diff --git a/tests/test_certificate.py b/tests/test_certificate.py
index 3d5eac6..07447b2 100644
--- a/tests/test_certificate.py
+++ b/tests/test_certificate.py
@@ -111,6 +111,30 @@ def test_verifiable_credential():
     assert verified
 
 
+def test_verifiable_credential_fail():
+    key = generate_keys()
+    did = generate_did(key)
+    signing_key = get_signing_key(key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+
+    cred = json.dumps(credential)
+
+    vc = sign(cred, signing_key, did)
+    vc["id"] = "bar"
+    verified = verify_vc(json.dumps(vc))
+    assert not verified
+
+
 def test_verifiable_presentation():
     key = generate_keys()
     did = generate_did(key)
@@ -139,3 +163,63 @@ def test_verifiable_presentation():
     verified = verify_vp(json.dumps(vp))
     assert verified
 
+
+def test_verifiable_presentation_fail1():
+    key = generate_keys()
+    did = generate_did(key)
+    signing_key = get_signing_key(key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+
+    cred = json.dumps(credential)
+
+    vc = sign(cred, signing_key, did)
+    vc_json = json.dumps(vc)
+
+    holder_key = generate_keys()
+    holder_did = generate_did(holder_key)
+    holder_signing_key = get_signing_key(holder_key)
+    vp = sign_vp(holder_signing_key, holder_did, vc_json)
+    vp["verifiableCredential"][0]["id"] = "bar"
+    verified = verify_vp(json.dumps(vp))
+    assert not verified
+
+
+def test_verifiable_presentation_fail2():
+    key = generate_keys()
+    did = generate_did(key)
+    signing_key = get_signing_key(key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+
+    cred = json.dumps(credential)
+
+    vc = sign(cred, signing_key, did)
+    vc_json = json.dumps(vc)
+
+    holder_key = generate_keys()
+    holder_did = generate_did(holder_key)
+    holder_signing_key = get_signing_key(holder_key)
+    vp = sign_vp(holder_signing_key, holder_did, vc_json)
+    vp["id"] = "http://example.org/presentations/3732"
+    verified = verify_vp(json.dumps(vp))
+    assert not verified
+
diff --git a/tests/test_interoperability.py b/tests/test_interoperability.py
index 632cec8..91a6923 100644
--- a/tests/test_interoperability.py
+++ b/tests/test_interoperability.py
@@ -1,12 +1,84 @@
 import json
+import asyncio
 import didkit
-import multicodec
-import multiformats
-import nacl.encoding
+# import multicodec
+# import multiformats
+# import nacl.encoding
+from ast import literal_eval
 
-from did import generate_keys, generate_did
+from sign_vc import sign
+from sign_vp import sign_vp
+from verify import verify_vc
+from verify_vp import verify_vp
+from utils import now
+from did import generate_keys, generate_did, get_signing_key
 
 
+def verify_credential(vc):
+    async def inner():
+        try:
+            return await didkit.verify_credential(vc, '{"proofFormat": "ldp"}')
+        except Exception:
+            return False
+
+    return asyncio.run(inner())
+
+
+def render_and_sign_credential(unsigned_vc, jwk_issuer):
+    async def inner():
+        signed_vc = await didkit.issue_credential(
+            json.dumps(unsigned_vc),
+            '{"proofFormat": "ldp"}',
+            jwk_issuer
+        )
+        return signed_vc
+
+    return asyncio.run(inner())
+
+
+def verify_presentation(vp: str):
+    async def inner():
+        str_res = await didkit.verify_presentation(vp, '{"proofFormat": "ldp"}')
+        res = literal_eval(str_res)
+        ok = res["warnings"] == [] and res["errors"] == []
+        return ok, str_res
+
+    valid, reason = asyncio.run(inner())
+    if not valid:
+        return False
+
+    vp = json.loads(vp)
+    for credential in vp["verifiableCredential"]:
+        valid = verify_credential(json.dumps(credential))
+        if not valid:
+            return False
+
+    return True
+
+
+def issue_verifiable_presentation(vc_list, jwk_holder, holder_did, presentation_id):
+    async def inner(unsigned_vp):
+        signed_vp = await didkit.issue_presentation(
+            unsigned_vp,
+            '{"proofFormat": "ldp"}',
+            jwk_holder
+        )
+        return signed_vp
+
+    unsigned_vp = json.dumps({
+        "@context": [
+            "https://www.w3.org/2018/credentials/v1"
+        ],
+        "id": presentation_id,
+        "type": [
+            "VerifiablePresentation"
+        ],
+        "holder": holder_did,
+        "verifiableCredential": vc_list
+    })
+
+    return asyncio.run(inner(unsigned_vp))
+
 def test_key_from_didkit():
     key = didkit.generate_ed25519_key()
     did_didkit = didkit.key_to_did("key", key)
@@ -21,3 +93,197 @@ def test_key_from_pyvckit():
     assert did_didkit == did_pyvckit
 
