mirror of
https://github.com/koverstreet/bcachefs-tools.git
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112 lines
2.4 KiB
C
112 lines
2.4 KiB
C
/*
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* ChaCha20 256-bit cipher algorithm, RFC7539
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*
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* Copyright (C) 2015 Martin Willi
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/byteorder.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/scatterlist.h>
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#include <asm/unaligned.h>
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#include <linux/crypto.h>
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#include <crypto/algapi.h>
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#include <crypto/chacha.h>
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#include <crypto/skcipher.h>
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#include <sodium/crypto_stream_chacha20.h>
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static struct skcipher_alg alg;
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struct chacha20_tfm {
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struct crypto_skcipher tfm;
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u32 key[8];
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};
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static int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
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unsigned int keysize)
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{
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struct chacha20_tfm *ctx =
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container_of(tfm, struct chacha20_tfm, tfm);
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int i;
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if (keysize != CHACHA_KEY_SIZE)
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return -EINVAL;
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for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
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ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));
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return 0;
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}
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static int crypto_chacha20_crypt(struct skcipher_request *req)
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{
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struct chacha20_tfm *ctx =
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container_of(req->tfm, struct chacha20_tfm, tfm.base);
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struct scatterlist *sg = req->src;
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unsigned nbytes = req->cryptlen;
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u32 iv[4];
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int ret;
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BUG_ON(req->src != req->dst);
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memcpy(iv, req->iv, sizeof(iv));
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while (1) {
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ret = crypto_stream_chacha20_xor_ic(sg_virt(sg),
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sg_virt(sg),
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sg->length,
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(void *) &iv[2],
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iv[0] | ((u64) iv[1] << 32),
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(void *) ctx->key);
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BUG_ON(ret);
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nbytes -= sg->length;
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if (sg_is_last(sg))
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break;
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BUG_ON(sg->length % CHACHA_BLOCK_SIZE);
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iv[0] += sg->length / CHACHA_BLOCK_SIZE;
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sg = sg_next(sg);
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};
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BUG_ON(nbytes);
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return 0;
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}
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static void *crypto_chacha20_alloc_tfm(void)
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{
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struct chacha20_tfm *tfm = kzalloc(sizeof(*tfm), GFP_KERNEL);
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if (!tfm)
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return NULL;
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tfm->tfm.base.alg = &alg.base;
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tfm->tfm.setkey = crypto_chacha20_setkey;
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tfm->tfm.encrypt = crypto_chacha20_crypt;
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tfm->tfm.decrypt = crypto_chacha20_crypt;
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tfm->tfm.ivsize = CHACHA_IV_SIZE;
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tfm->tfm.keysize = CHACHA_KEY_SIZE;
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return tfm;
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}
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static struct skcipher_alg alg = {
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.base.cra_name = "chacha20",
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.base.alloc_tfm = crypto_chacha20_alloc_tfm,
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};
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__attribute__((constructor(110)))
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static int chacha20_generic_mod_init(void)
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{
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return crypto_register_skcipher(&alg);
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}
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