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// SPDX-License-Identifier: GPL-2.0 OR MIT
/*
* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*
* This is an implementation of the ChaCha20Poly1305 AEAD construction.
*
* Information: https://tools.ietf.org/html/rfc8439
*/
#include <crypto/algapi.h>
#include <crypto/chacha20poly1305.h>
#include <crypto/chacha.h>
#include <crypto/poly1305.h>
#include <asm/unaligned.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#define CHACHA_KEY_WORDS (CHACHA_KEY_SIZE / sizeof(u32))
bool __init chacha20poly1305_selftest(void);
static void chacha_load_key(u32 *k, const u8 *in)
{
k[0] = get_unaligned_le32(in);
k[1] = get_unaligned_le32(in + 4);
k[2] = get_unaligned_le32(in + 8);
k[3] = get_unaligned_le32(in + 12);
k[4] = get_unaligned_le32(in + 16);
k[5] = get_unaligned_le32(in + 20);
k[6] = get_unaligned_le32(in + 24);
k[7] = get_unaligned_le32(in + 28);
}
static void xchacha_init(u32 *chacha_state, const u8 *key, const u8 *nonce)
{
u32 k[CHACHA_KEY_WORDS];
u8 iv[CHACHA_IV_SIZE];
memset(iv, 0, 8);
memcpy(iv + 8, nonce + 16, 8);
chacha_load_key(k, key);
/* Compute the subkey given the original key and first 128 nonce bits */
chacha_init(chacha_state, k, nonce);
hchacha_block(chacha_state, k, 20);
chacha_init(chacha_state, k, iv);
memzero_explicit(k, sizeof(k));
memzero_explicit(iv, sizeof(iv));
}
static void
__chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
const u8 *ad, const size_t ad_len, u32 *chacha_state)
{
const u8 *pad0 = page_address(ZERO_PAGE(0));
struct poly1305_desc_ctx poly1305_state;
union {
u8 block0[POLY1305_KEY_SIZE];
__le64 lens[2];
} b;
chacha_crypt(chacha_state, b.block0, pad0, sizeof(b.block0), 20);
poly1305_init(&poly1305_state, b.block0);
poly1305_update(&poly1305_state, ad, ad_len);
if (ad_len & 0xf)
poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));
chacha_crypt(chacha_state, dst, src, src_len, 20);
poly1305_update(&poly1305_state, dst, src_len);
if (src_len & 0xf)
poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf));
b.lens[0] = cpu_to_le64(ad_len);
b.lens[1] = cpu_to_le64(src_len);
poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));
poly1305_final(&poly1305_state, dst + src_len);
memzero_explicit(chacha_state, CHACHA_STATE_WORDS * sizeof(u32));
memzero_explicit(&b, sizeof(b));
}
void chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
const u8 *ad, const size_t ad_len,
const u64 nonce,
const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
u32 chacha_state[CHACHA_STATE_WORDS];
u32 k[CHACHA_KEY_WORDS];
__le64 iv[2];
chacha_load_key(k, key);
iv[0] = 0;
iv[1] = cpu_to_le64(nonce);
chacha_init(chacha_state, k, (u8 *)iv);
__chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, chacha_state);
memzero_explicit(iv, sizeof(iv));
memzero_explicit(k, sizeof(k));
}
EXPORT_SYMBOL(chacha20poly1305_encrypt);
void xchacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
const u8 *ad, const size_t ad_len,
const u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
u32 chacha_state[CHACHA_STATE_WORDS];
xchacha_init(chacha_state, key, nonce);
__chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, chacha_state);
}
EXPORT_SYMBOL(xchacha20poly1305_encrypt);
static bool
__chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
const u8 *ad, const size_t ad_len, u32 *chacha_state)
{
const u8 *pad0 = page_address(ZERO_PAGE(0));
struct poly1305_desc_ctx poly1305_state;
size_t dst_len;
int ret;
union {
u8 block0[POLY1305_KEY_SIZE];
u8 mac[POLY1305_DIGEST_SIZE];
__le64 lens[2];
} b;
if (unlikely(src_len < POLY1305_DIGEST_SIZE))
return false;
chacha_crypt(chacha_state, b.block0, pad0, sizeof(b.block0), 20);
poly1305_init(&poly1305_state, b.block0);
poly1305_update(&poly1305_state, ad, ad_len);
if (ad_len & 0xf)
poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));
dst_len = src_len - POLY1305_DIGEST_SIZE;
poly1305_update(&poly1305_state, src, dst_len);
if (dst_len & 0xf)
poly1305_update(&poly1305_state, pad0, 0x10 - (dst_len & 0xf));
b.lens[0] = cpu_to_le64(ad_len);
b.lens[1] = cpu_to_le64(dst_len);
poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));
poly1305_final(&poly1305_state, b.mac);
ret = crypto_memneq(b.mac, src + dst_len, POLY1305_DIGEST_SIZE);
if (likely(!ret))
chacha_crypt(chacha_state, dst, src, dst_len, 20);
memzero_explicit(&b, sizeof(b));
return !ret;
}
bool chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
const u8 *ad, const size_t ad_len,
const u64 nonce,
const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
u32 chacha_state[CHACHA_STATE_WORDS];
u32 k[CHACHA_KEY_WORDS];
__le64 iv[2];
bool ret;
chacha_load_key(k, key);
iv[0] = 0;
iv[1] = cpu_to_le64(nonce);
chacha_init(chacha_state, k, (u8 *)iv);
ret = __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len,
chacha_state);
memzero_explicit(chacha_state, sizeof(chacha_state));
memzero_explicit(iv, sizeof(iv));
memzero_explicit(k, sizeof(k));
return ret;
}
EXPORT_SYMBOL(chacha20poly1305_decrypt);
bool xchacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
const u8 *ad, const size_t ad_len,
const u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
u32 chacha_state[CHACHA_STATE_WORDS];
xchacha_init(chacha_state, key, nonce);
return __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len,
chacha_state);
}
EXPORT_SYMBOL(xchacha20poly1305_decrypt);
static int __init mod_init(void)
{
if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS) &&
WARN_ON(!chacha20poly1305_selftest()))
return -ENODEV;
return 0;
}
module_init(mod_init);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChaCha20Poly1305 AEAD construction");
MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");
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