fix: reference /enc/ keys in keyAgreement section of DID doc (#146)

fixes #145

src/__tests__/resolver.test.ts

@@ -541,6 +541,7 @@ describe('ethrResolver', () => {
           ],
           authentication: [`${keyAgrDid}#controller`],
           assertionMethod: [`${keyAgrDid}#controller`, `${keyAgrDid}#delegate-1`],
+          keyAgreement: [`${keyAgrDid}#delegate-1`]
         })
       })
     })

src/resolver.ts

@@ -132,13 +132,15 @@ export class EthrDidResolver {
     let controller = address
 
     const authentication = [`${did}#controller`]
+    const keyAgreement: string[] = []
 
     let versionId = 0
     let nextVersionId = Number.POSITIVE_INFINITY
     let deactivated = false
     let delegateCount = 0
     let serviceCount = 0
     const auth: Record<string, string> = {}
+    const keyAgreementRefs: Record<string, string> = {}
     const pks: Record<string, VerificationMethod> = {}
     const services: Record<string, ServiceEndpoint> = {}
     for (const event of history) {
@@ -213,6 +215,8 @@ export class EthrDidResolver {
                 pks[eventIndex] = pk
                 if (match[4] === 'sigAuth') {
                   auth[eventIndex] = pk.id
+                } else if (match[4] === 'enc') {
+                  keyAgreementRefs[eventIndex] = pk.id
                 }
                 break
               }
@@ -280,6 +284,9 @@ export class EthrDidResolver {
     if (Object.values(services).length > 0) {
       didDocument.service = Object.values(services)
     }
+    if (Object.values(keyAgreementRefs).length > 0) {
+      didDocument.keyAgreement = keyAgreement.concat(Object.values(keyAgreementRefs))
+    }
     didDocument.assertionMethod = [...(didDocument.verificationMethod?.map((pk) => pk.id) || [])]
 
     return deactivated