Key agreement

helpers/crypto/crypto.go

@@ -12,8 +12,9 @@ import (
 )
 
 const (
-	DidPrefix = "did:knox:"
-	ProofType = "Ed25519VerificationKey2020"
+	DidPrefix        = "did:knox:"
+	ProofType        = "Ed25519VerificationKey2020"
+	KeyAgreementType = "X25519KeyAgreementKey2019"
 )
 
 var MultiCodecPrefix = []byte{0xed, 0x01}
@@ -34,6 +35,9 @@ type KeyPairs struct {
 
 	AssertionMethodPublicKey  string
 	AssertionMethodPrivateKey []byte
+
+	KeyAgreementPublicKey  string
+	KeyAgreementPrivateKey []byte
 }
 
 type cryptoManager struct {
@@ -72,6 +76,8 @@ func (c *cryptoManager) GenerateKeyPair(mnemonic string) (*KeyPairs, error) {
 		CapabilityDelegationPrivateKey: private,
 		AssertionMethodPublicKey:       encodedPublic,
 		AssertionMethodPrivateKey:      private,
+		KeyAgreementPublicKey:          encodedPublic,
+		KeyAgreementPrivateKey:         private,
 	}, nil
 
 }

helpers/did/did.go

@@ -54,6 +54,14 @@ func CreateDidDocument(kps *crypto.KeyPairs) *model.DidDocument {
 				PublicKeyMultibase: kps.AssertionMethodPublicKey,
 			},
 		},
+		KeyAgreement: []model.KeyMaterial{
+			{
+				Id:                 kps.GetVerificationMethod(signer.KeyAgreement),
+				Type:               crypto.KeyAgreementType,
+				Controller:         crypto.DidPrefix + kps.MasterPublicKey,
+				PublicKeyMultibase: kps.KeyAgreementPublicKey,
+			},
+		},
 	}
 }
 

model/model.go

@@ -41,6 +41,7 @@ type DidDocument struct {
 	CapabilityInvocation []KeyMaterial `json:"capabilityInvocation"`
 	CapabilityDelegation []KeyMaterial `json:"capabilityDelegation"`
 	AssertionMethod      []KeyMaterial `json:"assertionMethod"`
+	KeyAgreement         []KeyMaterial `json:"keyAgreement,omitempty"`
 }
 
 type AuthToken struct {

signer/signer.go

@@ -9,6 +9,7 @@ const (
 	CapabilityInvocation
 	CapabilityDelegation
 	AssertionMethod
+	KeyAgreement
 )
 
 func (vr VerificationRelation) String() string {
@@ -23,6 +24,8 @@ func (vr VerificationRelation) String() string {
 		return "capabilityDelegation"
 	case AssertionMethod:
 		return "associationMethod"
+	case KeyAgreement:
+		return "keyAgreement"
 	default:
 		return ""
 	}