mirror of
https://github.com/torvalds/linux.git
synced 2025-11-04 02:30:34 +02:00
20a1acb68d
Rename chacha.c to chacha-block-generic.c to free up the name chacha.c for the high-level API entry points (chacha_crypt() and hchacha_block()), similar to the other algorithms. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20250827151131.27733-5-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org>
114 lines
3.9 KiB
C
114 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* The "hash function" used as the core of the ChaCha stream cipher (RFC7539)
|
|
*
|
|
* Copyright (C) 2015 Martin Willi
|
|
*/
|
|
|
|
#include <crypto/chacha.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/bug.h>
|
|
#include <linux/export.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/string.h>
|
|
#include <linux/unaligned.h>
|
|
|
|
static void chacha_permute(struct chacha_state *state, int nrounds)
|
|
{
|
|
u32 *x = state->x;
|
|
int i;
|
|
|
|
/* whitelist the allowed round counts */
|
|
WARN_ON_ONCE(nrounds != 20 && nrounds != 12);
|
|
|
|
for (i = 0; i < nrounds; i += 2) {
|
|
x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 16);
|
|
x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 16);
|
|
x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 16);
|
|
x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 16);
|
|
|
|
x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 12);
|
|
x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 12);
|
|
x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 12);
|
|
x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 12);
|
|
|
|
x[0] += x[4]; x[12] = rol32(x[12] ^ x[0], 8);
|
|
x[1] += x[5]; x[13] = rol32(x[13] ^ x[1], 8);
|
|
x[2] += x[6]; x[14] = rol32(x[14] ^ x[2], 8);
|
|
x[3] += x[7]; x[15] = rol32(x[15] ^ x[3], 8);
|
|
|
|
x[8] += x[12]; x[4] = rol32(x[4] ^ x[8], 7);
|
|
x[9] += x[13]; x[5] = rol32(x[5] ^ x[9], 7);
|
|
x[10] += x[14]; x[6] = rol32(x[6] ^ x[10], 7);
|
|
x[11] += x[15]; x[7] = rol32(x[7] ^ x[11], 7);
|
|
|
|
x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 16);
|
|
x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 16);
|
|
x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 16);
|
|
x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 16);
|
|
|
|
x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 12);
|
|
x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 12);
|
|
x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 12);
|
|
x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 12);
|
|
|
|
x[0] += x[5]; x[15] = rol32(x[15] ^ x[0], 8);
|
|
x[1] += x[6]; x[12] = rol32(x[12] ^ x[1], 8);
|
|
x[2] += x[7]; x[13] = rol32(x[13] ^ x[2], 8);
|
|
x[3] += x[4]; x[14] = rol32(x[14] ^ x[3], 8);
|
|
|
|
x[10] += x[15]; x[5] = rol32(x[5] ^ x[10], 7);
|
|
x[11] += x[12]; x[6] = rol32(x[6] ^ x[11], 7);
|
|
x[8] += x[13]; x[7] = rol32(x[7] ^ x[8], 7);
|
|
x[9] += x[14]; x[4] = rol32(x[4] ^ x[9], 7);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* chacha_block_generic - generate one keystream block and increment block counter
|
|
* @state: input state matrix
|
|
* @out: output keystream block
|
|
* @nrounds: number of rounds (20 or 12; 20 is recommended)
|
|
*
|
|
* This is the ChaCha core, a function from 64-byte strings to 64-byte strings.
|
|
* The caller has already converted the endianness of the input. This function
|
|
* also handles incrementing the block counter in the input matrix.
|
|
*/
|
|
void chacha_block_generic(struct chacha_state *state,
|
|
u8 out[CHACHA_BLOCK_SIZE], int nrounds)
|
|
{
|
|
struct chacha_state permuted_state = *state;
|
|
int i;
|
|
|
|
chacha_permute(&permuted_state, nrounds);
|
|
|
|
for (i = 0; i < ARRAY_SIZE(state->x); i++)
|
|
put_unaligned_le32(permuted_state.x[i] + state->x[i],
|
|
&out[i * sizeof(u32)]);
|
|
|
|
state->x[12]++;
|
|
}
|
|
EXPORT_SYMBOL(chacha_block_generic);
|
|
|
|
/**
|
|
* hchacha_block_generic - abbreviated ChaCha core, for XChaCha
|
|
* @state: input state matrix
|
|
* @out: the output words
|
|
* @nrounds: number of rounds (20 or 12; 20 is recommended)
|
|
*
|
|
* HChaCha is the ChaCha equivalent of HSalsa and is an intermediate step
|
|
* towards XChaCha (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf). HChaCha
|
|
* skips the final addition of the initial state, and outputs only certain words
|
|
* of the state. It should not be used for streaming directly.
|
|
*/
|
|
void hchacha_block_generic(const struct chacha_state *state,
|
|
u32 out[HCHACHA_OUT_WORDS], int nrounds)
|
|
{
|
|
struct chacha_state permuted_state = *state;
|
|
|
|
chacha_permute(&permuted_state, nrounds);
|
|
|
|
memcpy(&out[0], &permuted_state.x[0], 16);
|
|
memcpy(&out[4], &permuted_state.x[12], 16);
|
|
}
|
|
EXPORT_SYMBOL(hchacha_block_generic);
|