diff options
Diffstat (limited to 'crypto/chacha20_generic.c')
| -rw-r--r-- | crypto/chacha20_generic.c | 120 |
1 files changed, 84 insertions, 36 deletions
diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c index 3529521d72a4..4305b1b62b16 100644 --- a/crypto/chacha20_generic.c +++ b/crypto/chacha20_generic.c @@ -1,7 +1,8 @@ /* - * ChaCha20 256-bit cipher algorithm, RFC7539 + * ChaCha20 (RFC7539) and XChaCha20 stream cipher algorithms * * Copyright (C) 2015 Martin Willi + * Copyright (C) 2018 Google LLC * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -36,6 +37,31 @@ static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src, } } +static int chacha20_stream_xor(struct skcipher_request *req, + struct chacha20_ctx *ctx, u8 *iv) +{ + struct skcipher_walk walk; + u32 state[16]; + int err; + + err = skcipher_walk_virt(&walk, req, false); + + crypto_chacha20_init(state, ctx, iv); + + while (walk.nbytes > 0) { + unsigned int nbytes = walk.nbytes; + + if (nbytes < walk.total) + nbytes = round_down(nbytes, walk.stride); + + chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, + nbytes); + err = skcipher_walk_done(&walk, walk.nbytes - nbytes); + } + + return err; +} + void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv) { state[0] = 0x61707865; /* "expa" */ @@ -77,54 +103,74 @@ int crypto_chacha20_crypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm); - struct skcipher_walk walk; - u32 state[16]; - int err; - - err = skcipher_walk_virt(&walk, req, false); - crypto_chacha20_init(state, ctx, walk.iv); + return chacha20_stream_xor(req, ctx, req->iv); +} +EXPORT_SYMBOL_GPL(crypto_chacha20_crypt); - while (walk.nbytes > 0) { - unsigned int nbytes = walk.nbytes; +int crypto_xchacha20_crypt(struct skcipher_request *req) +{ + struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); + struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm); + struct chacha20_ctx subctx; + u32 state[16]; + u8 real_iv[16]; - if (nbytes < walk.total) - nbytes = round_down(nbytes, walk.stride); + /* Compute the subkey given the original key and first 128 nonce bits */ + crypto_chacha20_init(state, ctx, req->iv); + hchacha20_block(state, subctx.key); - chacha20_docrypt(state, walk.dst.virt.addr, walk.src.virt.addr, - nbytes); - err = skcipher_walk_done(&walk, walk.nbytes - nbytes); - } + /* 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 */ - return err; + /* Generate the stream and XOR it with the data */ + return chacha20_stream_xor(req, &subctx, real_iv); } -EXPORT_SYMBOL_GPL(crypto_chacha20_crypt); - -static struct skcipher_alg alg = { - .base.cra_name = "chacha20", - .base.cra_driver_name = "chacha20-generic", - .base.cra_priority = 100, - .base.cra_blocksize = 1, - .base.cra_ctxsize = sizeof(struct chacha20_ctx), - .base.cra_module = THIS_MODULE, - - .min_keysize = CHACHA20_KEY_SIZE, - .max_keysize = CHACHA20_KEY_SIZE, - .ivsize = CHACHA20_IV_SIZE, - .chunksize = CHACHA20_BLOCK_SIZE, - .setkey = crypto_chacha20_setkey, - .encrypt = crypto_chacha20_crypt, - .decrypt = crypto_chacha20_crypt, +EXPORT_SYMBOL_GPL(crypto_xchacha20_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 chacha20_ctx), + .base.cra_module = THIS_MODULE, + + .min_keysize = CHACHA20_KEY_SIZE, + .max_keysize = CHACHA20_KEY_SIZE, + .ivsize = CHACHA20_IV_SIZE, + .chunksize = CHACHA20_BLOCK_SIZE, + .setkey = crypto_chacha20_setkey, + .encrypt = crypto_chacha20_crypt, + .decrypt = crypto_chacha20_crypt, + }, { + .base.cra_name = "xchacha20", + .base.cra_driver_name = "xchacha20-generic", + .base.cra_priority = 100, + .base.cra_blocksize = 1, + .base.cra_ctxsize = sizeof(struct chacha20_ctx), + .base.cra_module = THIS_MODULE, + + .min_keysize = CHACHA20_KEY_SIZE, + .max_keysize = CHACHA20_KEY_SIZE, + .ivsize = XCHACHA20_IV_SIZE, + .chunksize = CHACHA20_BLOCK_SIZE, + .setkey = crypto_chacha20_setkey, + .encrypt = crypto_xchacha20_crypt, + .decrypt = crypto_xchacha20_crypt, + } }; static int __init chacha20_generic_mod_init(void) { - return crypto_register_skcipher(&alg); + return crypto_register_skciphers(algs, ARRAY_SIZE(algs)); } static void __exit chacha20_generic_mod_fini(void) { - crypto_unregister_skcipher(&alg); + crypto_unregister_skciphers(algs, ARRAY_SIZE(algs)); } module_init(chacha20_generic_mod_init); @@ -132,6 +178,8 @@ module_exit(chacha20_generic_mod_fini); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Martin Willi <martin@strongswan.org>"); -MODULE_DESCRIPTION("chacha20 cipher algorithm"); +MODULE_DESCRIPTION("ChaCha20 and XChaCha20 stream ciphers (generic)"); MODULE_ALIAS_CRYPTO("chacha20"); MODULE_ALIAS_CRYPTO("chacha20-generic"); +MODULE_ALIAS_CRYPTO("xchacha20"); +MODULE_ALIAS_CRYPTO("xchacha20-generic"); |