refactor: Extract verification method ID generation to a separate class

aries_cloudagent/config/default_context.py

@@ -17,6 +17,7 @@
 from ..transport.wire_format import BaseWireFormat
 from ..utils.dependencies import is_indy_sdk_module_installed
 from ..utils.stats import Collector
+from ..wallet.default_verification_key_strategy import DefaultVerificationKeyStrategy
 from ..wallet.did_method import DIDMethods
 from ..wallet.key_type import KeyTypes
 from .base_context import ContextBuilder
@@ -53,6 +54,9 @@ async def build_context(self) -> InjectionContext:
         context.injector.bind_instance(DIDResolver, DIDResolver([]))
         context.injector.bind_instance(DIDMethods, DIDMethods())
         context.injector.bind_instance(KeyTypes, KeyTypes())
+        context.injector.bind_instance(
+            DefaultVerificationKeyStrategy, DefaultVerificationKeyStrategy()
+        )
 
         await self.bind_providers(context)
         await self.load_plugins(context)

aries_cloudagent/protocols/issue_credential/v2_0/formats/ld_proof/handler.py

@@ -12,7 +12,6 @@
 from pyld import jsonld
 from pyld.jsonld import JsonLdProcessor
 
-from ......did.did_key import DIDKey
 from ......messaging.decorators.attach_decorator import AttachDecorator
 from ......storage.vc_holder.base import VCHolder
 from ......storage.vc_holder.vc_record import VCRecord
@@ -35,6 +34,9 @@
 )
 from ......vc.ld_proofs.constants import SECURITY_CONTEXT_BBS_URL
 from ......wallet.base import BaseWallet, DIDInfo
+from ......wallet.default_verification_key_strategy import (
+    DefaultVerificationKeyStrategy,
+)
 from ......wallet.error import WalletNotFoundError
 from ......wallet.key_type import BLS12381G2, ED25519
 
@@ -270,10 +272,17 @@ async def _get_suite_for_detail(
         )
 
         did_info = await self._did_info_for_did(issuer_id)
-        verification_method = verification_method or self._get_verification_method(
-            issuer_id
+        verkey_id_strategy = self.profile.context.inject(DefaultVerificationKeyStrategy)
+        verification_method = (
+            verification_method
+            or verkey_id_strategy.get_verification_method_id_for_did(issuer_id)
         )
 
+        if verification_method is None:
+            raise V20CredFormatError(
+                f"Unable to get retrieve verification method for did {issuer_id}"
+            )
+
         suite = await self._get_suite(
             proof_type=proof_type,
             verification_method=verification_method,
@@ -309,19 +318,6 @@ async def _get_suite(
             ),
         )
 
-    def _get_verification_method(self, did: str):
-        """Get the verification method for a did."""
-
-        if did.startswith("did:key:"):
-            return DIDKey.from_did(did).key_id
-        elif did.startswith("did:sov:"):
-            # key-1 is what the resolver uses for key id
-            return did + "#key-1"
-        else:
-            raise V20CredFormatError(
-                f"Unable to get retrieve verification method for did {did}"
-            )
-
     def _get_proof_purpose(
         self, *, proof_purpose: str = None, challenge: str = None, domain: str = None
     ) -> ProofPurpose:

aries_cloudagent/protocols/issue_credential/v2_0/formats/ld_proof/tests/test_handler.py

@@ -26,6 +26,9 @@
 )
 from .......vc.ld_proofs.constants import SECURITY_CONTEXT_BBS_URL
 from .......vc.tests.document_loader import custom_document_loader
+from .......wallet.default_verification_key_strategy import (
+    DefaultVerificationKeyStrategy,
+)
 from .......wallet.key_type import BLS12381G2, ED25519
 from .......wallet.error import WalletNotFoundError
 from .......wallet.did_method import SOV
@@ -124,6 +127,11 @@ async def setUp(self):
         # Set custom document loader
         self.context.injector.bind_instance(DocumentLoader, custom_document_loader)
 
