// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// HERMETIC NOTE: The randen_hwaes target must not introduce duplicate
// symbols from arbitrary system and other headers, since it may be built
// with different flags from other targets, using different levels of
// optimization, potentially introducing ODR violations.
#include "absl/random/internal/randen_hwaes.h"
#include <cstdint>
#include <cstring>
#include "absl/base/attributes.h"
#include "absl/random/internal/platform.h"
#include "absl/random/internal/randen_traits.h"
// ABSL_RANDEN_HWAES_IMPL indicates whether this file will contain
// a hardware accelerated implementation of randen, or whether it
// will contain stubs that exit the process.
#if defined(ABSL_ARCH_X86_64) || defined(ABSL_ARCH_X86_32)
// The platform.h directives are sufficient to indicate whether
// we should build accelerated implementations for x86.
#if (ABSL_HAVE_ACCELERATED_AES || ABSL_RANDOM_INTERNAL_AES_DISPATCH)
#define ABSL_RANDEN_HWAES_IMPL 1
#endif
#elif defined(ABSL_ARCH_PPC)
// The platform.h directives are sufficient to indicate whether
// we should build accelerated implementations for PPC.
//
// NOTE: This has mostly been tested on 64-bit Power variants,
// and not embedded cpus such as powerpc32-8540
#if ABSL_HAVE_ACCELERATED_AES
#define ABSL_RANDEN_HWAES_IMPL 1
#endif
#elif defined(ABSL_ARCH_ARM) || defined(ABSL_ARCH_AARCH64)
// ARM is somewhat more complicated. We might support crypto natively...
#if ABSL_HAVE_ACCELERATED_AES || \
(defined(__ARM_NEON) && defined(__ARM_FEATURE_CRYPTO))
#define ABSL_RANDEN_HWAES_IMPL 1
#elif ABSL_RANDOM_INTERNAL_AES_DISPATCH && !defined(__APPLE__) && \
(defined(__GNUC__) && __GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ > 9)
// ...or, on GCC, we can use an ASM directive to
// instruct the assember to allow crypto instructions.
#define ABSL_RANDEN_HWAES_IMPL 1
#define ABSL_RANDEN_HWAES_IMPL_CRYPTO_DIRECTIVE 1
#endif
#else
// HWAES is unsupported by these architectures / platforms:
// __myriad2__
// __mips__
//
// Other architectures / platforms are unknown.
//
// See the Abseil documentation on supported macros at:
// https://abseil.io/docs/cpp/platforms/macros
#endif
#if !defined(ABSL_RANDEN_HWAES_IMPL)
// No accelerated implementation is supported.
// The RandenHwAes functions are stubs that print an error and exit.
#include <cstdio>
#include <cstdlib>
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace random_internal {
// No accelerated implementation.
bool HasRandenHwAesImplementation() { return false; }
// NOLINTNEXTLINE
const void* RandenHwAes::GetKeys() {
// Attempted to dispatch to an unsupported dispatch target.
const int d = ABSL_RANDOM_INTERNAL_AES_DISPATCH;
fprintf(stderr, "AES Hardware detection failed (%d).\n", d);
exit(1);
return nullptr;
}
// NOLINTNEXTLINE
void RandenHwAes::Absorb(const void*, void*) {
// Attempted to dispatch to an unsupported dispatch target.
const int d = ABSL_RANDOM_INTERNAL_AES_DISPATCH;
fprintf(stderr, "AES Hardware detection failed (%d).\n", d);
exit(1);
}
// NOLINTNEXTLINE
void RandenHwAes::Generate(const void*, void*) {
// Attempted to dispatch to an unsupported dispatch target.
const int d = ABSL_RANDOM_INTERNAL_AES_DISPATCH;
fprintf(stderr, "AES Hardware detection failed (%d).\n", d);
exit(1);
}
} // namespace random_internal
ABSL_NAMESPACE_END
} // namespace absl
#else // defined(ABSL_RANDEN_HWAES_IMPL)
//
// Accelerated implementations are supported.
// We need the per-architecture includes and defines.
//
namespace {
using absl::random_internal::RandenTraits;
// Randen operates on 128-bit vectors.
struct alignas(16) u64x2 {
uint64_t data[2];
};
} // namespace
// TARGET_CRYPTO defines a crypto attribute for each architecture.
//
// NOTE: Evaluate whether we should eliminate ABSL_TARGET_CRYPTO.
