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 15 static 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 34 static int chacha_stream_xor(struct skcipher_request *req, 35 struct chacha_ctx *ctx, 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 59 void crypto_chacha_init(u32 *state, struct chacha_ctx *ctx, 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 } 78 EXPORT_SYMBOL_GPL(crypto_chacha_init); 79 80 static 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 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 } 101 EXPORT_SYMBOL_GPL(crypto_chacha20_setkey); 102 103 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); 109 110 int 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 } 117 EXPORT_SYMBOL_GPL(crypto_chacha_crypt); 118 119 int 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 } 139 EXPORT_SYMBOL_GPL(crypto_xchacha_crypt); 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, 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 }; 189 190 static int __init chacha_generic_mod_init(void) 191 { 192 return crypto_register_skciphers(algs, ARRAY_SIZE(algs)); 193 } 194 195 static void __exit chacha_generic_mod_fini(void) 196 { 197 crypto_unregister_skciphers(algs, ARRAY_SIZE(algs)); 198 } 199 200 subsys_initcall(chacha_generic_mod_init); 201 module_exit(chacha_generic_mod_fini); 202 203 MODULE_LICENSE("GPL"); 204 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); 205 MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)"); 206 MODULE_ALIAS_CRYPTO("chacha20"); 207 MODULE_ALIAS_CRYPTO("chacha20-generic"); 208 MODULE_ALIAS_CRYPTO("xchacha20"); 209 MODULE_ALIAS_CRYPTO("xchacha20-generic"); 210 MODULE_ALIAS_CRYPTO("xchacha12"); 211 MODULE_ALIAS_CRYPTO("xchacha12-generic"); 212