diff --git a/fido2/ctap2/extensions.py b/fido2/ctap2/extensions.py
index 74583f9..c841e32 100644
--- a/fido2/ctap2/extensions.py
+++ b/fido2/ctap2/extensions.py
@@ -708,50 +708,59 @@ class SignExtension(Ctap2Extension):
 
     NAME = "sign"
 
-    def process_create_input(self, inputs):
+    def make_credential(self, ctap, options):
+        inputs = options.extensions or {}
         data = _SignInputs.from_dict(inputs.get("sign"))
-        if not data or not self.is_supported():
+        if not data or not self.is_supported(ctap):
             return
 
         if data.sign or not data.generate_key:
             raise ValueError("Invalid inputs")
 
-        gk = data.generate_key
-
-        selection = (
-            self._create_options.authenticator_selection
-            or AuthenticatorSelectionCriteria()
-        )
-        flags = (
-            0b101
-            if selection.user_verification == UserVerificationRequirement.REQUIRED
-            else 0b001
-        )
-        outputs = {3: gk.algorithms, 4: flags}
+        def prepare_inputs(_):
+            gk = data.generate_key
 
-        if gk.ph_data:
-            outputs[0] = gk.ph_data
+            selection = (
+                options.authenticator_selection or AuthenticatorSelectionCriteria()
+            )
+            flags = (
+                0b101
+                if selection.user_verification == UserVerificationRequirement.REQUIRED
+                else 0b001
+            )
+            outputs = {3: gk.algorithms, 4: flags}
 
-        return outputs
+            if gk.ph_data:
+                outputs[0] = gk.ph_data
 
-    def process_create_output(self, attestation_response, *args):
-        data = attestation_response.auth_data.extensions.get(self.NAME)
-        att_obj = AttestationResponse.from_dict(cbor.decode(data[7]))  # type: ignore
-        cred_data = att_obj.auth_data.credential_data
-        assert cred_data is not None  # nosec
-        pk = cred_data.public_key
+            return {self.NAME: outputs}
 
-        return {
-            "sign": _SignOutputs(
-                generated_key=_SignGeneratedKey(
-                    public_key=cbor.encode(pk),
-                    key_handle=cbor.encode(pk.get_ref()),
-                ),
-                signature=data.get(6),
+        def prepare_outputs(response, *args):
+            data = response.auth_data.extensions.get(self.NAME)
+            att_obj = AttestationResponse.from_dict(
+                cbor.decode(data[7])  # type: ignore
             )
-        }
+            cred_data = att_obj.auth_data.credential_data
+            assert cred_data is not None  # nosec
+            pk = cred_data.public_key
+
+            return {
+                self.NAME: _SignOutputs(
+                    generated_key=_SignGeneratedKey(
+                        public_key=cbor.encode(pk),
+                        key_handle=cbor.encode(pk.get_ref()),
+                    ),
+                    signature=data.get(6),
+                )
+            }
 
-    def process_get_input(self, inputs):
+        return ExtensionProcessor(
+            prepare_inputs=prepare_inputs,
+            prepare_outputs=prepare_outputs,
+        )
+
+    def get_assertion(self, ctap, options):
+        inputs = options.extensions or {}
         data = _SignInputs.from_dict(inputs.get("sign"))
         if not data or not self.is_supported():
             return
@@ -759,26 +768,31 @@ def process_get_input(self, inputs):
         if not data.sign or data.generate_key:
             raise ValueError("Invalid inputs")
 
-        sign = data.sign
-        by_creds = sign.key_handle_by_credential
-
-        # Make sure all keys are valid IDs from allow_credentials
-        allow_list = self._get_options.allow_credentials
-        if not allow_list:
-            raise ValueError("sign requires allowCredentials")
-        ids = {websafe_encode(c.id) for c in allow_list}
-        if ids.difference(by_creds):
-            raise ValueError("keyHandleByCredential is not valid")
-        if not self._selected:
-            return
-        kh = by_creds[websafe_encode(self._selected.id)]
-
-        return {
-            0: sign.ph_data,
-            5: [kh],
-        }
+        def prepare_inputs(selected):
+            sign = data.sign
+            by_creds = sign.key_handle_by_credential
+
+            # Make sure all keys are valid IDs from allow_credentials
+            allow_list = options.allow_credentials
+            if not allow_list or not selected:
+                raise ValueError("sign requires allowCredentials")
+            ids = {websafe_encode(c.id) for c in allow_list}
+            if ids.difference(by_creds):
+                raise ValueError("keyHandleByCredential is not valid")
+            kh = by_creds[websafe_encode(selected.id)]
+
+            return {
+                self.NAME: {
+                    0: sign.ph_data,
+                    5: [kh],
+                }
+            }
 
-    def process_get_output(self, assertion_response, *args):
-        data = assertion_response.auth_data.extensions.get(self.NAME)
+        def prepare_outputs(response, *args):
+            data = response.auth_data.extensions.get(self.NAME)
+            return {self.NAME: _SignOutputs(signature=data[6])}
 
-        return {"sign": _SignOutputs(signature=data[6])}
+        return ExtensionProcessor(
+            prepare_inputs=prepare_inputs,
+            prepare_outputs=prepare_outputs,
+        )