#if (defined(__clang__) || defined(__GNUC__))
#if defined(ABSL_ARCH_X86_64) || defined(ABSL_ARCH_X86_32)
#define ABSL_TARGET_CRYPTO __attribute__((target("aes")))
#elif defined(ABSL_ARCH_PPC)
#define ABSL_TARGET_CRYPTO __attribute__((target("crypto")))
#else
#define ABSL_TARGET_CRYPTO
#endif
#else
#define ABSL_TARGET_CRYPTO
#endif
#if defined(ABSL_ARCH_PPC)
// NOTE: Keep in mind that PPC can operate in little-endian or big-endian mode,
// however the PPC altivec vector registers (and thus the AES instructions)
// always operate in big-endian mode.
#include <altivec.h>
// <altivec.h> #defines vector __vector; in C++, this is bad form.
#undef vector
#undef bool
// Rely on the PowerPC AltiVec vector operations for accelerated AES
// instructions. GCC support of the PPC vector types is described in:
// https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/PowerPC-AltiVec_002fVSX-Built-in-Functions.html
//
// Already provides operator^=.
using Vector128 = __vector unsigned long long; // NOLINT(runtime/int)
namespace {
inline ABSL_TARGET_CRYPTO Vector128 ReverseBytes(const Vector128& v) {
// Reverses the bytes of the vector.
const __vector unsigned char perm = {15, 14, 13, 12, 11, 10, 9, 8,
7, 6, 5, 4, 3, 2, 1, 0};
return vec_perm(v, v, perm);
}
// WARNING: these load/store in native byte order. It is OK to load and then
// store an unchanged vector, but interpreting the bits as a number or input
// to AES will have undefined results.
inline ABSL_TARGET_CRYPTO Vector128 Vector128Load(const void* from) {
return vec_vsx_ld(0, reinterpret_cast<const Vector128*>(from));
}
inline ABSL_TARGET_CRYPTO void Vector128Store(const Vector128& v, void* to) {
vec_vsx_st(v, 0, reinterpret_cast<Vector128*>(to));
}
// One round of AES. "round_key" is a public constant for breaking the
// symmetry of AES (ensures previously equal columns differ afterwards).
inline ABSL_TARGET_CRYPTO Vector128 AesRound(const Vector128& state,
const Vector128& round_key) {
return Vector128(__builtin_crypto_vcipher(state, round_key));
}
// Enables native loads in the round loop by pre-swapping.
inline ABSL_TARGET_CRYPTO void SwapEndian(u64x2* state) {
for (uint32_t block = 0; block < RandenTraits::kFeistelBlocks; ++block) {
Vector128Store(ReverseBytes(Vector128Load(state + block)), state + block);
}
}
} // namespace
#elif defined(ABSL_ARCH_ARM) || defined(ABSL_ARCH_AARCH64)
// This asm directive will cause the file to be compiled with crypto extensions
// whether or not the cpu-architecture supports it.
#if ABSL_RANDEN_HWAES_IMPL_CRYPTO_DIRECTIVE
asm(".arch_extension crypto\n");
// Override missing defines.
#if !defined(__ARM_NEON)
#define __ARM_NEON 1
#endif
#if !defined(__ARM_FEATURE_CRYPTO)
#define __ARM_FEATURE_CRYPTO 1
#endif
#endif
// Rely on the ARM NEON+Crypto advanced simd types, defined in <arm_neon.h>.
// uint8x16_t is the user alias for underlying __simd128_uint8_t type.
// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0073a/IHI0073A_arm_neon_intrinsics_ref.pdf
//
// <arm_neon> defines the following
//
// typedef __attribute__((neon_vector_type(16))) uint8_t uint8x16_t;
// typedef __attribute__((neon_vector_type(16))) int8_t int8x16_t;
// typedef __attribute__((neon_polyvector_type(16))) int8_t poly8x16_t;
//
// vld1q_v
// vst1q_v
// vaeseq_v
// vaesmcq_v
#include <arm_neon.h>
// Already provides operator^=.
using Vector128 = uint8x16_t;
namespace {
inline ABSL_TARGET_CRYPTO Vector128 Vector128Load(const void* from) {
return vld1q_u8(reinterpret_cast<const uint8_t*>(from));
}
inline ABSL_TARGET_CRYPTO void Vector128Store(const Vector128& v, void* to) {
vst1q_u8(reinterpret_cast<uint8_t*>(to), v);
}
// One round of AES. "round_key" is a public constant for breaking the
// symmetry of AES (ensures previously equal columns differ afterwards).
inline ABSL_TARGET_CRYPTO Vector128 AesRound(const Vector128& state,
const Vector128& round_key) {
// It is important to always use the full round function - omitting the
// final MixColumns reduces security [https://eprint.iacr.org/2010/041.pdf]
// and does not help because we never decrypt.
