Add KangarooTwelve as XOF

Author: bwesterb

README.md

@@ -74,6 +74,7 @@ go get -u github.com/cloudflare/circl
 #### XOF: eXtendable Output Functions
  - [FIPS 202](https://doi.org/10.6028/NIST.FIPS.202): SHAKE128 and SHAKE256
  - [BLAKE2X](https://www.blake2.net/blake2x.pdf): BLAKE2XB and BLAKE2XS
+ - [KangarooTwelve](https://keccak.team/kangarootwelve.html): KangarooTwelve
 
 #### Zero-knowledge Proofs
  - [Schnorr](./zk/dl): Prove knowledge of the Discrete Logarithm.

xof/k12/k12.go

@@ -79,6 +79,29 @@ func (s *State) Reset() {
 	s.chunk = 0
 }
 
+func (s *State) Clone() State {
+	stalk := s.stalk.Clone().(*sha3.State)
+	ret := State{
+		initialTodo: s.initialTodo,
+		stalk:       *stalk,
+		context:     s.context,
+		offset:      s.offset,
+		chunk:       s.chunk,
+		lanes:       s.lanes,
+	}
+
+	if s.leaf != nil {
+		ret.leaf = s.leaf.Clone().(*sha3.State)
+	}
+
+	if s.buf != nil {
+		ret.buf = make([]byte, len(s.buf))
+		copy(ret.buf, s.buf)
+	}
+
+	return ret
+}
+
 func Draft10Sum(hash []byte, msg []byte, c []byte) {
 	// TODO Tweak number of lanes depending on the length of the message
 	s := NewDraft10(c)

xof/xof.go

@@ -10,6 +10,8 @@ import (
 	"io"
 
 	"github.com/cloudflare/circl/internal/sha3"
+	"github.com/cloudflare/circl/xof/k12"
+
 	"golang.org/x/crypto/blake2b"
 	"golang.org/x/crypto/blake2s"
 )
@@ -38,6 +40,7 @@ const (
 	SHAKE256
 	BLAKE2XB
 	BLAKE2XS
+	K12D10
 )
 
 func (x ID) New() XOF {
@@ -54,6 +57,9 @@ func (x ID) New() XOF {
 	case BLAKE2XS:
 		x, _ := blake2s.NewXOF(blake2s.OutputLengthUnknown, nil)
 		return blake2xs{x}
+	case K12D10:
+		x := k12.NewDraft10([]byte{})
+		return k12d10{&x}
 	default:
 		panic("crypto: requested unavailable XOF function")
 	}
@@ -70,3 +76,10 @@ func (s blake2xb) Clone() XOF { return blake2xb{s.XOF.Clone()} }
 type blake2xs struct{ blake2s.XOF }
 
 func (s blake2xs) Clone() XOF { return blake2xs{s.XOF.Clone()} }
+
+type k12d10 struct{ *k12.State }
+
+func (s k12d10) Clone() XOF {
+	x := s.State.Clone()
+	return k12d10{&x}
+}

xof/xof_test.go

@@ -53,6 +53,12 @@ var allVectors = []vector{
 		out:    "0650cde4df888a06eada0f0fecb3c17594304b4a03fdd678182f27db1238b174",
 		outLen: 32,
 	},
+	{
+		id:     xof.K12D10,
+		in:     "The quick brown fox jumps over the lazy dog",
+		out:    "b4f249b4f77c58df170aa4d1723db1127d82f1d98d25ddda561ada459cd11a48",
+		outLen: 32,
+	},
 }
 
 func TestXof(t *testing.T) {