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