| /* 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 |
| * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN |
| * 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(uint8_t Xi[16], const u128 Htable[16]) { |
| uint64_t swapped[2]; |
| swapped[0] = CRYPTO_load_u64_be(Xi + 8); |
| swapped[1] = CRYPTO_load_u64_be(Xi); |
| gcm_polyval_nohw(swapped, &Htable[0]); |
| CRYPTO_store_u64_be(Xi, swapped[1]); |
| CRYPTO_store_u64_be(Xi + 8, swapped[0]); |
| } |
| |
| void gcm_ghash_nohw(uint8_t Xi[16], const u128 Htable[16], const uint8_t *inp, |
| size_t len) { |
| uint64_t swapped[2]; |
| swapped[0] = CRYPTO_load_u64_be(Xi + 8); |
| swapped[1] = CRYPTO_load_u64_be(Xi); |
| |
| while (len >= 16) { |
| swapped[0] ^= CRYPTO_load_u64_be(inp + 8); |
| swapped[1] ^= CRYPTO_load_u64_be(inp); |
| gcm_polyval_nohw(swapped, &Htable[0]); |
| inp += 16; |
| len -= 16; |
| } |
| |
| CRYPTO_store_u64_be(Xi, swapped[1]); |
| CRYPTO_store_u64_be(Xi + 8, swapped[0]); |
| } |