ref: 2cdc6577ef8a251bf1740439cf5bfc47050dab41
dir: /third_party/boringssl/src/crypto/fipsmodule/modes/gcm_nohw.c/
/* Copyright (c) 2019, Google Inc.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <openssl/base.h>
#include "../../internal.h"
#include "internal.h"
#if !defined(BORINGSSL_HAS_UINT128) && defined(OPENSSL_SSE2)
#include <emmintrin.h>
#endif
// This file contains a constant-time implementation of GHASH based on the notes
// in https://bearssl.org/constanttime.html#ghash-for-gcm and the reduction
// algorithm described in
// https://crypto.stanford.edu/RealWorldCrypto/slides/gueron.pdf.
//
// Unlike the BearSSL notes, we use uint128_t in the 64-bit implementation. Our
// primary compilers (clang, clang-cl, and gcc) all support it. MSVC will run
// the 32-bit implementation, but we can use its intrinsics if necessary.
#if defined(BORINGSSL_HAS_UINT128)
static void gcm_mul64_nohw(uint64_t *out_lo, uint64_t *out_hi, uint64_t a,
uint64_t b) {
// One term every four bits means the largest term is 64/4 = 16, which barely
// overflows into the next term. Using one term every five bits would cost 25
// multiplications instead of 16. It is faster to mask off the bottom four
// bits of |a|, giving a largest term of 60/4 = 15, and apply the bottom bits
// separately.
uint64_t a0 = a & UINT64_C(0x1111111111111110);
uint64_t a1 = a & UINT64_C(0x2222222222222220);
uint64_t a2 = a & UINT64_C(0x4444444444444440);
uint64_t a3 = a & UINT64_C(0x8888888888888880);
uint64_t b0 = b & UINT64_C(0x1111111111111111);
uint64_t b1 = b & UINT64_C(0x2222222222222222);
uint64_t b2 = b & UINT64_C(0x4444444444444444);
uint64_t b3 = b & UINT64_C(0x8888888888888888);
uint128_t c0 = (a0 * (uint128_t)b0) ^ (a1 * (uint128_t)b3) ^
(a2 * (uint128_t)b2) ^ (a3 * (uint128_t)b1);
uint128_t c1 = (a0 * (uint128_t)b1) ^ (a1 * (uint128_t)b0) ^
(a2 * (uint128_t)b3) ^ (a3 * (uint128_t)b2);
uint128_t c2 = (a0 * (uint128_t)b2) ^ (a1 * (uint128_t)b1) ^
(a2 * (uint128_t)b0) ^ (a3 * (uint128_t)b3);
uint128_t c3 = (a0 * (uint128_t)b3) ^ (a1 * (uint128_t)b2) ^
(a2 * (uint128_t)b1) ^ (a3 * (uint128_t)b0);
// Multiply the bottom four bits of |a| with |b|.
uint64_t a0_mask = UINT64_C(0) - (a & 1);
uint64_t a1_mask = UINT64_C(0) - ((a >> 1) & 1);
uint64_t a2_mask = UINT64_C(0) - ((a >> 2) & 1);
uint64_t a3_mask = UINT64_C(0) - ((a >> 3) & 1);
uint128_t extra = (a0_mask & b) ^ ((uint128_t)(a1_mask & b) << 1) ^
((uint128_t)(a2_mask & b) << 2) ^
((uint128_t)(a3_mask & b) << 3);
*out_lo = (((uint64_t)c0) & UINT64_C(0x1111111111111111)) ^
(((uint64_t)c1) & UINT64_C(0x2222222222222222)) ^
(((uint64_t)c2) & UINT64_C(0x4444444444444444)) ^
(((uint64_t)c3) & UINT64_C(0x8888888888888888)) ^ ((uint64_t)extra);
*out_hi = (((uint64_t)(c0 >> 64)) & UINT64_C(0x1111111111111111)) ^
(((uint64_t)(c1 >> 64)) & UINT64_C(0x2222222222222222)) ^
(((uint64_t)(c2 >> 64)) & UINT64_C(0x4444444444444444)) ^
(((uint64_t)(c3 >> 64)) & UINT64_C(0x8888888888888888)) ^
((uint64_t)(extra >> 64));
}
#elif defined(OPENSSL_SSE2)
static __m128i gcm_mul32_nohw(uint32_t a, uint32_t b) {
// One term every four bits means the largest term is 32/4 = 8, which does not
// overflow into the next term.