//
// Note that ARM divides AES instructions differently than x86 / PPC,
// And we need to skip the first AddRoundKey step and add an extra
// AddRoundKey step to the end. Lucky for us this is just XOR.
return vaesmcq_u8(vaeseq_u8(state, uint8x16_t{})) ^ round_key;
}
inline ABSL_TARGET_CRYPTO void SwapEndian(void*) {}
} // namespace
#elif defined(ABSL_ARCH_X86_64) || defined(ABSL_ARCH_X86_32)
// On x86 we rely on the aesni instructions
#include <wmmintrin.h>
namespace {
// Vector128 class is only wrapper for __m128i, benchmark indicates that it's
// faster than using __m128i directly.
class Vector128 {
public:
// Convert from/to intrinsics.
inline explicit Vector128(const __m128i& Vector128) : data_(Vector128) {}
inline __m128i data() const { return data_; }
inline Vector128& operator^=(const Vector128& other) {
data_ = _mm_xor_si128(data_, other.data());
return *this;
}
private:
__m128i data_;
};
inline ABSL_TARGET_CRYPTO Vector128 Vector128Load(const void* from) {
return Vector128(_mm_load_si128(reinterpret_cast<const __m128i*>(from)));
}
inline ABSL_TARGET_CRYPTO void Vector128Store(const Vector128& v, void* to) {
_mm_store_si128(reinterpret_cast<__m128i*>(to), v.data());
}
// One round of AES. "round_key" is a public constant for breaking the
// symmetry of AES (ensures previously equal columns differ afterwards).
inline ABSL_TARGET_CRYPTO Vector128 AesRound(const Vector128& state,
const Vector128& round_key) {
// It is important to always use the full round function - omitting the
// final MixColumns reduces security [https://eprint.iacr.org/2010/041.pdf]
// and does not help because we never decrypt.
return Vector128(_mm_aesenc_si128(state.data(), round_key.data()));
}
inline ABSL_TARGET_CRYPTO void SwapEndian(void*) {}
} // namespace
#endif
#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunknown-pragmas"
#endif
// At this point, all of the platform-specific features have been defined /
// implemented.
//
// REQUIRES: using Vector128 = ...
// REQUIRES: Vector128 Vector128Load(void*) {...}
// REQUIRES: void Vector128Store(Vector128, void*) {...}
// REQUIRES: Vector128 AesRound(Vector128, Vector128) {...}
// REQUIRES: void SwapEndian(uint64_t*) {...}
//
// PROVIDES: absl::random_internal::RandenHwAes::Absorb
// PROVIDES: absl::random_internal::RandenHwAes::Generate
namespace {
// Block shuffles applies a shuffle to the entire state between AES rounds.
// Improved odd-even shuffle from "New criterion for diffusion property".
inline ABSL_TARGET_CRYPTO void BlockShuffle(u64x2* state) {
static_assert(RandenTraits::kFeistelBlocks == 16,
"Expecting 16 FeistelBlocks.");
constexpr size_t shuffle[RandenTraits::kFeistelBlocks] = {
7, 2, 13, 4, 11, 8, 3, 6, 15, 0, 9, 10, 1, 14, 5, 12};
const Vector128 v0 = Vector128Load(state + shuffle[0]);
const Vector128 v1 = Vector128Load(state + shuffle[1]);
const Vector128 v2 = Vector128Load(state + shuffle[2]);
const Vector128 v3 = Vector128Load(state + shuffle[3]);
const Vector128 v4 = Vector128Load(state + shuffle[4]);
const Vector128 v5 = Vector128Load(state + shuffle[5]);
const Vector128 v6 = Vector128Load(state + shuffle[6]);
const Vector128 v7 = Vector128Load(state + shuffle[7]);
const Vector128 w0 = Vector128Load(state + shuffle[8]);
const Vector128 w1 = Vector128Load(state + shuffle[9]);
const Vector128 w2 = Vector128Load(state + shuffle[10]);
const Vector128 w3 = Vector128Load(state + shuffle[11]);
const Vector128 w4 = Vector128Load(state + shuffle[12]);
const Vector128 w5 = Vector128Load(state + shuffle[13]);
const Vector128 w6 = Vector128Load(state + shuffle[14]);
const Vector128 w7 = Vector128Load(state + shuffle[15]);
Vector128Store(v0, state + 0);
Vector128Store(v1, state + 1);
Vector128Store(v2, state + 2);
Vector128Store(v3, state + 3);
Vector128Store(v4, state + 4);
Vector128Store(v5, state + 5);
Vector128Store(v6, state + 6);
Vector128Store(v7, state + 7);
Vector128Store(w0, state + 8);
Vector128Store(w1, state + 9);
Vector128Store(w2, state + 10);
Vector128Store(w3, state + 11);
Vector128Store(w4, state + 12);
Vector128Store(w5, state + 13);
Vector128Store(w6, state + 14);
Vector128Store(w7, state + 15);
}
// Feistel round function using two AES subrounds. Very similar to F()
// from Simpira v2, but with independent subround keys. Uses 17 AES rounds
// per 16 bytes (vs. 10 for AES-CTR). Computing eight round functions in
// parallel hides the 7-cycle AESNI latency on HSW. Note that the Feistel
// XORs are 'free' (included in the second AES instruction).
