diff --git a/pyvckit/sign_vc.py b/pyvckit/sign_vc.py
index 2516f30..2420e88 100644
--- a/pyvckit/sign_vc.py
+++ b/pyvckit/sign_vc.py
@@ -10,7 +10,7 @@ from pyvckit.sign import sign_proof
 
 def sign(credential, key, issuer_did):
     document = json.loads(credential)
-    _did = issuer_did + "#" + issuer_did.split("did:key:")[1]
+    _did = issuer_did + "#" + issuer_did.split(":")[-1]
     proof = json.loads(proof_tmpl)
     proof['verificationMethod'] = _did
     proof['created'] = now()
diff --git a/pyvckit/sign_vp.py b/pyvckit/sign_vp.py
index d26e5fa..eed0661 100644
--- a/pyvckit/sign_vp.py
+++ b/pyvckit/sign_vp.py
@@ -12,7 +12,7 @@ def sign_vp(signing_key, holder_did, vc):
     presentation["verifiableCredential"].append(json.loads(vc))
     presentation["holder"] = holder_did
 
-    _did = holder_did + "#" + holder_did.split("did:key:")[1]
+    _did = holder_did + "#" + holder_did.split(":")[-1]
     proof = json.loads(proof_tmpl)
     proof['verificationMethod'] = _did
     proof['created'] = now()