diff --git a/pyplayready/__init__.py b/pyplayready/__init__.py
index ec77f83..7351361 100644
--- a/pyplayready/__init__.py
+++ b/pyplayready/__init__.py
@@ -10,4 +10,4 @@ from .session import *
 from .xml_key import *
 from .xmrlicense import *
 
-__version__ = "0.4.2"
+__version__ = "0.4.3"
diff --git a/pyplayready/bcert.py b/pyplayready/bcert.py
index 2bb25ce..9bb6a1e 100644
--- a/pyplayready/bcert.py
+++ b/pyplayready/bcert.py
@@ -214,11 +214,6 @@ class Certificate(_BCertStructs):
             max_header: int = 15360,
             max_chain_depth: int = 2
     ) -> Certificate:
-        if not cert_id:
-            raise ValueError("Certificate ID is required")
-        if not client_id:
-            raise ValueError("Client ID is required")
-
         basic_info = Container(
             cert_id=cert_id,
             security_level=security_level,
@@ -250,9 +245,20 @@ class Certificate(_BCertStructs):
         feature = Container(
             feature_count=3,
             features=ListContainer([
-                4,  # SECURE_CLOCK
-                9,  # REVOCATION_LIST_FEATURE
-                13  # SUPPORTS_PR3_FEATURES
+                # 1,  # Transmitter
+                # 2,  # Receiver
+                # 3,  # SharedCertificate
+                4,  # SecureClock
+                5,  # AntiRollBackClock
+                # 6, # ReservedMetering
+                # 7, # ReservedLicSync
+                # 8, # ReservedSymOpt
+                9,  # CRLS (Revocation Lists)
+                # 10, # ServerBasicEdition
+                # 11, # ServerStandardEdition
+                # 12, # ServerPremiumEdition
+                13,  # PlayReady3Features
+                # 14, # DeprecatedSecureStop
             ])
         )
         feature_attribute = Container(
@@ -385,8 +391,10 @@ class Certificate(_BCertStructs):
         return self._BCERT
 
     def verify_signature(self):
-        sign_payload = self.dumps()[:-144]
-        signature_attribute = self.get_attribute(8).attribute
+        signature_object = self.get_attribute(8)
+        signature_attribute = signature_object.attribute
+
+        sign_payload = self.dumps()[:-signature_object.length]
 
         raw_signature_key = signature_attribute.signature_key
         signature_key = ECC.construct(
diff --git a/pyplayready/ecc_key.py b/pyplayready/ecc_key.py
index 8a39d0f..1fbf78b 100644
--- a/pyplayready/ecc_key.py
+++ b/pyplayready/ecc_key.py
@@ -56,15 +56,17 @@ class ECCKey:
         with Path(path).open(mode="rb") as f:
             return cls.loads(f.read())
 
-    def dumps(self):
+    def dumps(self, private_only=False):
+        if private_only:
+            return self.private_bytes()
         return self.private_bytes() + self.public_bytes()
 
-    def dump(self, path: Union[Path, str]) -> None:
+    def dump(self, path: Union[Path, str], private_only=False) -> None:
         if not isinstance(path, (Path, str)):
             raise ValueError(f"Expecting Path object or path string, got {path!r}")
         path = Path(path)
         path.parent.mkdir(parents=True, exist_ok=True)
-        path.write_bytes(self.dumps())
+        path.write_bytes(self.dumps(private_only))
 
     def get_point(self, curve: Curve) -> Point:
         return Point(self.key.pointQ.x, self.key.pointQ.y, curve)
diff --git a/pyplayready/key.py b/pyplayready/key.py
index 23cde0f..54ecca0 100644
--- a/pyplayready/key.py
+++ b/pyplayready/key.py
@@ -12,6 +12,7 @@ class Key:
         AES_128_ECB = 0x0003
         COCKTAIL = 0x0004
         AES_128_CBC = 0x0005
+        KEYEXCHANGE = 0x0006
         UNKNOWN = 0xffff
 
         @classmethod
@@ -24,7 +25,8 @@ class Key:
         CHAINED_LICENSE = 0x0002
         ECC_256 = 0x0003
         ECC_256_WITH_KZ = 0x0004
-        SCALABLE = 0x0005
+        TEE_TRANSIENT = 0x0005
+        ECC_256_VIA_SYMMETRIC = 0x0006
         UNKNOWN = 0xffff
 
         @classmethod
diff --git a/pyplayready/main.py b/pyplayready/main.py
index 0a691f0..570e441 100644
--- a/pyplayready/main.py
+++ b/pyplayready/main.py
@@ -279,7 +279,7 @@ def export_device(ctx: click.Context, prd_path: Path, out_dir: Optional[Path] =
 
     if device.group_key:
         group_key_path = out_path / "zgpriv.dat"
-        group_key_path.write_bytes(device.group_key.dumps())
+        group_key_path.write_bytes(device.group_key.dumps(private_only=True))
         log.info("Exported Group Key as zgpriv.dat")
     else:
         log.warning("Cannot export zgpriv.dat, as v2 devices do not save the group key")
diff --git a/pyproject.toml b/pyproject.toml
index 054b564..6251d18 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "pyplayready"
-version = "0.4.2"
+version = "0.4.3"
 description = "pyplayready CDM (Content Decryption Module) implementation in Python."
 license = "CC BY-NC-ND 4.0"
 authors = ["DevLARLEY, Erevoc", "DevataDev"]