Commit | Line | Data |
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c08d0e64 | 1 | /* |
aa762409 | 2 | * ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539) |
c08d0e64 MW |
3 | * |
4 | * Copyright (C) 2015 Martin Willi | |
de61d7ae | 5 | * Copyright (C) 2018 Google LLC |
c08d0e64 MW |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | */ | |
12 | ||
dbd872a1 | 13 | #include <asm/unaligned.h> |
c08d0e64 | 14 | #include <crypto/algapi.h> |
1ca1b917 | 15 | #include <crypto/chacha.h> |
9ae433bc AB |
16 | #include <crypto/internal/skcipher.h> |
17 | #include <linux/module.h> | |
c08d0e64 | 18 | |
1ca1b917 EB |
19 | static void chacha_docrypt(u32 *state, u8 *dst, const u8 *src, |
20 | unsigned int bytes, int nrounds) | |
c08d0e64 | 21 | { |
a5e9f557 | 22 | /* aligned to potentially speed up crypto_xor() */ |
1ca1b917 | 23 | u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long)); |
c08d0e64 MW |
24 | |
25 | if (dst != src) | |
26 | memcpy(dst, src, bytes); | |
27 | ||
1ca1b917 EB |
28 | while (bytes >= CHACHA_BLOCK_SIZE) { |
29 | chacha_block(state, stream, nrounds); | |
30 | crypto_xor(dst, stream, CHACHA_BLOCK_SIZE); | |
31 | bytes -= CHACHA_BLOCK_SIZE; | |
32 | dst += CHACHA_BLOCK_SIZE; | |
c08d0e64 MW |
33 | } |
34 | if (bytes) { | |
1ca1b917 | 35 | chacha_block(state, stream, nrounds); |
a5e9f557 | 36 | crypto_xor(dst, stream, bytes); |
c08d0e64 MW |
37 | } |
38 | } | |
39 | ||
1ca1b917 EB |
40 | static int chacha_stream_xor(struct skcipher_request *req, |
41 | struct chacha_ctx *ctx, u8 *iv) | |
de61d7ae EB |
42 | { |
43 | struct skcipher_walk walk; | |
44 | u32 state[16]; | |
45 | int err; | |
46 | ||
47 | err = skcipher_walk_virt(&walk, req, false); | |
48 | ||
1ca1b917 | 49 | crypto_chacha_init(state, ctx, iv); |
de61d7ae EB |
50 | |
51 | while (walk.nbytes > 0) { | |
52 | unsigned int nbytes = walk.nbytes; | |
53 | ||
54 | if (nbytes < walk.total) | |
55 | nbytes = round_down(nbytes, walk.stride); | |
56 | ||
1ca1b917 EB |
57 | chacha_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, |
58 | nbytes, ctx->nrounds); | |
de61d7ae EB |
59 | err = skcipher_walk_done(&walk, walk.nbytes - nbytes); |
60 | } | |
61 | ||
62 | return err; | |
63 | } | |
64 | ||
1ca1b917 | 65 | void crypto_chacha_init(u32 *state, struct chacha_ctx *ctx, u8 *iv) |
c08d0e64 | 66 | { |
ecf3220d EB |
67 | state[0] = 0x61707865; /* "expa" */ |
68 | state[1] = 0x3320646e; /* "nd 3" */ | |
69 | state[2] = 0x79622d32; /* "2-by" */ | |
70 | state[3] = 0x6b206574; /* "te k" */ | |
c08d0e64 MW |
71 | state[4] = ctx->key[0]; |
72 | state[5] = ctx->key[1]; | |
73 | state[6] = ctx->key[2]; | |
74 | state[7] = ctx->key[3]; | |
75 | state[8] = ctx->key[4]; | |
76 | state[9] = ctx->key[5]; | |
77 | state[10] = ctx->key[6]; | |
78 | state[11] = ctx->key[7]; | |
dbd872a1 EB |
79 | state[12] = get_unaligned_le32(iv + 0); |
80 | state[13] = get_unaligned_le32(iv + 4); | |
