chore: migrate to gitea

vendor/golang.org/x/crypto/sha3/shake.go

@@ -0,0 +1,119 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package sha3
+
+import (
+	"crypto/sha3"
+	"hash"
+	"io"
+)
+
+// ShakeHash defines the interface to hash functions that support
+// arbitrary-length output. When used as a plain [hash.Hash], it
+// produces minimum-length outputs that provide full-strength generic
+// security.
+type ShakeHash interface {
+	hash.Hash
+
+	// Read reads more output from the hash; reading affects the hash's
+	// state. (ShakeHash.Read is thus very different from Hash.Sum.)
+	// It never returns an error, but subsequent calls to Write or Sum
+	// will panic.
+	io.Reader
+
+	// Clone returns a copy of the ShakeHash in its current state.
+	Clone() ShakeHash
+}
+
+// NewShake128 creates a new SHAKE128 variable-output-length ShakeHash.
+// Its generic security strength is 128 bits against all attacks if at
+// least 32 bytes of its output are used.
+func NewShake128() ShakeHash {
+	return &shakeWrapper{sha3.NewSHAKE128(), 32, false, sha3.NewSHAKE128}
+}
+
+// NewShake256 creates a new SHAKE256 variable-output-length ShakeHash.
+// Its generic security strength is 256 bits against all attacks if
+// at least 64 bytes of its output are used.
+func NewShake256() ShakeHash {
+	return &shakeWrapper{sha3.NewSHAKE256(), 64, false, sha3.NewSHAKE256}
+}
+
+// NewCShake128 creates a new instance of cSHAKE128 variable-output-length ShakeHash,
+// a customizable variant of SHAKE128.
+// N is used to define functions based on cSHAKE, it can be empty when plain cSHAKE is
+// desired. S is a customization byte string used for domain separation - two cSHAKE
+// computations on same input with different S yield unrelated outputs.
+// When N and S are both empty, this is equivalent to NewShake128.
+func NewCShake128(N, S []byte) ShakeHash {
+	return &shakeWrapper{sha3.NewCSHAKE128(N, S), 32, false, func() *sha3.SHAKE {
+		return sha3.NewCSHAKE128(N, S)
+	}}
+}
+
+// NewCShake256 creates a new instance of cSHAKE256 variable-output-length ShakeHash,
+// a customizable variant of SHAKE256.
+// N is used to define functions based on cSHAKE, it can be empty when plain cSHAKE is
+// desired. S is a customization byte string used for domain separation - two cSHAKE
+// computations on same input with different S yield unrelated outputs.
+// When N and S are both empty, this is equivalent to NewShake256.
+func NewCShake256(N, S []byte) ShakeHash {
+	return &shakeWrapper{sha3.NewCSHAKE256(N, S), 64, false, func() *sha3.SHAKE {
+		return sha3.NewCSHAKE256(N, S)
+	}}
+}
+
+// ShakeSum128 writes an arbitrary-length digest of data into hash.
+func ShakeSum128(hash, data []byte) {
+	h := NewShake128()
+	h.Write(data)
+	h.Read(hash)
+}
+
+// ShakeSum256 writes an arbitrary-length digest of data into hash.
+func ShakeSum256(hash, data []byte) {
+	h := NewShake256()
+	h.Write(data)
+	h.Read(hash)
+}
+
+// shakeWrapper adds the Size, Sum, and Clone methods to a sha3.SHAKE
+// to implement the ShakeHash interface.
+type shakeWrapper struct {
+	*sha3.SHAKE
+	outputLen int
+	squeezing bool
+	newSHAKE  func() *sha3.SHAKE
+}
+
+func (w *shakeWrapper) Read(p []byte) (n int, err error) {
+	w.squeezing = true
+	return w.SHAKE.Read(p)
+}
+
+func (w *shakeWrapper) Clone() ShakeHash {
+	s := w.newSHAKE()
+	b, err := w.MarshalBinary()
+	if err != nil {
+		panic(err) // unreachable
+	}
+	if err := s.UnmarshalBinary(b); err != nil {
+		panic(err) // unreachable
+	}
+	return &shakeWrapper{s, w.outputLen, w.squeezing, w.newSHAKE}
+}
+
+func (w *shakeWrapper) Size() int { return w.outputLen }
+
+func (w *shakeWrapper) Sum(b []byte) []byte {
+	if w.squeezing {
+		panic("sha3: Sum after Read")
+	}
+	out := make([]byte, w.outputLen)
+	// Clone the state so that we don't affect future Write calls.
+	s := w.Clone()
+	s.Read(out)
+	return append(b, out...)
+}