+        # Set default verkey ID strategy
+        self.context.injector.bind_instance(
+            DefaultVerificationKeyStrategy, DefaultVerificationKeyStrategy()
+        )
+
         self.handler = LDProofCredFormatHandler(self.profile)
 
         self.cred_proposal = V20CredProposal(
@@ -318,24 +326,6 @@ async def test_get_suite(self):
         assert suite.key_pair.key_type == ED25519
         assert suite.key_pair.public_key_base58 == did_info.verkey
 
-    async def test_get_verification_method(self):
-        assert (
-            self.handler._get_verification_method(TEST_DID_KEY)
-            == DIDKey.from_did(TEST_DID_KEY).key_id
-        )
-
-        assert (
-            self.handler._get_verification_method(TEST_DID_SOV)
-            == TEST_DID_SOV + "#key-1"
-        )
-
-        with self.assertRaises(V20CredFormatError) as context:
-            self.handler._get_verification_method("did:random:not-supported")
-
-        assert "Unable to get retrieve verification method for did" in str(
-            context.exception
-        )
-
     async def test_get_proof_purpose(self):
         purpose = self.handler._get_proof_purpose()
         assert type(purpose) == CredentialIssuancePurpose

aries_cloudagent/protocols/present_proof/dif/pres_exch_handler.py

@@ -24,7 +24,6 @@
 
 from ....core.error import BaseError
 from ....core.profile import Profile
-from ....did.did_key import DIDKey
 from ....storage.vc_holder.vc_record import VCRecord
 from ....vc.ld_proofs import (
     Ed25519Signature2018,
@@ -39,6 +38,7 @@
 )
 from ....vc.vc_ld.prove import sign_presentation, create_presentation, derive_credential
 from ....wallet.base import BaseWallet, DIDInfo
+from ....wallet.default_verification_key_strategy import DefaultVerificationKeyStrategy
 from ....wallet.error import WalletError, WalletNotFoundError
 from ....wallet.key_type import BLS12381G2, ED25519
 
@@ -117,7 +117,15 @@ async def _get_issue_suite(
     ):
         """Get signature suite for signing presentation."""
         did_info = await self._did_info_for_did(issuer_id)
-        verification_method = self._get_verification_method(issuer_id)
+        verkey_id_strategy = self.profile.context.inject(DefaultVerificationKeyStrategy)
+        verification_method = verkey_id_strategy.get_verification_method_id_for_did(
+            issuer_id
+        )
+
+        if verification_method is None:
+            raise DIFPresExchError(
+                f"Unable to get retrieve verification method for did {issuer_id}"
+            )
 
         # Get signature class based on proof type
         SignatureClass = self.PROOF_TYPE_SIGNATURE_SUITE_MAPPING[self.proof_type]
@@ -151,18 +159,6 @@ async def _get_derive_suite(
             ),
         )
 
-    def _get_verification_method(self, did: str):
-        """Get the verification method for a did."""
-        if did.startswith("did:key:"):
-            return DIDKey.from_did(did).key_id
-        elif did.startswith("did:sov:"):
-            # key-1 is what uniresolver uses for key id
-            return did + "#key-1"
-        else:
-            raise DIFPresExchError(
-                f"Unable to get retrieve verification method for did {did}"
-            )
-
     async def _did_info_for_did(self, did: str) -> DIDInfo:
         """Get the did info for specified did.
 

aries_cloudagent/protocols/present_proof/dif/tests/test_pres_exch_handler.py

@@ -15,6 +15,7 @@
 from .....storage.vc_holder.vc_record import VCRecord
 from .....wallet.base import BaseWallet, DIDInfo
 from .....wallet.crypto import KeyType
+from .....wallet.default_verification_key_strategy import DefaultVerificationKeyStrategy
 from .....wallet.did_method import SOV, KEY, DIDMethods
 from .....wallet.error import WalletNotFoundError
 from .....vc.ld_proofs import (
@@ -73,6 +74,9 @@ def profile():
     context = profile.context
     context.injector.bind_instance(DIDResolver, DIDResolver([]))
     context.injector.bind_instance(DocumentLoader, custom_document_loader)
+    context.injector.bind_instance(
+        DefaultVerificationKeyStrategy, DefaultVerificationKeyStrategy()
+    )
     context.settings["debug.auto_respond_presentation_request"] = True
     return profile
 
