RTG-1339 Support post-quantum hybrid key exchange

Func spec: https://wiki.cfops.it/x/ZcBKHw

vendor/github.com/cloudflare/circl/simd/keccakf1600/f1600x.go

@@ -0,0 +1,149 @@
+// Package keccakf1600 provides a two and four-way Keccak-f[1600] permutation in parallel.
+//
+// Keccak-f[1600] is the permutation underlying several algorithms such as
+// Keccak, SHA3 and SHAKE. Running two or four permutations in parallel is
+// useful in some scenarios like in hash-based signatures.
+//
+// # Limitations
+//
+// Note that not all the architectures support SIMD instructions. This package
+// uses AVX2 instructions that are available in some AMD64 architectures
+// and  NEON instructions that are available in some ARM64 architectures.
+//
+// For those systems not supporting these, the package still provides the
+// expected functionality by means of a generic and slow implementation.
+// The recommendation is to beforehand verify IsEnabledX4() and IsEnabledX2()
+// to determine if the current system supports the SIMD implementation.
+package keccakf1600
+
+import (
+	"unsafe"
+
+	"github.com/cloudflare/circl/internal/sha3"
+	"golang.org/x/sys/cpu"
+)
+
+// StateX4 contains state for the four-way permutation including the four
+// interleaved [25]uint64 buffers. Call Initialize() before use to initialize
+// and get a pointer to the interleaved buffer.
+type StateX4 struct {
+	// Go guarantees a to be aligned on 8 bytes, whereas we need it to be
+	// aligned on 32 bytes for bet performance.  Thus we leave some headroom
+	// to be able to move the start of the state.
+
+	// 4 x 25 uint64s for the interleaved states and three uint64s headroom
+	// to fix alignment.
+	a [103]uint64
+
+	// Offset into a that is 32 byte aligned.
+	offset int
+}
+
+// StateX2 contains state for the two-way permutation including the two
+// interleaved [25]uint64 buffers. Call Initialize() before use to initialize
+// and get a pointer to the interleaved buffer.
+type StateX2 struct {
+	// Go guarantees a to be aligned on 8 bytes, whereas we need it to be
+	// aligned on 32 bytes for bet performance.  Thus we leave some headroom
+	// to be able to move the start of the state.
+
+	// 2 x 25 uint64s for the interleaved states and three uint64s headroom
+	// to fix alignment.
+	a [53]uint64
+
+	// Offset into a that is 32 byte aligned.
+	offset int
+}
+
+// IsEnabledX4 returns true if the architecture supports a four-way SIMD
+// implementation provided in this package.
+func IsEnabledX4() bool { return cpu.X86.HasAVX2 }
+
+// IsEnabledX2 returns true if the architecture supports a two-way SIMD
+// implementation provided in this package.
+func IsEnabledX2() bool {
+	// After Go 1.16 the flag cpu.ARM64.HasSHA3 is no longer exposed.
+	return false
+}
+
+// Initialize the state and returns the buffer on which the four permutations
+// will act: a uint64 slice of length 100.  The first permutation will act
+// on {a[0], a[4], ..., a[96]}, the second on {a[1], a[5], ..., a[97]}, etc.
+func (s *StateX4) Initialize() []uint64 {
+	rp := unsafe.Pointer(&s.a[0])
+
+	// uint64s are always aligned by a multiple of 8.  Compute the remainder
+	// of the address modulo 32 divided by 8.
+	rem := (int(uintptr(rp)&31) >> 3)
+
+	if rem != 0 {
+		s.offset = 4 - rem
+	}
+
+	// The slice we return will be aligned on 32 byte boundary.
+	return s.a[s.offset : s.offset+100]
+}
+
+// Initialize the state and returns the buffer on which the two permutations
+// will act: a uint64 slice of length 50.  The first permutation will act
+// on {a[0], a[2], ..., a[48]} and the second on {a[1], a[3], ..., a[49]}.
+func (s *StateX2) Initialize() []uint64 {
+	rp := unsafe.Pointer(&s.a[0])
+
+	// uint64s are always aligned by a multiple of 8.  Compute the remainder
+	// of the address modulo 32 divided by 8.
+	rem := (int(uintptr(rp)&31) >> 3)
+
+	if rem != 0 {
+		s.offset = 4 - rem
+	}
+
+	// The slice we return will be aligned on 32 byte boundary.
+	return s.a[s.offset : s.offset+50]
+}
+
+// Permute performs the four parallel Keccak-f[1600]s interleaved on the slice
+// returned from Initialize().
+func (s *StateX4) Permute() {
+	if IsEnabledX4() {
+		permuteSIMDx4(s.a[s.offset:])
+	} else {
+		permuteScalarX4(s.a[s.offset:]) // A slower generic implementation.
+	}
+}
+
+// Permute performs the two parallel Keccak-f[1600]s interleaved on the slice
+// returned from Initialize().
+func (s *StateX2) Permute() {
+	if IsEnabledX2() {
+		permuteSIMDx2(s.a[s.offset:])
+	} else {
+		permuteScalarX2(s.a[s.offset:]) // A slower generic implementation.
+	}
+}
+
+func permuteScalarX4(a []uint64) {
+	var buf [25]uint64
+	for i := 0; i < 4; i++ {
+		for j := 0; j < 25; j++ {
+			buf[j] = a[4*j+i]
+		}
+		sha3.KeccakF1600(&buf)
+		for j := 0; j < 25; j++ {
+			a[4*j+i] = buf[j]
+		}
+	}
+}
+
+func permuteScalarX2(a []uint64) {
+	var buf [25]uint64
+	for i := 0; i < 2; i++ {
+		for j := 0; j < 25; j++ {
+			buf[j] = a[2*j+i]
+		}
+		sha3.KeccakF1600(&buf)
+		for j := 0; j < 25; j++ {
+			a[2*j+i] = buf[j]
+		}
+	}
+}