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Diffstat (limited to '')
| -rw-r--r-- | crypto/chacha_generic.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/crypto/chacha_generic.c b/crypto/chacha_generic.c new file mode 100644 index 000000000..8beea79ab --- /dev/null +++ b/crypto/chacha_generic.c @@ -0,0 +1,139 @@ +// 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/internal/chacha.h> +#include <crypto/internal/skcipher.h> +#include <linux/module.h> + +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); + + chacha_init_generic(state, ctx->key, iv); + + while (walk.nbytes > 0) { + unsigned int nbytes = walk.nbytes; + + if (nbytes < walk.total) + nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE); + + chacha_crypt_generic(state, walk.dst.virt.addr, + walk.src.virt.addr, nbytes, ctx->nrounds); + err = skcipher_walk_done(&walk, walk.nbytes - nbytes); + } + + return err; +} + +static 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); +} + +static 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 */ + chacha_init_generic(state, ctx->key, req->iv); + hchacha_block_generic(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); +} + +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 = 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 = 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 = 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"); |