Soporte para revocación

Falta de alguna manera especificar cuando se crean los did:web, que son prerequisito para revocar credenciales

idhub/views.py

@@ -1,6 +1,9 @@
+import base64
 import json
 import uuid
+import zlib
 
+import pyroaring
 from django.conf import settings
 from django.core.cache import cache
 from django.urls import reverse_lazy
@@ -82,16 +85,21 @@ def serve_did(request, did_id):
     did = get_object_or_404(DID, did=id_did)
     # Deserialize the base DID from JSON storage
     document = json.loads(did.didweb_document)
+    # Has this DID issued any Verifiable Credentials? If so, we need to add a Revocation List "service"
+    #  entry to the DID document.
     revoked_credentials = did.verificablecredential_set.filter(status=VerificableCredential.Status.REVOKED)
     revoked_credential_indexes = []
     for credential in revoked_credentials:
         revoked_credential_indexes.append(credential.revocationBitmapIndex)
-    encoded_revocation_bitmap = None  # TODO
+    # TODO: Conditionally add "service" to DID document only if the DID has issued any VC
+    revocation_bitmap = pyroaring.BitMap(revoked_credential_indexes)
+    encoded_revocation_bitmap = base64.b64encode(zlib.compress(revocation_bitmap.serialize()))
     revocation_service = [{
         "id": f"{id_did}#revocation",
         "type": "RevocationBitmap2022",
         "serviceEndpoint": f"data:application/octet-stream;base64,{encoded_revocation_bitmap}"
     }]
+    document["service"] = revocation_service
     # Serialize the DID + Revocation list in preparation for sending
     document = json.dumps(document)
     retval = HttpResponse(document)

requirements.txt

@@ -28,3 +28,4 @@ fontTools==4.47.0
 weasyprint==60.2
 ujson==5.9.0
 ./didkit-0.3.2-cp311-cp311-manylinux_2_34_x86_64.whl
+pyroaring==0.4.5

utils/idhub_ssikit/__init__.py

@@ -1,11 +1,15 @@
 import asyncio
+import base64
 import datetime
+import zlib
+
 import didkit
 import json
 import urllib
 import jinja2
 from django.template.backends.django import Template
 from django.template.loader import get_template
+from pyroaring import BitMap
 
 from trustchain_idhub import settings
 
@@ -18,8 +22,11 @@ def keydid_from_controller_key(key):
     return didkit.key_to_did("key", key)
 
 
-async def resolve_keydid(keydid):
+def resolve_did(keydid):
-    return await didkit.resolve_did(keydid, "{}")
+    async def inner():
+        return await didkit.resolve_did(keydid, "{}")
+
+    return asyncio.run(inner())
 
 
 def webdid_from_controller_key(key):
@@ -29,7 +36,7 @@ def webdid_from_controller_key(key):
     """
     keydid = keydid_from_controller_key(key)  # "did:key:<...>"
     pubkeyid = keydid.rsplit(":")[-1]  # <...>
-    document = json.loads(asyncio.run(resolve_keydid(keydid)))  # Documento DID en terminos "key"
+    document = json.loads(resolve_did(keydid))  # Documento DID en terminos "key"
     domain = urllib.parse.urlencode({"domain": settings.DOMAIN})[7:]
     webdid_url = f"did:web:{domain}:did-registry:{pubkeyid}"  # nueva URL: "did:web:idhub.pangea.org:<...>"
     webdid_url_owner = webdid_url + "#owner"
@@ -105,6 +112,28 @@ def verify_credential(vc):
     if not valid:
         return valid, reason
     # Credential passes basic signature verification. Now check it against its schema.
+    # TODO: check agasint schema
+    pass
+    # Credential verifies against its schema. Now check revocation status.
+    vc = json.loads(vc)
+    revocation_index = int(vc["credentialStatus"]["revocationBitmapIndex"])  # NOTE: THIS FIELD SHOULD BE SERIALIZED AS AN INTEGER, BUT IOTA DOCUMENTAITON SERIALIZES IT AS A STRING. DEFENSIVE CAST ADDED JUST IN CASE.
+    vc_issuer = vc["issuer"]["id"]  # This is a DID
+    issuer_did_document = json.loads(resolve_did(vc_issuer))  # TODO: implement a caching layer so we don't have to fetch the DID (and thus the revocation list) every time a VC is validated.
+    issuer_revocation_list = issuer_did_document["service"][0]
+    assert issuer_revocation_list["type"] == "RevocationBitmap2022"
+    revocation_bitmap = BitMap.deserialize(
+        zlib.decompress(
+            base64.b64decode(
+                issuer_revocation_list["serviceEndpoint"].rsplit(",")[1]
+            )
+        )
+    )
+    if revocation_index in revocation_bitmap:
+        return False, "Credential has been revoked by the issuer"
+    # Fallthrough means all is good.
+    return True, ""
+
+
 
 
 def issue_verifiable_presentation(vp_template: Template, vc_list: list[str], jwk_holder: str, holder_did: str) -> str: