On Tue, Sep 18, 2018 at 06:16:29PM +0200, Jason A. Donenfeld wrote: > diff --git a/lib/zinc/chacha20/chacha20.c b/lib/zinc/chacha20/chacha20.c > new file mode 100644 > index 000000000000..3f00e1edd4c8 > --- /dev/null > +++ b/lib/zinc/chacha20/chacha20.c > @@ -0,0 +1,193 @@ > +/* SPDX-License-Identifier: MIT > + * > + * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@xxxxxxxxx>. 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 <linux/module.h> > +#include <linux/init.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) \ > +) Does this consistently perform as well as an implementation that organizes the operations such that the quarterrounds for all columns/diagonals are interleaved? As-is, there are tight dependencies in QUARTER_ROUND() (as well as in the existing chacha20_block() in lib/chacha20.c, for that matter), so we're heavily depending on the compiler to do the needed interleaving so as to not get potentially disastrous performance. Making it explicit could be a good idea. > + > +static void chacha20_block_generic(__le32 *stream, u32 *state) > +{ > + u32 x[CHACHA20_BLOCK_WORDS]; > + 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_WORDS]; > + 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); > + } > +} If crypto_xor_cpy() is used instead of crypto_xor(), and 'in' is incremented along with 'out', then the memmove() is not needed. - Eric
