae EB |
53 | err = skcipher_walk_done(&walk, walk.nbytes - nbytes); |
54 | } | |
55 | ||
56 | return err; | |
57 | } | |
58 | ||
860ab2e5 | 59 | void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv) |
c08d0e64 | 60 | { |
ecf3220d EB |
61 | state[0] = 0x61707865; /* "expa" */ |
62 | state[1] = 0x3320646e; /* "nd 3" */ | |
63 | state[2] = 0x79622d32; /* "2-by" */ | |
64 | state[3] = 0x6b206574; /* "te k" */ | |
c08d0e64 MW |
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]; | |
dbd872a1 EB |
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); | |
c08d0e64 | 77 | } |
1ca1b917 | 78 | EXPORT_SYMBOL_GPL(crypto_chacha_init); |
c08d0e64 | 79 | |
1ca1b917 EB |
80 | static int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key, |
81 | unsigned int keysize, int nrounds) | |
c08d0e64 | 82 | { |
1ca1b917 | 83 | struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
c08d0e64 MW |
84 | int i; |
85 | ||
1ca1b917 | 86 | if (keysize != CHACHA_KEY_SIZE) |
c08d0e64 MW |
87 | return -EINVAL; |
88 | ||
89 | for (i = 0; i < ARRAY_SIZE(ctx->key); i++) | |
dbd872a1 | 90 | ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32)); |
c08d0e64 | 91 | |
1ca1b917 | 92 | ctx->nrounds = nrounds; |
c08d0e64 MW |
93 | return 0; |
94 | } | |
1ca1b917 EB |
95 | |
96 | int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, | |
97 | unsigned int keysize) | |
98 | { | |
99 | return chacha_setkey(tfm, key, keysize, 20); | |
100 | } | |
31d7247d | 101 | EXPORT_SYMBOL_GPL(crypto_chacha20_setkey); |
c08d0e64 | 102 | |
aa762409 EB |
103 | int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key, |
104 | unsigned int keysize) | |
105 | { | |
106 | return chacha_setkey(tfm, key, keysize, 12); | |
107 | } | |
108 | EXPORT_SYMBOL_GPL(crypto_chacha12_setkey); | |
109 | ||
1ca1b917 | 110 | int crypto_chacha_crypt(struct skcipher_request *req) |
c08d0e64 | 111 | { |
9ae433bc | 112 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
1ca1b917 | 113 | struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
c08d0e64 | 114 | |
1ca1b917 | 115 | return chacha_stream_xor(req, ctx, req->iv); |
de61d7ae | 116 | } |
1ca1b917 | 117 | EXPORT_SYMBOL_GPL(crypto_chacha_crypt); |
c08d0e64 | 118 | |
1ca1b917 | 119 | int crypto_xchacha_crypt(struct skcipher_request *req) |
de61d7ae EB |
120 | { |
121 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); | |
1ca1b917 EB |
122 | struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
123 | struct chacha_ctx subctx; | |
de61d7ae EB |
124 | u32 state[16]; |
125 | u8 real_iv[16]; | |
4de43726 | 126 | |
de61d7ae | 127 | /* Compute the subkey given the original key and first 128 nonce bits */ |
1ca1b917 EB |
128 | crypto_chacha_init(state, ctx, req->iv); |
129 | hchacha_block(state, subctx.key, ctx->nrounds); | |
130 | subctx.nrounds = ctx->nrounds; | |
4de43726 | 131 | |
de61d7ae EB |
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 */ | |
c08d0e64 | 135 | |
de61d7ae | 136 | /* Generate the stream and XOR it with the data */ |
1ca1b917 | 137 | return chacha_stream_xor(req, &subctx, real_iv); |
c08d0e64 | 138 | } |
1ca1b917 | 139 | EXPORT_SYMBOL_GPL(crypto_xchacha_crypt); |
de61d7ae EB |
140 | |
141 | static 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, | |
1ca1b917 | 147 | .base.cra_ctxsize = sizeof(struct chacha_ctx), |
de61d7ae EB |
148 | .base.cra_module = THIS_MODULE, |
149 | ||
1ca1b917 EB |
150 | .min_keysize = CHACHA_KEY_SIZE, |
151 | .max_keysize = CHACHA_KEY_SIZE, | |
152 | .ivsize = CHACHA_IV_SIZE, | |
153 | .chunksize = CHACHA_BLOCK_SIZE, | |
de61d7ae | 154 | .setkey = crypto_chacha20_setkey, |
1ca1b917 EB |
155 | .encrypt = crypto_chacha_crypt, |
156 | .decrypt = crypto_chacha_crypt, | |
de61d7ae EB |
157 | }, { |
158 | .base.cra_name = "xchacha20", | |
159 | .base.cra_driver_name = "xchacha20-generic", | |
160 | .base.cra_priority = 100, | |
161 | .base.cra_blocksize = 1, | |
1ca1b917 | 162 | .base.cra_ctxsize = sizeof(struct chacha_ctx), |
de61d7ae EB |
163 | .base.cra_module = THIS_MODULE, |
164 | ||
1ca1b917 EB |
165 | .min_keysize = CHACHA_KEY_SIZE, |
166 | .max_keysize = CHACHA_KEY_SIZE, | |
167 | .ivsize = XCHACHA_IV_SIZE, | |
168 | .chunksize = CHACHA_BLOCK_SIZE, | |
de61d7ae | 169 | .setkey = crypto_chacha20_setkey, |
1ca1b917 EB |
170 | .encrypt = crypto_xchacha_crypt, |
171 | .decrypt = crypto_xchacha_crypt, | |
aa762409 EB |
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, | |
de61d7ae | 187 | } |
c08d0e64 MW |
188 | }; |
189 | ||
1ca1b917 | 190 | static int __init chacha_generic_mod_init(void) |
c08d0e64 | 191 | { |
de61d7ae | 192 | return crypto_register_skciphers(algs, ARRAY_SIZE(algs)); |
c08d0e64 MW |
193 | } |
194 | ||
1ca1b917 | 195 | static void __exit chacha_generic_mod_fini(void) |
c08d0e64 | 196 | { |
de61d7ae | 197 | crypto_unregister_skciphers(algs, ARRAY_SIZE(algs)); |
c08d0e64 MW |
198 | } |
199 | ||
c4741b23 | 200 | subsys_initcall(chacha_generic_mod_init); |
1ca1b917 | 201 | module_exit(chacha_generic_mod_fini); |
c08d0e64 MW |
202 | |
203 | MODULE_LICENSE("GPL"); | |
204 | MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); | |
1ca1b917 | 205 | MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)"); |
c08d0e64 MW |
206 | MODULE_ALIAS_CRYPTO("chacha20"); |
207 | MODULE_ALIAS_CRYPTO("chacha20-generic"); | |
de61d7ae EB |
208 | MODULE_ALIAS_CRYPTO("xchacha20"); |
209 | MODULE_ALIAS_CRYPTO("xchacha20-generic"); | |
aa762409 EB |
210 | MODULE_ALIAS_CRYPTO("xchacha12"); |
211 | MODULE_ALIAS_CRYPTO("xchacha12-generic"); |