feat:KMS support for BBS+ keys: create Tink key templates

closes hyperledger-archives#2548

Signed-off-by: Baha Shaaban <baha.shaaban@securekey.com>

pkg/crypto/tinkcrypto/primitive/bbs/bbs.go

@@ -12,7 +12,81 @@ SPDX-License-Identifier: Apache-2.0
 //  * Signer for signing a list of messages with a private key
 //
 //  * Verifier for verifying a signature against a list of messages, deriving a proof from a signature for a given
-//    message and verifying such derived proof.
+//    set of sub messages and verifying such derived proof.
+//
+//
+// Example:
+//
+//  package main
+//
+//  import (
+//      "bytes"
+//
+//      "github.com/google/tink/go/keyset"
+//
+//      "github.com/hyperledger/aries-framework-go/pkg/crypto/tinkcrypto/primitive/bbs"
+//  )
+//
+//  func main() {
+//      // create signer keyset handle
+//      kh, err := keyset.NewHandle(bbs.BLS12381G2KeyTemplate())
+//      if err != nil {
+//          //handle error
+//      }
+//
+//      // extract signer public keyset handle and key for signature verification and proof derivation/verification
+//      verKH, err := kh.Public()
+//      if err != nil {
+//          //handle error
+//      }
+//
+//		// finally get the BBS+ signing primitive from the private key handle created above
+//		s:= bbs.NewSigner(kh)
+//
+//		// create a message to be signed
+//		messages := [][]byte{[]byte("message 1"), []byte("message 2"), []byte("message 3"), []byte("message 4")}
+//
+//		// and now sign using s
+//      sig, err = s.Sign(messages)
+//      if err != nil {
+//          // handle error
+//      }
+//
+//		// to verify, get the BBS+ verification primitive from the public key handle created earlier above
+//      v := bbs.NewVerifier(verKH)
+//
+//		// and verify signature
+//      pt, err := v.Verify(messages, sig)
+//      if err != nil {
+//          // handle error
+//      }
+//
+//		// to derive a proof from the bbs signature, create the indices of the messages to be revealed by the proof
+//		revealedIndexes := []int{0, 2}
+//
+//		// and a nonce
+//		nonce := make([]byte, 10)
+//
+//		_, err = rand.Read(nonce)
+//      if err != nil {
+//          // handle error
+//      }
+//
+//		// then derive a proof for messages at index 0 and 2 as follows
+//		proof, err := verifier.DeriveProof(messages, sig, nonce, revealedIndexes)
+//      if err != nil {
+//          // handle error
+//      }
+//
+//		// create a copy of the revealed messages to the party that should only access messages at index 0 and 2
+//		revealedMsgs := [][]byte{messages[0], messages[2]}
+//
+//		// finally to verify the proof's authenticity for revealedMsgs, do the following
+//		err = verifier.VerifyProof(revealedMsgs, proof, nonce)
+//      if err != nil {
+//          // handle error
+//      }
+//  }
 package bbs
 
 import (

pkg/crypto/tinkcrypto/primitive/bbs/bbs_key_template.go

@@ -0,0 +1,42 @@
+/*
+Copyright SecureKey Technologies Inc. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package bbs
+
+import (
+	"github.com/golang/protobuf/proto"
+	commonpb "github.com/google/tink/go/proto/common_go_proto"
+	tinkpb "github.com/google/tink/go/proto/tink_go_proto"
+
+	bbspb "github.com/hyperledger/aries-framework-go/pkg/crypto/tinkcrypto/primitive/proto/bbs_go_proto"
+)
+
+// BLS12381G2KeyTemplate creates a Tink key template for BBS+ on BLS12-381 curve with G2 group.
+func BLS12381G2KeyTemplate() *tinkpb.KeyTemplate {
+	return createKeyTemplate(bbspb.BBSCurveType_BLS12_381, bbspb.GroupField_G2, commonpb.HashType_SHA256)
+}
+
+// createKeyTemplate for BBS+ keys.
+func createKeyTemplate(curve bbspb.BBSCurveType, group bbspb.GroupField, hash commonpb.HashType) *tinkpb.KeyTemplate {
+	format := &bbspb.BBSKeyFormat{
+		Params: &bbspb.BBSParams{
+			HashType: hash,
+			Curve:    curve,
+			Group:    group,
+		},
+	}
+
+	serializedFormat, err := proto.Marshal(format)
+	if err != nil {
+		panic("failed to marshal BBSKeyFormat proto")
+	}
+
+	return &tinkpb.KeyTemplate{
+		TypeUrl:          bbsSignerKeyTypeURL,
+		Value:            serializedFormat,
+		OutputPrefixType: tinkpb.OutputPrefixType_RAW,
+	}
+}

pkg/crypto/tinkcrypto/primitive/bbs/bbs_key_template_test.go

@@ -0,0 +1,54 @@
+/*
+Copyright SecureKey Technologies Inc. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package bbs
+
+import (
+	"crypto/rand"
+	"testing"
+
+	"github.com/google/tink/go/keyset"
+	"github.com/stretchr/testify/require"
+)
+
+func TestBBSKeyTemplateSuccess(t *testing.T) {
+	kt := BLS12381G2KeyTemplate()
+
+	kh, err := keyset.NewHandle(kt)
+	require.NoError(t, err)
+
+	pubKH, err := kh.Public()
+	require.NoError(t, err)
+
+	// now test the BBS primitives with these keyset handles
+	signer, err := NewSigner(kh)
+	require.NoError(t, err)
+
+	messages := [][]byte{[]byte("msg abc"), []byte("msg def"), []byte("msg ghi")}
+
+	sig, err := signer.Sign(messages)
+	require.NoError(t, err)
+
+	verifier, err := NewVerifier(pubKH)
+	require.NoError(t, err)
+
+	err = verifier.Verify(messages, sig)
+	require.NoError(t, err)
+
+	revealedIndexes := []int{1, 2}
+	nonce := make([]byte, 10)
+
+	_, err = rand.Read(nonce)
+	require.NoError(t, err)
+
+	proof, err := verifier.DeriveProof(messages, sig, nonce, revealedIndexes)
+	require.NoError(t, err)
+
+	revealedMsgs := [][]byte{messages[1], messages[2]}
+
+	err = verifier.VerifyProof(revealedMsgs, proof, nonce)
+	require.NoError(t, err)
+}

pkg/crypto/tinkcrypto/primitive/bbs/bbs_signer_key_manager.go

@@ -121,6 +121,7 @@ func (km *bbsSignerKeyManager) NewKey(serializedKeyFormat []byte) (proto.Message
 		KeyValue: privKeyBytes,
 		PublicKey: &bbspb.BBSPublicKey{
 			Version:  bbsSignerKeyVersion,
+			Params:   keyFormat.Params,
 			KeyValue: pubKeyBytes,
 		},
 	}, nil