feat: SD-JWT Issuer: Add Holder Public Key Claim (JWK)

If the Issuer wants to enable Holder Binding, it MAY include a public key associated with the Holder, or a reference thereto. We use confirmation "cnf" claim to include raw public key by value in SD-JWT. In this first iteration of "cnf" claim we will use "jwk" confirmation method and include public key information in JWK format. Other confirmation methods such as "jwe", "kid" and "jku" may be implemented at later time (if required). Signed-off-by: Sandra Vrtikapa <[email protected]>
sandrask · Jan 11, 2023 · 7ae7729 · 7ae7729
1 parent c8f690f
commit 7ae7729
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Showing 3 changed files with 67 additions and 7 deletions.
diff --git a/pkg/doc/sdjwt/common/common.go b/pkg/doc/sdjwt/common/common.go
@@ -41,6 +41,8 @@ type Payload struct {
 	NotBefore *jwt.NumericDate `json:"nbf,omitempty"`
 	IssuedAt  *jwt.NumericDate `json:"iat,omitempty"`
 
+	CNF map[string]interface{} `json:"cnf,omitempty"`
+
 	SD    []string `json:"_sd,omitempty"`
 	SDAlg string   `json:"_sd_alg,omitempty"`
 }

diff --git a/pkg/doc/sdjwt/issuer/issuer.go b/pkg/doc/sdjwt/issuer/issuer.go
@@ -20,6 +20,7 @@ import (
 	"github.com/go-jose/go-jose/v3/jwt"
 
 	"github.com/hyperledger/aries-framework-go/pkg/doc/jose"
+	"github.com/hyperledger/aries-framework-go/pkg/doc/jose/jwk"
 	afgjwt "github.com/hyperledger/aries-framework-go/pkg/doc/jwt"
 	"github.com/hyperledger/aries-framework-go/pkg/doc/sdjwt/common"
 )
@@ -48,6 +49,8 @@ type newOpts struct {
 	NotBefore *jwt.NumericDate
 	IssuedAt  *jwt.NumericDate
 
+	HolderPublicKey *jwk.JWK
+
 	HashAlg crypto.Hash
 
 	jsonMarshal func(v interface{}) ([]byte, error)
@@ -108,6 +111,13 @@ func WithID(id string) NewOpt {
 	}
 }
 
+// WithHolderPublicKey is an option for SD-JWT payload.
+func WithHolderPublicKey(jwk *jwk.JWK) NewOpt {
+	return func(opts *newOpts) {
+		opts.HolderPublicKey = jwk
+	}
+}
+
 // WithHashAlgorithm is an option for hashing disclosures.
 func WithHashAlgorithm(alg crypto.Hash) NewOpt {
 	return func(opts *newOpts) {
@@ -162,23 +172,36 @@ func New(issuer string, claims interface{}, headers jose.Headers,
 		return nil, err
 	}
 
+	payload := createPayload(issuer, digests, nOpts)
+
+	signedJWT, err := afgjwt.NewSigned(payload, headers, signer)
+	if err != nil {
+		return nil, err
+	}
+
+	return &SelectiveDisclosureJWT{Disclosures: disclosures, SignedJWT: signedJWT}, nil
+}
+
+func createPayload(issuer string, digests []string, nOpts *newOpts) *common.Payload {
+	var cnf map[string]interface{}
+	if nOpts.HolderPublicKey != nil {
+		cnf = make(map[string]interface{})
+		cnf["jwk"] = nOpts.HolderPublicKey
+	}
+
 	payload := &common.Payload{
 		Issuer:    issuer,
 		ID:        nOpts.ID,
 		Subject:   nOpts.Subject,
 		IssuedAt:  nOpts.IssuedAt,
 		Expiry:    nOpts.Expiry,
 		NotBefore: nOpts.NotBefore,
+		CNF:       cnf,
 		SD:        digests,
 		SDAlg:     strings.ToLower(nOpts.HashAlg.String()),
 	}
 
-	signedJWT, err := afgjwt.NewSigned(payload, headers, signer)
-	if err != nil {
-		return nil, err
-	}
-
-	return &SelectiveDisclosureJWT{Disclosures: disclosures, SignedJWT: signedJWT}, nil
+	return payload
 }
 
 func createDigests(disclosures []string, nOpts *newOpts) ([]string, error) {

diff --git a/pkg/doc/sdjwt/issuer/issuer_test.go b/pkg/doc/sdjwt/issuer/issuer_test.go
@@ -23,6 +23,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/hyperledger/aries-framework-go/pkg/doc/jose"
+	"github.com/hyperledger/aries-framework-go/pkg/doc/jose/jwk/jwksupport"
 	afjwt "github.com/hyperledger/aries-framework-go/pkg/doc/jwt"
 	"github.com/hyperledger/aries-framework-go/pkg/doc/sdjwt/common"
 )
@@ -133,7 +134,6 @@ func TestNew(t *testing.T) {
 			WithNotBefore(jwt.NewNumericDate(notBefore)),
 			WithID("id"),
 			WithSubject("subject"),
-			// TODO: Audience ???
 			WithSaltFnc(generateSalt),
 			WithJSONMarshaller(json.Marshal),
 			WithHashAlgorithm(crypto.SHA256),
@@ -198,6 +198,41 @@ func TestNew(t *testing.T) {
 		}
 	})
 
+	t.Run("Create JWS with holder public key", func(t *testing.T) {
+		r := require.New(t)
+
+		pubKey, privKey, err := ed25519.GenerateKey(rand.Reader)
+		r.NoError(err)
+
+		_, holderPublicKey, err := ed25519.GenerateKey(rand.Reader)
+		require.NoError(t, err)
+
+		holderJWK, err := jwksupport.JWKFromKey(holderPublicKey)
+		require.NoError(t, err)
+
+		token, err := New(issuer, claims, nil, afjwt.NewEd25519Signer(privKey),
+			WithHolderPublicKey(holderJWK))
+		r.NoError(err)
+		combinedFormatForIssuance, err := token.Serialize(false)
+		require.NoError(t, err)
+
+		cfi := common.ParseCombinedFormatForIssuance(combinedFormatForIssuance)
+		require.Equal(t, 1, len(cfi.Disclosures))
+
+		var parsedClaims map[string]interface{}
+		err = verifyEd25519ViaGoJose(cfi.SDJWT, pubKey, &parsedClaims)
+		r.NoError(err)
+		require.NotEmpty(t, parsedClaims["cnf"])
+
+		parsedClaimsBytes, err := json.Marshal(parsedClaims)
+		require.NoError(t, err)
+
+		prettyJSON, err := prettyPrint(parsedClaimsBytes)
+		require.NoError(t, err)
+
+		fmt.Println(prettyJSON)
+	})
+
 	t.Run("error - create decoy disclosures failed", func(t *testing.T) {
 		r := require.New(t)