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139 lines
3.9 KiB
139 lines
3.9 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* ChaCha and XChaCha stream ciphers, including ChaCha20 (RFC7539) |
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* |
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* Copyright (C) 2015 Martin Willi |
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* Copyright (C) 2018 Google LLC |
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*/ |
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#include <asm/unaligned.h> |
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#include <crypto/algapi.h> |
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#include <crypto/internal/chacha.h> |
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#include <crypto/internal/skcipher.h> |
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#include <linux/module.h> |
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static int chacha_stream_xor(struct skcipher_request *req, |
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const struct chacha_ctx *ctx, const u8 *iv) |
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{ |
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struct skcipher_walk walk; |
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u32 state[16]; |
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int err; |
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err = skcipher_walk_virt(&walk, req, false); |
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chacha_init_generic(state, ctx->key, iv); |
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while (walk.nbytes > 0) { |
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unsigned int nbytes = walk.nbytes; |
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if (nbytes < walk.total) |
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nbytes = round_down(nbytes, CHACHA_BLOCK_SIZE); |
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chacha_crypt_generic(state, walk.dst.virt.addr, |
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walk.src.virt.addr, nbytes, ctx->nrounds); |
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err = skcipher_walk_done(&walk, walk.nbytes - nbytes); |
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} |
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return err; |
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} |
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static int crypto_chacha_crypt(struct skcipher_request *req) |
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{ |
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
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struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
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return chacha_stream_xor(req, ctx, req->iv); |
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} |
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static int crypto_xchacha_crypt(struct skcipher_request *req) |
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{ |
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
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struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm); |
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struct chacha_ctx subctx; |
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u32 state[16]; |
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u8 real_iv[16]; |
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/* Compute the subkey given the original key and first 128 nonce bits */ |
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chacha_init_generic(state, ctx->key, req->iv); |
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hchacha_block_generic(state, subctx.key, ctx->nrounds); |
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subctx.nrounds = ctx->nrounds; |
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/* Build the real IV */ |
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memcpy(&real_iv[0], req->iv + 24, 8); /* stream position */ |
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memcpy(&real_iv[8], req->iv + 16, 8); /* remaining 64 nonce bits */ |
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/* Generate the stream and XOR it with the data */ |
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return chacha_stream_xor(req, &subctx, real_iv); |
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} |
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static struct skcipher_alg algs[] = { |
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{ |
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.base.cra_name = "chacha20", |
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.base.cra_driver_name = "chacha20-generic", |
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.base.cra_priority = 100, |
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.base.cra_blocksize = 1, |
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.base.cra_ctxsize = sizeof(struct chacha_ctx), |
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.base.cra_module = THIS_MODULE, |
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.min_keysize = CHACHA_KEY_SIZE, |
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.max_keysize = CHACHA_KEY_SIZE, |
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.ivsize = CHACHA_IV_SIZE, |
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.chunksize = CHACHA_BLOCK_SIZE, |
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.setkey = chacha20_setkey, |
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.encrypt = crypto_chacha_crypt, |
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.decrypt = crypto_chacha_crypt, |
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}, { |
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.base.cra_name = "xchacha20", |
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.base.cra_driver_name = "xchacha20-generic", |
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.base.cra_priority = 100, |
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.base.cra_blocksize = 1, |
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.base.cra_ctxsize = sizeof(struct chacha_ctx), |
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.base.cra_module = THIS_MODULE, |
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.min_keysize = CHACHA_KEY_SIZE, |
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.max_keysize = CHACHA_KEY_SIZE, |
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.ivsize = XCHACHA_IV_SIZE, |
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.chunksize = CHACHA_BLOCK_SIZE, |
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.setkey = chacha20_setkey, |
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.encrypt = crypto_xchacha_crypt, |
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.decrypt = crypto_xchacha_crypt, |
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}, { |
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.base.cra_name = "xchacha12", |
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.base.cra_driver_name = "xchacha12-generic", |
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.base.cra_priority = 100, |
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.base.cra_blocksize = 1, |
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.base.cra_ctxsize = sizeof(struct chacha_ctx), |
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.base.cra_module = THIS_MODULE, |
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.min_keysize = CHACHA_KEY_SIZE, |
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.max_keysize = CHACHA_KEY_SIZE, |
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.ivsize = XCHACHA_IV_SIZE, |
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.chunksize = CHACHA_BLOCK_SIZE, |
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.setkey = chacha12_setkey, |
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.encrypt = crypto_xchacha_crypt, |
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.decrypt = crypto_xchacha_crypt, |
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} |
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}; |
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static int __init chacha_generic_mod_init(void) |
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{ |
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return crypto_register_skciphers(algs, ARRAY_SIZE(algs)); |
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} |
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static void __exit chacha_generic_mod_fini(void) |
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{ |
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crypto_unregister_skciphers(algs, ARRAY_SIZE(algs)); |
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} |
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subsys_initcall(chacha_generic_mod_init); |
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module_exit(chacha_generic_mod_fini); |
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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("Martin Willi <[email protected]>"); |
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MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (generic)"); |
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MODULE_ALIAS_CRYPTO("chacha20"); |
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MODULE_ALIAS_CRYPTO("chacha20-generic"); |
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MODULE_ALIAS_CRYPTO("xchacha20"); |
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MODULE_ALIAS_CRYPTO("xchacha20-generic"); |
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MODULE_ALIAS_CRYPTO("xchacha12"); |
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MODULE_ALIAS_CRYPTO("xchacha12-generic");
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