// 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");