feat: add external suite provider

To make signing mechanisms for JSON-LD pluggable.

Signed-off-by: Daniel Bluhm <[email protected]>

aries_cloudagent/vc/vc_ld/external_suite.py

@@ -0,0 +1,44 @@
+"""Plugin hook for providing an external signature suite implementation.
+
+This enables greater control over where JSON-LD credentials are signed without
+requiring knowledge of the complexities of the JSON-LD/VC-LDP subsystem.
+"""
+
+from abc import ABC, abstractmethod
+from typing import Optional
+
+from ...core.error import BaseError
+from ...core.profile import Profile
+from ...wallet.did_info import DIDInfo
+from ..ld_proofs.suites.linked_data_proof import LinkedDataProof
+
+
+class ExternalSuiteError(BaseError):
+    """Raised when an error occurs in an external signature suite provider."""
+
+
+class ExternalSuiteNotFoundError(ExternalSuiteError):
+    """Raised when an external signature suite provider is not found.
+
+    This should be raised to prevent falling back to built in suites, if desired.
+    """
+
+
+class ExternalSuiteProvider(ABC):
+    """Plugin hook for providing an external signature suite implementation."""
+
+    @abstractmethod
+    def get_suite(
+        self,
+        profile: Profile,
+        proof_type: str,
+        proof: dict,
+        verification_method: str,
+        did_info: DIDInfo,
+    ) -> Optional[LinkedDataProof]:
+        """Get a signature suite for the given proof type and verification method.
+
+        Implementing classes should raise ExternalSuiteNotFoundError if preventing
+        fallback to built-in suites is desired. Otherwise, return None to indicate
+        that the implementing class does not support the given proof type.
+        """

aries_cloudagent/vc/vc_ld/manager.py

@@ -1,17 +1,18 @@
 """Manager for performing Linked Data Proof signatures over JSON-LD formatted W3C VCs."""
 
 from typing import Dict, List, Optional, Type, Union, cast
+
 from pyld import jsonld
 from pyld.jsonld import JsonLdProcessor
 
 from ...core.profile import Profile
+from ...storage.vc_holder.base import VCHolder
+from ...storage.vc_holder.vc_record import VCRecord
 from ...wallet.base import BaseWallet
 from ...wallet.default_verification_key_strategy import BaseVerificationKeyStrategy
 from ...wallet.did_info import DIDInfo
 from ...wallet.error import WalletNotFoundError
 from ...wallet.key_type import BLS12381G2, ED25519, KeyType
-from ...storage.vc_holder.base import VCHolder
-from ...storage.vc_holder.vc_record import VCRecord
 from ..ld_proofs.constants import (
     SECURITY_CONTEXT_BBS_URL,
     SECURITY_CONTEXT_ED25519_2020_URL,
@@ -29,11 +30,12 @@
 from ..ld_proofs.validation_result import DocumentVerificationResult
 from ..vc_ld.models.presentation import VerifiablePresentation
 from ..vc_ld.validation_result import PresentationVerificationResult
+from .external_suite import ExternalSuiteNotFoundError, ExternalSuiteProvider
 from .issue import issue as ldp_issue
-from .prove import sign_presentation
 from .models.credential import VerifiableCredential
 from .models.linked_data_proof import LDProof
 from .models.options import LDProofVCOptions
+from .prove import sign_presentation
 from .verify import verify_credential, verify_presentation
 
 SignatureTypes = Union[
@@ -182,6 +184,20 @@ async def _get_suite(
         did_info: Optional[DIDInfo] = None,
     ):
         """Get signature suite for issuance of verification."""
+        # Try to get suite from external provider first
+        try:
+            if (provider := self.profile.inject_or(ExternalSuiteProvider)) and (
+                suite := provider.get_suite(
+                    self.profile, proof_type, proof, verification_method, did_info
+                )
+            ):
+                return suite
+        except ExternalSuiteNotFoundError as error:
+            raise VcLdpManagerError(
+                f"Unable to get signature suite for proof type {proof_type} "
+                "using external provider."
+            ) from error
+
         # Get signature class based on proof type
         SignatureClass = PROOF_TYPE_SIGNATURE_SUITE_MAPPING[proof_type]