feat(utils): add 2 utility functions for inspecting ethr dids (#842)

* feat(utils): Add 2 utility functions for inspecting ethr dids

packages/utils/src/__tests__/did-utils.test.ts

@@ -0,0 +1,41 @@
+import { getChainIdForDidEthr, getEthereumAddress } from '../did-utils'
+
+describe('@veramo/utils did utils', () => {
+  it(`should return correct chainId for did:ethr`, () => {
+    expect(() => getChainIdForDidEthr({
+      'id': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51#controller',
+      'type': 'EcdsaSecp256k1RecoveryMethod2020',
+      'controller': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51',
+      'blockchainAccountId':'did:key:0x32234234234234'
+      })).toThrow()
+    expect(getChainIdForDidEthr({
+      'id': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51#controller',
+      'type': 'EcdsaSecp256k1RecoveryMethod2020',
+      'controller': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51',
+      'blockchainAccountId':'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51@eip155:1'
+    })).toEqual(1)
+    expect(getChainIdForDidEthr({
+      'id': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51#controller',
+      'type': 'EcdsaSecp256k1RecoveryMethod2020',
+      'controller': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51',
+      'blockchainAccountId':'eip155:1:did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51'
+    })).toEqual(1)
+    expect(getChainIdForDidEthr({
+      'id': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51#controller',
+      'type': 'EcdsaSecp256k1RecoveryMethod2020',
+      'controller': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51',
+      'blockchainAccountId':'did:ethr:rinkeby:0x1B54DaD834f2017ab66C1a1ffF74425889141e51@eip155:4'
+    })).toEqual(4)
+  })
+
+  it('should return blockchainAccountId for did:ethr', () => {
+    const verificationMethod = {
+      'id': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51#controller',
+      'type': 'EcdsaSecp256k1RecoveryMethod2020',
+      'controller': 'did:ethr:0x1B54DaD834f2017ab66C1a1ffF74425889141e51',
+      'blockchainAccountId': '0x1B54DaD834f2017ab66C1a1ffF74425889141e51@eip155:1'
+    }
+
+    expect(getEthereumAddress(verificationMethod)).toEqual("0x1B54DaD834f2017ab66C1a1ffF74425889141e51".toLowerCase())
+  })
+})

packages/utils/src/did-utils.ts

@@ -63,6 +63,27 @@ function compareBlockchainAccountId(localKey: IKey, verificationMethod: _Normali
   return computedAddr === vmEthAddr
 }
 
+export function getEthereumAddress(verificationMethod: _NormalizedVerificationMethod) {
+  let vmEthAddr = verificationMethod.ethereumAddress?.toLowerCase()
+  if (!vmEthAddr) {
+    if (verificationMethod.blockchainAccountId?.includes('@eip155')) {
+      vmEthAddr = verificationMethod.blockchainAccountId?.split('@eip155')[0].toLowerCase()
+    } else if (verificationMethod.blockchainAccountId?.startsWith('eip155')) {
+      vmEthAddr = verificationMethod.blockchainAccountId.split(':')[2]?.toLowerCase()
+    }
+  }
+  return vmEthAddr
+}
+
+export function getChainIdForDidEthr(verificationMethod: _NormalizedVerificationMethod): number {
+  if (verificationMethod.blockchainAccountId?.includes('@eip155')) {
+    return parseInt(verificationMethod.blockchainAccountId!.split(':').slice(-1)[0])
+  } else if (verificationMethod.blockchainAccountId?.startsWith('eip155')) {
+    return parseInt(verificationMethod.blockchainAccountId!.split(':')[1])
+  }
+  throw new Error('blockchainAccountId does not include eip155 designation')
+}
+
 export async function mapIdentifierKeysToDoc(
   identifier: IIdentifier,
   section: DIDDocumentSection = 'keyAgreement',