 
+def test_pyvckit_credential_validated_from_didkit():
+    key = generate_keys()
+    did = generate_did(key)
+    signing_key = get_signing_key(key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+
+    cred = json.dumps(credential)
+
+    vc = sign(cred, signing_key, did)
+    result = verify_credential(json.dumps(vc))
+    assert result == '{"checks":["proof"],"warnings":[],"errors":[]}'
+
+
+def test_didkit_credential_validated_from_pyvckit():
+    key = didkit.generate_ed25519_key()
+    did = didkit.key_to_did("key", key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+
+    cred_signed = render_and_sign_credential(credential, key)
+
+    result = verify_vc(cred_signed)
+    assert result
+
+
+def test_pyvckit_presentation_validated_from_didkit():
+    key = generate_keys()
+    did = generate_did(key)
+    signing_key = get_signing_key(key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+
+    cred = json.dumps(credential)
+
+    vc = sign(cred, signing_key, did)
+    vc_json = json.dumps(vc)
+
+    holder_key = generate_keys()
+    holder_did = generate_did(holder_key)
+    holder_signing_key = get_signing_key(holder_key)
+    vp = sign_vp(holder_signing_key, holder_did, vc_json)
+
+    result = verify_presentation(json.dumps(vp))
+    assert result
+
+
+def test_fail_pyvckit_presentation_validated_from_didkit():
+    key = generate_keys()
+    did = generate_did(key)
+    signing_key = get_signing_key(key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+
+    cred = json.dumps(credential)
+
+    vc = sign(cred, signing_key, did)
+    vc_json = json.dumps(vc)
+
+    holder_key = generate_keys()
+    holder_did = generate_did(holder_key)
+    holder_signing_key = get_signing_key(holder_key)
+    vp = sign_vp(holder_signing_key, holder_did, vc_json)
+    vp["verifiableCredential"][0]["id"] = "bar"
+    vp_fail = json.dumps(vp)
+
+    result = verify_vp(vp_fail)
+    result2 = verify_presentation(vp_fail)
+
+    assert result == result2
+    assert not result
+
+
+def test_didkit_presentation_validated_from_pyvckit():
+    key = didkit.generate_ed25519_key()
+    did = didkit.key_to_did("key", key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+    cred_signed = render_and_sign_credential(credential, key)
+
+    holder_key = didkit.generate_ed25519_key()
+    holder_did = didkit.key_to_did("key", holder_key)
+
+    vc_list = [json.loads(cred_signed)]
+    vp_signed = issue_verifiable_presentation(vc_list, holder_key, holder_did, "1")
+
+    result = verify_vp(vp_signed)
+    assert result
+
+
+def test_fail_didkit_presentation_validated_from_pyvckit():
+    key = didkit.generate_ed25519_key()
+    did = didkit.key_to_did("key", key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+    cred_signed = render_and_sign_credential(credential, key)
+
+    holder_key = didkit.generate_ed25519_key()
+    holder_did = didkit.key_to_did("key", holder_key)
+
+    vc_list = [json.loads(cred_signed)]
+    vp_signed = issue_verifiable_presentation(vc_list, holder_key, holder_did, "1")
+    vp = json.loads(vp_signed)
+    vp["verifiableCredential"][0]["id"] = "bar"
+    vp_fail = json.dumps(vp)
+
+    result = verify_vp(vp_fail)
+    assert not result
+
+
+def test_fail2_didkit_presentation_validated_from_pyvckit():
+    key = didkit.generate_ed25519_key()
+    did = didkit.key_to_did("key", key)
+
+    credential = {
+        "@context": "https://www.w3.org/2018/credentials/v1",
+        "id": "http://example.org/credentials/3731",
+        "type": ["VerifiableCredential"],
+        "credentialSubject": {
+            "id": "did:key:z6MkgGXSJoacuuNdwU1rGfPpFH72GACnzykKTxzCCTZs6Z2M",
+        },
+        "issuer": did,
+        "issuanceDate": now()
+    }
+    cred_signed = render_and_sign_credential(credential, key)
+
+    holder_key = didkit.generate_ed25519_key()
+    holder_did = didkit.key_to_did("key", holder_key)
+
+    vc_list = [json.loads(cred_signed)]
+    vp_signed = issue_verifiable_presentation(vc_list, holder_key, holder_did, "1")
+    vp = json.loads(vp_signed)
+    vp['proof']['created'] = now()
+    vp_fail = json.dumps(vp)
+
+    result = verify_vp(vp_fail)
+    result2 = verify_presentation(vp_fail)
+    assert result == result2
+    assert not result
+