diff options
Diffstat (limited to 'src/crypto/zinc/chacha20/chacha20.c')
| -rw-r--r-- | src/crypto/zinc/chacha20/chacha20.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/src/crypto/zinc/chacha20/chacha20.c b/src/crypto/zinc/chacha20/chacha20.c new file mode 100644 index 0000000..ab5ef07 --- /dev/null +++ b/src/crypto/zinc/chacha20/chacha20.c @@ -0,0 +1,168 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. + * + * Implementation of the ChaCha20 stream cipher. + * + * Information: https://cr.yp.to/chacha.html + */ + +#include <zinc/chacha20.h> + +#include <linux/kernel.h> +#include <crypto/algapi.h> + +#ifndef HAVE_CHACHA20_ARCH_IMPLEMENTATION +void __init chacha20_fpu_init(void) +{ +} +static inline bool chacha20_arch(u8 *out, const u8 *in, const size_t len, + const u32 key[8], const u32 counter[4], + simd_context_t simd_context) +{ + return false; +} +static inline bool hchacha20_arch(u8 *derived_key, const u8 *nonce, + const u8 *key, simd_context_t simd_context) +{ + return false; +} +#endif + +#define EXPAND_32_BYTE_K 0x61707865U, 0x3320646eU, 0x79622d32U, 0x6b206574U + +#define QUARTER_ROUND(x, a, b, c, d) ( \ + x[a] += x[b], \ + x[d] = rol32((x[d] ^ x[a]), 16), \ + x[c] += x[d], \ + x[b] = rol32((x[b] ^ x[c]), 12), \ + x[a] += x[b], \ + x[d] = rol32((x[d] ^ x[a]), 8), \ + x[c] += x[d], \ + x[b] = rol32((x[b] ^ x[c]), 7) \ +) + +#define C(i, j) (i * 4 + j) + +#define DOUBLE_ROUND(x) ( \ + /* Column Round */ \ + QUARTER_ROUND(x, C(0, 0), C(1, 0), C(2, 0), C(3, 0)), \ + QUARTER_ROUND(x, C(0, 1), C(1, 1), C(2, 1), C(3, 1)), \ + QUARTER_ROUND(x, C(0, 2), C(1, 2), C(2, 2), C(3, 2)), \ + QUARTER_ROUND(x, C(0, 3), C(1, 3), C(2, 3), C(3, 3)), \ + /* Diagonal Round */ \ + QUARTER_ROUND(x, C(0, 0), C(1, 1), C(2, 2), C(3, 3)), \ + QUARTER_ROUND(x, C(0, 1), C(1, 2), C(2, 3), C(3, 0)), \ + QUARTER_ROUND(x, C(0, 2), C(1, 3), C(2, 0), C(3, 1)), \ + QUARTER_ROUND(x, C(0, 3), C(1, 0), C(2, 1), C(3, 2)) \ +) + +#define TWENTY_ROUNDS(x) ( \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x), \ + DOUBLE_ROUND(x) \ +) + +static void chacha20_block_generic(__le32 *stream, u32 *state) +{ + u32 x[CHACHA20_BLOCK_SIZE / sizeof(u32)]; + int i; + + for (i = 0; i < ARRAY_SIZE(x); ++i) + x[i] = state[i]; + + TWENTY_ROUNDS(x); + + for (i = 0; i < ARRAY_SIZE(x); ++i) + stream[i] = cpu_to_le32(x[i] + state[i]); + + ++state[12]; +} + +static void chacha20_generic(u8 *out, const u8 *in, u32 len, const u32 key[8], + const u32 counter[4]) +{ + __le32 buf[CHACHA20_BLOCK_SIZE / sizeof(__le32)]; + u32 x[] = { + EXPAND_32_BYTE_K, + key[0], key[1], key[2], key[3], + key[4], key[5], key[6], key[7], + counter[0], counter[1], counter[2], counter[3] + }; + + if (out != in) + memmove(out, in, len); + + while (len >= CHACHA20_BLOCK_SIZE) { + chacha20_block_generic(buf, x); + crypto_xor(out, (u8 *)buf, CHACHA20_BLOCK_SIZE); + len -= CHACHA20_BLOCK_SIZE; + out += CHACHA20_BLOCK_SIZE; + } + if (len) { + chacha20_block_generic(buf, x); + crypto_xor(out, (u8 *)buf, len); + } +} + +void chacha20(struct chacha20_ctx *state, u8 *dst, const u8 *src, u32 len, + simd_context_t simd_context) +{ + if (!chacha20_arch(dst, src, len, state->key, state->counter, + simd_context)) + chacha20_generic(dst, src, len, state->key, state->counter); + state->counter[0] += (len + 63) / 64; +} +EXPORT_SYMBOL(chacha20); + +static void hchacha20_generic(u8 derived_key[CHACHA20_KEY_SIZE], + const u8 nonce[HCHACHA20_NONCE_SIZE], + const u8 key[HCHACHA20_KEY_SIZE]) +{ + __le32 *out = (__force __le32 *)derived_key; + u32 x[] = { EXPAND_32_BYTE_K, + get_unaligned_le32(key + 0), + get_unaligned_le32(key + 4), + get_unaligned_le32(key + 8), + get_unaligned_le32(key + 12), + get_unaligned_le32(key + 16), + get_unaligned_le32(key + 20), + get_unaligned_le32(key + 24), + get_unaligned_le32(key + 28), + get_unaligned_le32(nonce + 0), + get_unaligned_le32(nonce + 4), + get_unaligned_le32(nonce + 8), + get_unaligned_le32(nonce + 12) + }; + + TWENTY_ROUNDS(x); + + out[0] = cpu_to_le32(x[0]); + out[1] = cpu_to_le32(x[1]); + out[2] = cpu_to_le32(x[2]); + out[3] = cpu_to_le32(x[3]); + out[4] = cpu_to_le32(x[12]); + out[5] = cpu_to_le32(x[13]); + out[6] = cpu_to_le32(x[14]); + out[7] = cpu_to_le32(x[15]); +} + +/* Derived key should be 32-bit aligned */ +void hchacha20(u8 derived_key[CHACHA20_KEY_SIZE], + const u8 nonce[HCHACHA20_NONCE_SIZE], + const u8 key[HCHACHA20_KEY_SIZE], simd_context_t simd_context) +{ + if (!hchacha20_arch(derived_key, nonce, key, simd_context)) + hchacha20_generic(derived_key, nonce, key); +} +/* Deliberately not EXPORT_SYMBOL'd, since there are few reasons why somebody + * should be using this directly, rather than via xchacha20. Revisit only in + * the unlikely event that somebody has a good reason to export this. + */ |