qemu/crypto/clmul.c
Richard Henderson 00f463b38a crypto: Add generic 64-bit carry-less multiply routine
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
2023-09-15 13:57:00 +00:00

112 lines
2.2 KiB
C

/*
* Carry-less multiply operations.
* SPDX-License-Identifier: GPL-2.0-or-later
*
* Copyright (C) 2023 Linaro, Ltd.
*/
#include "qemu/osdep.h"
#include "crypto/clmul.h"
uint64_t clmul_8x8_low(uint64_t n, uint64_t m)
{
uint64_t r = 0;
for (int i = 0; i < 8; ++i) {
uint64_t mask = (n & 0x0101010101010101ull) * 0xff;
r ^= m & mask;
m = (m << 1) & 0xfefefefefefefefeull;
n >>= 1;
}
return r;
}
static uint64_t clmul_8x4_even_int(uint64_t n, uint64_t m)
{
uint64_t r = 0;
for (int i = 0; i < 8; ++i) {
uint64_t mask = (n & 0x0001000100010001ull) * 0xffff;
r ^= m & mask;
n >>= 1;
m <<= 1;
}
return r;
}
uint64_t clmul_8x4_even(uint64_t n, uint64_t m)
{
n &= 0x00ff00ff00ff00ffull;
m &= 0x00ff00ff00ff00ffull;
return clmul_8x4_even_int(n, m);
}
uint64_t clmul_8x4_odd(uint64_t n, uint64_t m)
{
return clmul_8x4_even(n >> 8, m >> 8);
}
static uint64_t unpack_8_to_16(uint64_t x)
{
return (x & 0x000000ff)
| ((x & 0x0000ff00) << 8)
| ((x & 0x00ff0000) << 16)
| ((x & 0xff000000) << 24);
}
uint64_t clmul_8x4_packed(uint32_t n, uint32_t m)
{
return clmul_8x4_even_int(unpack_8_to_16(n), unpack_8_to_16(m));
}
uint64_t clmul_16x2_even(uint64_t n, uint64_t m)
{
uint64_t r = 0;
n &= 0x0000ffff0000ffffull;
m &= 0x0000ffff0000ffffull;
for (int i = 0; i < 16; ++i) {
uint64_t mask = (n & 0x0000000100000001ull) * 0xffffffffull;
r ^= m & mask;
n >>= 1;
m <<= 1;
}
return r;
}
uint64_t clmul_16x2_odd(uint64_t n, uint64_t m)
{
return clmul_16x2_even(n >> 16, m >> 16);
}
uint64_t clmul_32(uint32_t n, uint32_t m32)
{
uint64_t r = 0;
uint64_t m = m32;
for (int i = 0; i < 32; ++i) {
r ^= n & 1 ? m : 0;
n >>= 1;
m <<= 1;
}
return r;
}
Int128 clmul_64_gen(uint64_t n, uint64_t m)
{
uint64_t rl = 0, rh = 0;
/* Bit 0 can only influence the low 64-bit result. */
if (n & 1) {
rl = m;
}
for (int i = 1; i < 64; ++i) {
uint64_t mask = -((n >> i) & 1);
rl ^= (m << i) & mask;
rh ^= (m >> (64 - i)) & mask;
}
return int128_make128(rl, rh);
}