__m128i aa = _mm_setr_epi32(a, 0, a, 0);
__m128i bb = _mm_setr_epi32(b, 0, b, 0);
__m128i a0a0 =
_mm_and_si128(aa, _mm_setr_epi32(0x11111111, 0, 0x11111111, 0));
__m128i a2a2 =
_mm_and_si128(aa, _mm_setr_epi32(0x44444444, 0, 0x44444444, 0));
__m128i b0b1 =
_mm_and_si128(bb, _mm_setr_epi32(0x11111111, 0, 0x22222222, 0));
__m128i b2b3 =
_mm_and_si128(bb, _mm_setr_epi32(0x44444444, 0, 0x88888888, 0));
__m128i c0c1 =
_mm_xor_si128(_mm_mul_epu32(a0a0, b0b1), _mm_mul_epu32(a2a2, b2b3));
__m128i c2c3 =
_mm_xor_si128(_mm_mul_epu32(a2a2, b0b1), _mm_mul_epu32(a0a0, b2b3));
__m128i a1a1 =
_mm_and_si128(aa, _mm_setr_epi32(0x22222222, 0, 0x22222222, 0));
__m128i a3a3 =
_mm_and_si128(aa, _mm_setr_epi32(0x88888888, 0, 0x88888888, 0));
__m128i b3b0 =
_mm_and_si128(bb, _mm_setr_epi32(0x88888888, 0, 0x11111111, 0));
__m128i b1b2 =
_mm_and_si128(bb, _mm_setr_epi32(0x22222222, 0, 0x44444444, 0));
c0c1 = _mm_xor_si128(c0c1, _mm_mul_epu32(a1a1, b3b0));
c0c1 = _mm_xor_si128(c0c1, _mm_mul_epu32(a3a3, b1b2));
c2c3 = _mm_xor_si128(c2c3, _mm_mul_epu32(a3a3, b3b0));
c2c3 = _mm_xor_si128(c2c3, _mm_mul_epu32(a1a1, b1b2));
c0c1 = _mm_and_si128(
c0c1, _mm_setr_epi32(0x11111111, 0x11111111, 0x22222222, 0x22222222));
c2c3 = _mm_and_si128(
c2c3, _mm_setr_epi32(0x44444444, 0x44444444, 0x88888888, 0x88888888));
c0c1 = _mm_xor_si128(c0c1, c2c3);
// c0 ^= c1
c0c1 = _mm_xor_si128(c0c1, _mm_srli_si128(c0c1, 8));
return c0c1;
}
static void gcm_mul64_nohw(uint64_t *out_lo, uint64_t *out_hi, uint64_t a,
uint64_t b) {
uint32_t a0 = a & 0xffffffff;
uint32_t a1 = a >> 32;
uint32_t b0 = b & 0xffffffff;
uint32_t b1 = b >> 32;
// Karatsuba multiplication.
__m128i lo = gcm_mul32_nohw(a0, b0);
__m128i hi = gcm_mul32_nohw(a1, b1);
__m128i mid = gcm_mul32_nohw(a0 ^ a1, b0 ^ b1);
mid = _mm_xor_si128(mid, lo);
mid = _mm_xor_si128(mid, hi);
__m128i ret = _mm_unpacklo_epi64(lo, hi);
mid = _mm_slli_si128(mid, 4);
mid = _mm_and_si128(mid, _mm_setr_epi32(0, 0xffffffff, 0xffffffff, 0));
ret = _mm_xor_si128(ret, mid);
memcpy(out_lo, &ret, 8);
memcpy(out_hi, ((char*)&ret) + 8, 8);
}
#else // !BORINGSSL_HAS_UINT128 && !OPENSSL_SSE2
static uint64_t gcm_mul32_nohw(uint32_t a, uint32_t b) {
// One term every four bits means the largest term is 32/4 = 8, which does not
// overflow into the next term.
uint32_t a0 = a & 0x11111111;
uint32_t a1 = a & 0x22222222;
uint32_t a2 = a & 0x44444444;
uint32_t a3 = a & 0x88888888;
uint32_t b0 = b & 0x11111111;
uint32_t b1 = b & 0x22222222;
uint32_t b2 = b & 0x44444444;
uint32_t b3 = b & 0x88888888;
uint64_t c0 = (a0 * (uint64_t)b0) ^ (a1 * (uint64_t)b3) ^
(a2 * (uint64_t)b2) ^ (a3 * (uint64_t)b1);
uint64_t c1 = (a0 * (uint64_t)b1) ^ (a1 * (uint64_t)b0) ^
(a2 * (uint64_t)b3) ^ (a3 * (uint64_t)b2);
uint64_t c2 = (a0 * (uint64_t)b2) ^ (a1 * (uint64_t)b1) ^
(a2 * (uint64_t)b0) ^ (a3 * (uint64_t)b3);
uint64_t c3 = (a0 * (uint64_t)b3) ^ (a1 * (uint64_t)b2) ^
(a2 * (uint64_t)b1) ^ (a3 * (uint64_t)b0);
return (c0 & UINT64_C(0x1111111111111111)) |
(c1 & UINT64_C(0x2222222222222222)) |
(c2 & UINT64_C(0x4444444444444444)) |
(c3 & UINT64_C(0x8888888888888888));
}
static void gcm_mul64_nohw(uint64_t *out_lo, uint64_t *out_hi, uint64_t a,
uint64_t b) {
uint32_t a0 = a & 0xffffffff;
uint32_t a1 = a >> 32;
uint32_t b0 = b & 0xffffffff;
uint32_t b1 = b >> 32;
// Karatsuba multiplication.