81 | state[14] = get_unaligned_le32(iv + 8); | |
82 | state[15] = get_unaligned_le32(iv + 12); | |
c08d0e64 | 83 | } |
1ca1b917 | 84 | EXPORT_SYMBOL_GPL(crypto_chacha_init); |
c08d0e64 | 85 | |
1ca1b917 EB |
86 | static int chacha_setkey(struct crypto_skcipher *tfm, const u8 *key, |
87 | unsigned int keysize, int nrounds) | |
c08d0e64 | 88 | { |
1ca1b917 | 89 | struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
c08d0e64 MW |
90 | int i; |
91 | ||
1ca1b917 | 92 | if (keysize != CHACHA_KEY_SIZE) |
c08d0e64 MW |
93 | return -EINVAL; |
94 | ||
95 | for (i = 0; i < ARRAY_SIZE(ctx->key); i++) | |
dbd872a1 | 96 | ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32)); |
c08d0e64 | 97 | |
1ca1b917 | 98 | ctx->nrounds = nrounds; |
c08d0e64 MW |
99 | return 0; |
100 | } | |
1ca1b917 EB |
101 | |
102 | int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, | |
103 | unsigned int keysize) | |
104 | { | |
105 | return chacha_setkey(tfm, key, keysize, 20); | |
106 | } | |
31d7247d | 107 | EXPORT_SYMBOL_GPL(crypto_chacha20_setkey); |
c08d0e64 | 108 | |
aa762409 EB |
109 | int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key, |
110 | unsigned int keysize) | |
111 | { | |
112 | return chacha_setkey(tfm, key, keysize, 12); | |
113 | } | |
114 | EXPORT_SYMBOL_GPL(crypto_chacha12_setkey); | |
115 | ||
1ca1b917 | 116 | int crypto_chacha_crypt(struct skcipher_request *req) |
c08d0e64 | 117 | { |
9ae433bc | 118 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
1ca1b917 | 119 | struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
c08d0e64 | 120 | |
1ca1b917 | 121 | return chacha_stream_xor(req, ctx, req->iv); |
de61d7ae | 122 | } |
1ca1b917 | 123 | EXPORT_SYMBOL_GPL(crypto_chacha_crypt); |
c08d0e64 | 124 | |
1ca1b917 | 125 | int crypto_xchacha_crypt(struct skcipher_request *req) |
de61d7ae EB |
126 | { |
127 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); | |
1ca1b917 EB |
128 | struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
129 | struct chacha_ctx subctx; | |
de61d7ae EB |
130 | u32 state[16]; |
131 | u8 real_iv[16]; | |
4de43726 | 132 | |
de61d7ae | 133 | /* Compute the subkey given the original key and first 128 nonce bits */ |
1ca1b917 EB |
134 | crypto_chacha_init(state, ctx, req->iv); |
135 | hchacha_block(state, subctx.key, ctx->nrounds); | |
136 | subctx.nrounds = ctx->nrounds; | |
4de43726 | 137 | |
de61d7ae EB |
138 | /* Build the real IV */ |
139 | memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */ | |
140 | memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */ | |
c08d0e64 | 141 | |
de61d7ae | 142 | /* Generate the stream and XOR it with the data */ |
1ca1b917 | 143 | return chacha_stream_xor(req, &subctx, real_iv); |
c08d0e64 | 144 | } |
1ca1b917 | 145 | EXPORT_SYMBOL_GPL(crypto_xchacha_crypt); |
de61d7ae EB |
146 | |
147 | static struct skcipher_alg algs[] = { | |
148 | { | |
149 | .base.cra_name = "chacha20", | |