@@ -1867,19 +1871,6 @@ def test_cred_schema_match_b(self, profile, setup_tuple):
             test_cred, "https://example.org/examples/degree.json"
         )
 
-    def test_verification_method(self, profile):
-        dif_pres_exch_handler = DIFPresExchHandler(profile)
-        assert (
-            dif_pres_exch_handler._get_verification_method(
-                "did:key:z6Mkgg342Ycpuk263R9d8Aq6MUaxPn1DDeHyGo38EefXmgDL"
-            )
-            == DIDKey.from_did(
-                "did:key:z6Mkgg342Ycpuk263R9d8Aq6MUaxPn1DDeHyGo38EefXmgDL"
-            ).key_id
-        )
-        with pytest.raises(DIFPresExchError):
-            dif_pres_exch_handler._get_verification_method("did:test:test")
-
     @pytest.mark.asyncio
     @pytest.mark.ursa_bbs_signatures
     async def test_sign_pres_no_cred_subject_id(self, profile, setup_tuple):

aries_cloudagent/wallet/default_verification_key_strategy.py

@@ -0,0 +1,43 @@
+"""Utilities for specifying which verification method is in use for a given DID."""
+from abc import ABC, abstractmethod
+from typing import Optional
+
+from aries_cloudagent.did.did_key import DIDKey
+
+
+class DefaultVerificationKeyStrategyBase(ABC):
+    """Base class for defining which verification method is in use."""
+
+    @abstractmethod
+    def get_verification_method_id_for_did(self, did) -> Optional[str]:
+        """Given a DID, returns the verification key ID in use.
+
+        Returns None if no strategy is specified for this DID.
+
+        :params str did: the did
+        :returns Optional[str]: the current verkey ID
+        """
+        pass
+
+
+class DefaultVerificationKeyStrategy(DefaultVerificationKeyStrategyBase):
+    """A basic implementation for verkey strategy.
+
+    Supports did:key: and did:sov only.
+    """
+
+    def get_verification_method_id_for_did(self, did) -> Optional[str]:
+        """Given a did:key or did:sov, returns the verification key ID in use.
+
+        Returns None if no strategy is specified for this DID.
+
+        :params str did: the did
+        :returns Optional[str]: the current verkey ID
+        """
+        if did.startswith("did:key:"):
+            return DIDKey.from_did(did).key_id
+        elif did.startswith("did:sov:"):
+            # key-1 is what uniresolver uses for key id
+            return did + "#key-1"
+
+        return None

aries_cloudagent/wallet/tests/test_default_verification_key_strategy.py

@@ -0,0 +1,30 @@
+from unittest import TestCase
+
+from aries_cloudagent.did.did_key import DIDKey
+
+from aries_cloudagent.wallet.default_verification_key_strategy import (
+    DefaultVerificationKeyStrategy,
+)
+
+TEST_DID_SOV = "did:sov:LjgpST2rjsoxYegQDRm7EL"
+TEST_DID_KEY = "did:key:z6Mkgg342Ycpuk263R9d8Aq6MUaxPn1DDeHyGo38EefXmgDL"
+
+
+class TestDefaultVerificationKeyStrategy(TestCase):
+    def test_with_did_sov(self):
+        strategy = DefaultVerificationKeyStrategy()
+        assert (
+            strategy.get_verification_method_id_for_did(TEST_DID_SOV)
+            == TEST_DID_SOV + "#key-1"
+        )
+
+    def test_with_did_key(self):
+        strategy = DefaultVerificationKeyStrategy()
+        assert (
+            strategy.get_verification_method_id_for_did(TEST_DID_KEY)
+            == DIDKey.from_did(TEST_DID_KEY).key_id
+        )
+
+    def test_unsupported_did_method(self):
+        strategy = DefaultVerificationKeyStrategy()
+        assert strategy.get_verification_method_id_for_did("did:test:test") is None