uint64_t lo = gcm_mul32_nohw(a0, b0);
uint64_t hi = gcm_mul32_nohw(a1, b1);
uint64_t mid = gcm_mul32_nohw(a0 ^ a1, b0 ^ b1) ^ lo ^ hi;
*out_lo = lo ^ (mid << 32);
*out_hi = hi ^ (mid >> 32);
}
#endif // BORINGSSL_HAS_UINT128
void gcm_init_nohw(u128 Htable[16], const uint64_t Xi[2]) {
// We implement GHASH in terms of POLYVAL, as described in RFC 8452. This
// avoids a shift by 1 in the multiplication, needed to account for bit
// reversal losing a bit after multiplication, that is,
// rev128(X) * rev128(Y) = rev255(X*Y).
//
// Per Appendix A, we run mulX_POLYVAL. Note this is the same transformation
// applied by |gcm_init_clmul|, etc. Note |Xi| has already been byteswapped.
//
// See also slide 16 of
// https://crypto.stanford.edu/RealWorldCrypto/slides/gueron.pdf
Htable[0].lo = Xi[1];
Htable[0].hi = Xi[0];
uint64_t carry = Htable[0].hi >> 63;
carry = 0u - carry;
Htable[0].hi <<= 1;
Htable[0].hi |= Htable[0].lo >> 63;
Htable[0].lo <<= 1;
// The irreducible polynomial is 1 + x^121 + x^126 + x^127 + x^128, so we
// conditionally add 0xc200...0001.
Htable[0].lo ^= carry & 1;
Htable[0].hi ^= carry & UINT64_C(0xc200000000000000);
// This implementation does not use the rest of |Htable|.
}
static void gcm_polyval_nohw(uint64_t Xi[2], const u128 *H) {
// Karatsuba multiplication. The product of |Xi| and |H| is stored in |r0|
// through |r3|. Note there is no byte or bit reversal because we are
// evaluating POLYVAL.
uint64_t r0, r1;
gcm_mul64_nohw(&r0, &r1, Xi[0], H->lo);
uint64_t r2, r3;
gcm_mul64_nohw(&r2, &r3, Xi[1], H->hi);
uint64_t mid0, mid1;
gcm_mul64_nohw(&mid0, &mid1, Xi[0] ^ Xi[1], H->hi ^ H->lo);
mid0 ^= r0 ^ r2;
mid1 ^= r1 ^ r3;
r2 ^= mid1;
r1 ^= mid0;
// Now we multiply our 256-bit result by x^-128 and reduce. |r2| and
// |r3| shifts into position and we must multiply |r0| and |r1| by x^-128. We
// have:
//
// 1 = x^121 + x^126 + x^127 + x^128
// x^-128 = x^-7 + x^-2 + x^-1 + 1
//
// This is the GHASH reduction step, but with bits flowing in reverse.
// The x^-7, x^-2, and x^-1 terms shift bits past x^0, which would require
// another reduction steps. Instead, we gather the excess bits, incorporate
// them into |r0| and |r1| and reduce once. See slides 17-19
// of https://crypto.stanford.edu/RealWorldCrypto/slides/gueron.pdf.
r1 ^= (r0 << 63) ^ (r0 << 62) ^ (r0 << 57);
// 1
r2 ^= r0;
r3 ^= r1;
// x^-1
r2 ^= r0 >> 1;
r2 ^= r1 << 63;
r3 ^= r1 >> 1;
// x^-2
r2 ^= r0 >> 2;
r2 ^= r1 << 62;
r3 ^= r1 >> 2;
// x^-7
r2 ^= r0 >> 7;
r2 ^= r1 << 57;
r3 ^= r1 >> 7;
Xi[0] = r2;
Xi[1] = r3;
}
void gcm_gmult_nohw(uint64_t Xi[2], const u128 Htable[16]) {
uint64_t swapped[2];
swapped[0] = CRYPTO_bswap8(Xi[1]);
swapped[1] = CRYPTO_bswap8(Xi[0]);
gcm_polyval_nohw(swapped, &Htable[0]);
Xi[0] = CRYPTO_bswap8(swapped[1]);
Xi[1] = CRYPTO_bswap8(swapped[0]);
}
void gcm_ghash_nohw(uint64_t Xi[2], const u128 Htable[16], const uint8_t *inp,
size_t len) {
uint64_t swapped[2];
swapped[0] = CRYPTO_bswap8(Xi[1]);
swapped[1] = CRYPTO_bswap8(Xi[0]);
while (len >= 16) {
uint64_t block[2];
OPENSSL_memcpy(block, inp, 16);
swapped[0] ^= CRYPTO_bswap8(block[1]);
swapped[1] ^= CRYPTO_bswap8(block[0]);
gcm_polyval_nohw(swapped, &Htable[0]);
inp += 16;
len -= 16;
}
Xi[0] = CRYPTO_bswap8(swapped[1]);
Xi[1] = CRYPTO_bswap8(swapped[0]);
}