inline ABSL_TARGET_CRYPTO const u64x2* FeistelRound(
u64x2* state, const u64x2* ABSL_RANDOM_INTERNAL_RESTRICT keys) {
static_assert(RandenTraits::kFeistelBlocks == 16,
"Expecting 16 FeistelBlocks.");
// MSVC does a horrible job at unrolling loops.
// So we unroll the loop by hand to improve the performance.
const Vector128 s0 = Vector128Load(state + 0);
const Vector128 s1 = Vector128Load(state + 1);
const Vector128 s2 = Vector128Load(state + 2);
const Vector128 s3 = Vector128Load(state + 3);
const Vector128 s4 = Vector128Load(state + 4);
const Vector128 s5 = Vector128Load(state + 5);
const Vector128 s6 = Vector128Load(state + 6);
const Vector128 s7 = Vector128Load(state + 7);
const Vector128 s8 = Vector128Load(state + 8);
const Vector128 s9 = Vector128Load(state + 9);
const Vector128 s10 = Vector128Load(state + 10);
const Vector128 s11 = Vector128Load(state + 11);
const Vector128 s12 = Vector128Load(state + 12);
const Vector128 s13 = Vector128Load(state + 13);
const Vector128 s14 = Vector128Load(state + 14);
const Vector128 s15 = Vector128Load(state + 15);
// Encode even blocks with keys.
const Vector128 e0 = AesRound(s0, Vector128Load(keys + 0));
const Vector128 e2 = AesRound(s2, Vector128Load(keys + 1));
const Vector128 e4 = AesRound(s4, Vector128Load(keys + 2));
const Vector128 e6 = AesRound(s6, Vector128Load(keys + 3));
const Vector128 e8 = AesRound(s8, Vector128Load(keys + 4));
const Vector128 e10 = AesRound(s10, Vector128Load(keys + 5));
const Vector128 e12 = AesRound(s12, Vector128Load(keys + 6));
const Vector128 e14 = AesRound(s14, Vector128Load(keys + 7));
// Encode odd blocks with even output from above.
const Vector128 o1 = AesRound(e0, s1);
const Vector128 o3 = AesRound(e2, s3);
const Vector128 o5 = AesRound(e4, s5);
const Vector128 o7 = AesRound(e6, s7);
const Vector128 o9 = AesRound(e8, s9);
const Vector128 o11 = AesRound(e10, s11);
const Vector128 o13 = AesRound(e12, s13);
const Vector128 o15 = AesRound(e14, s15);
// Store odd blocks. (These will be shuffled later).
Vector128Store(o1, state + 1);
Vector128Store(o3, state + 3);
Vector128Store(o5, state + 5);
Vector128Store(o7, state + 7);
Vector128Store(o9, state + 9);
Vector128Store(o11, state + 11);
Vector128Store(o13, state + 13);
Vector128Store(o15, state + 15);
return keys + 8;
}
// Cryptographic permutation based via type-2 Generalized Feistel Network.
