diff options
Diffstat (limited to 'lib/crypto/chacha.c')
| -rw-r--r-- | lib/crypto/chacha.c | 146 |
1 files changed, 51 insertions, 95 deletions
diff --git a/lib/crypto/chacha.c b/lib/crypto/chacha.c index b748fd3d256e..e0c7cb4af318 100644 --- a/lib/crypto/chacha.c +++ b/lib/crypto/chacha.c @@ -1,114 +1,70 @@ // SPDX-License-Identifier: GPL-2.0-or-later /* - * The "hash function" used as the core of the ChaCha stream cipher (RFC7539) + * The ChaCha stream cipher (RFC7539) * * Copyright (C) 2015 Martin Willi */ -#include <linux/bug.h> -#include <linux/kernel.h> -#include <linux/export.h> -#include <linux/bitops.h> -#include <linux/string.h> -#include <asm/unaligned.h> +#include <crypto/algapi.h> // for crypto_xor_cpy #include <crypto/chacha.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/module.h> -static void chacha_permute(u32 *x, int nrounds) +static void __maybe_unused +chacha_crypt_generic(struct chacha_state *state, u8 *dst, const u8 *src, + unsigned int bytes, int nrounds) { - 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); + /* aligned to potentially speed up crypto_xor() */ + u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long)); + + while (bytes >= CHACHA_BLOCK_SIZE) { + chacha_block_generic(state, stream, nrounds); + crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE); + bytes -= CHACHA_BLOCK_SIZE; + dst += CHACHA_BLOCK_SIZE; + src += CHACHA_BLOCK_SIZE; + } + if (bytes) { + chacha_block_generic(state, stream, nrounds); + crypto_xor_cpy(dst, src, stream, bytes); } } -/** - * chacha_block_generic - generate one keystream block and increment block counter - * @state: input state matrix (16 32-bit words) - * @stream: output keystream block (64 bytes) - * @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(u32 *state, u8 *stream, int nrounds) -{ - u32 x[16]; - int i; - - memcpy(x, state, 64); - - chacha_permute(x, nrounds); +#ifdef CONFIG_CRYPTO_LIB_CHACHA_ARCH +#include "chacha.h" /* $(SRCARCH)/chacha.h */ +#else +#define chacha_crypt_arch chacha_crypt_generic +#define hchacha_block_arch hchacha_block_generic +#endif - for (i = 0; i < ARRAY_SIZE(x); i++) - put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]); - - state[12]++; +void chacha_crypt(struct chacha_state *state, u8 *dst, const u8 *src, + unsigned int bytes, int nrounds) +{ + chacha_crypt_arch(state, dst, src, bytes, nrounds); } -EXPORT_SYMBOL(chacha_block_generic); +EXPORT_SYMBOL_GPL(chacha_crypt); -/** - * hchacha_block_generic - abbreviated ChaCha core, for XChaCha - * @state: input state matrix (16 32-bit words) - * @stream: output (8 32-bit 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 u32 *state, u32 *stream, int nrounds) +void hchacha_block(const struct chacha_state *state, + u32 out[HCHACHA_OUT_WORDS], int nrounds) { - u32 x[16]; - - memcpy(x, state, 64); + hchacha_block_arch(state, out, nrounds); +} +EXPORT_SYMBOL_GPL(hchacha_block); - chacha_permute(x, nrounds); +#ifdef chacha_mod_init_arch +static int __init chacha_mod_init(void) +{ + chacha_mod_init_arch(); + return 0; +} +subsys_initcall(chacha_mod_init); - memcpy(&stream[0], &x[0], 16); - memcpy(&stream[4], &x[12], 16); +static void __exit chacha_mod_exit(void) +{ } -EXPORT_SYMBOL(hchacha_block_generic); +module_exit(chacha_mod_exit); +#endif + +MODULE_DESCRIPTION("ChaCha stream cipher (RFC7539)"); +MODULE_LICENSE("GPL"); |