150 | .base.cra_driver_name = "chacha20-generic", | |
151 | .base.cra_priority = 100, | |
152 | .base.cra_blocksize = 1, | |
1ca1b917 | 153 | .base.cra_ctxsize = sizeof(struct chacha_ctx), |
de61d7ae EB |
154 | .base.cra_module = THIS_MODULE, |
155 | ||
1ca1b917 EB |
156 | .min_keysize = CHACHA_KEY_SIZE, |
157 | .max_keysize = CHACHA_KEY_SIZE, | |
158 | .ivsize = CHACHA_IV_SIZE, | |
159 | .chunksize = CHACHA_BLOCK_SIZE, | |
de61d7ae | 160 | .setkey = crypto_chacha20_setkey, |
1ca1b917 EB |
161 | .encrypt = crypto_chacha_crypt, |
162 | .decrypt = crypto_chacha_crypt, | |
de61d7ae EB |
163 | }, { |
164 | .base.cra_name = "xchacha20", | |
165 | .base.cra_driver_name = "xchacha20-generic", | |
166 | .base.cra_priority = 100, | |
167 | .base.cra_blocksize = 1, | |
1ca1b917 | 168 | .base.cra_ctxsize = sizeof(struct chacha_ctx), |
de61d7ae EB |
169 | .base.cra_module = THIS_MODULE, |
170 | ||
1ca1b917 EB |
171 | .min_keysize = CHACHA_KEY_SIZE, |
172 | .max_keysize = CHACHA_KEY_SIZE, | |
173 | .ivsize = XCHACHA_IV_SIZE, | |
174 | .chunksize = CHACHA_BLOCK_SIZE, | |
de61d7ae | 175 | .setkey = crypto_chacha20_setkey, |
1ca1b917 EB |
176 | .encrypt = crypto_xchacha_crypt, |
177 | .decrypt = crypto_xchacha_crypt, | |
aa762409 EB |
178 | }, { |
179 | .base.cra_name = "xchacha12", | |
180 | .base.cra_driver_name = "xchacha12-generic", | |
181 | .base.cra_priority = 100, | |
182 | .base.cra_blocksize = 1, | |
183 | .base.cra_ctxsize = sizeof(struct chacha_ctx), | |
184 | .base.cra_module = THIS_MODULE, | |
185 | ||
186 | .min_keysize = CHACHA_KEY_SIZE, | |
187 | .max_keysize = CHACHA_KEY_SIZE, | |
188 | .ivsize = XCHACHA_IV_SIZE, | |
189 | .chunksize = CHACHA_BLOCK_SIZE, | |
190 | .setkey = crypto_chacha12_setkey, | |
191 | .encrypt = crypto_xchacha_crypt, | |
192 | .decrypt = crypto_xchacha_crypt, | |
de61d7ae | 193 | } |
c08d0e64 MW |
194 | }; |
195 | ||
1ca1b917 | 196 | static int __init chacha_generic_mod_init(void) |
c08d0e64 | 197 | { |
de61d7ae | 198 | return crypto_register_skciphers(algs, ARRAY_SIZE(algs)); |
c08d0e64 MW |
199 | } |
200 | ||
1ca1b917 | 201 | static void __exit chacha_generic_mod_fini(void) |
c08d0e64 | 202 | { |
de61d7ae | 203 | crypto_unregister_skciphers(algs, ARRAY_SIZE(algs)); |
c08d0e64 MW |
204 | } |
205 | ||
1ca1b917 EB |
206 | module_init(chacha_generic_mod_init); |
207 | module_exit(chacha_generic_mod_fini); | |
c08d0e64 MW |
208 | |
209 | MODULE_LICENSE("GPL"); | |
210 | MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); | |
1ca1b917 | 211 | MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)"); |
c08d0e64 MW |
212 | MODULE_ALIAS_CRYPTO("chacha20"); |
213 | MODULE_ALIAS_CRYPTO("chacha20-generic"); | |
de61d7ae EB |
214 | MODULE_ALIAS_CRYPTO("xchacha20"); |
215 | MODULE_ALIAS_CRYPTO("xchacha20-generic"); | |
aa762409 EB |
216 | MODULE_ALIAS_CRYPTO("xchacha12"); |
217 | MODULE_ALIAS_CRYPTO("xchacha12-generic"); |