// Indistinguishable from ideal by chosen-ciphertext adversaries using less than
// 2^64 queries if the round function is a PRF. This is similar to the b=8 case
// of Simpira v2, but more efficient than its generic construction for b=16.
inline ABSL_TARGET_CRYPTO void Permute(
u64x2* state, const u64x2* ABSL_RANDOM_INTERNAL_RESTRICT keys) {
// (Successfully unrolled; the first iteration jumps into the second half)
#ifdef __clang__
#pragma clang loop unroll_count(2)
#endif
for (size_t round = 0; round < RandenTraits::kFeistelRounds; ++round) {
keys = FeistelRound(state, keys);
BlockShuffle(state);
}
}
} // namespace
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace random_internal {
bool HasRandenHwAesImplementation() { return true; }
const void* ABSL_TARGET_CRYPTO RandenHwAes::GetKeys() {
// Round keys for one AES per Feistel round and branch.
// The canonical implementation uses first digits of Pi.
#if defined(ABSL_ARCH_PPC)
return kRandenRoundKeysBE;
#else
return kRandenRoundKeys;
#endif
}
// NOLINTNEXTLINE
void ABSL_TARGET_CRYPTO RandenHwAes::Absorb(const void* seed_void,
void* state_void) {
static_assert(RandenTraits::kCapacityBytes / sizeof(Vector128) == 1,
"Unexpected Randen kCapacityBlocks");
static_assert(RandenTraits::kStateBytes / sizeof(Vector128) == 16,
"Unexpected Randen kStateBlocks");
auto* state =
reinterpret_cast<u64x2 * ABSL_RANDOM_INTERNAL_RESTRICT>(state_void);
const auto* seed =
reinterpret_cast<const u64x2 * ABSL_RANDOM_INTERNAL_RESTRICT>(seed_void);
Vector128 b1 = Vector128Load(state + 1);
b1 ^= Vector128Load(seed + 0);
Vector128Store(b1, state + 1);
Vector128 b2 = Vector128Load(state + 2);
b2 ^= Vector128Load(seed + 1);
Vector128Store(b2, state + 2);
Vector128 b3 = Vector128Load(state + 3);
b3 ^= Vector128Load(seed + 2);
Vector128Store(b3, state + 3);
Vector128 b4 = Vector128Load(state + 4);
b4 ^= Vector128Load(seed + 3);
Vector128Store(b4, state + 4);
Vector128 b5 = Vector128Load(state + 5);
b5 ^= Vector128Load(seed + 4);
Vector128Store(b5, state + 5);
Vector128 b6 = Vector128Load(state + 6);
b6 ^= Vector128Load(seed + 5);
Vector128Store(b6, state + 6);
Vector128 b7 = Vector128Load(state + 7);
b7 ^= Vector128Load(seed + 6);
Vector128Store(b7, state + 7);
Vector128 b8 = Vector128Load(state + 8);
b8 ^= Vector128Load(seed + 7);
Vector128Store(b8, state + 8);
Vector128 b9 = Vector128Load(state + 9);
b9 ^= Vector128Load(seed + 8);
Vector128Store(b9, state + 9);
Vector128 b10 = Vector128Load(state + 10);
b10 ^= Vector128Load(seed + 9);
Vector128Store(b10, state + 10);
Vector128 b11 = Vector128Load(state + 11);
b11 ^= Vector128Load(seed + 10);
Vector128Store(b11, state + 11);
Vector128 b12 = Vector128Load(state + 12);
b12 ^= Vector128Load(seed + 11);
Vector128Store(b12, state + 12);
Vector128 b13 = Vector128Load(state + 13);
b13 ^= Vector128Load(seed + 12);
Vector128Store(b13, state + 13);
Vector128 b14 = Vector128Load(state + 14);
b14 ^= Vector128Load(seed + 13);
Vector128Store(b14, state + 14);
Vector128 b15 = Vector128Load(state + 15);
b15 ^= Vector128Load(seed + 14);
Vector128Store(b15, state + 15);
}
// NOLINTNEXTLINE
void ABSL_TARGET_CRYPTO RandenHwAes::Generate(const void* keys_void,
void* state_void) {
static_assert(RandenTraits::kCapacityBytes == sizeof(Vector128),
"Capacity mismatch");
auto* state = reinterpret_cast<u64x2*>(state_void);
const auto* keys = reinterpret_cast<const u64x2*>(keys_void);
const Vector128 prev_inner = Vector128Load(state);
SwapEndian(state);
Permute(state, keys);
SwapEndian(state);
// Ensure backtracking resistance.
Vector128 inner = Vector128Load(state);
inner ^= prev_inner;
Vector128Store(inner, state);
}
#ifdef __clang__
#pragma clang diagnostic pop
#endif
} // namespace random_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // (ABSL_RANDEN_HWAES_IMPL)
