force PIN changes

src/ctap/config_command.rs

@@ -248,6 +248,62 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_process_set_min_pin_length_force_pin_change_implicit() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+
+        persistent_store.set_pin(&[0x88; 16], 4).unwrap();
+        // Increase min PIN, force PIN change.
+        let min_pin_length = 6;
+        let mut config_params = create_min_pin_config_params(min_pin_length, None);
+        let pin_uv_auth_param = Some(vec![
+            0x81, 0x37, 0x37, 0xF3, 0xD8, 0x69, 0xBD, 0x74, 0xFE, 0x88, 0x30, 0x8C, 0xC4, 0x2E,
+            0xA8, 0xC8,
+        ]);
+        config_params.pin_uv_auth_param = pin_uv_auth_param;
+        let config_response =
+            process_config(&mut persistent_store, &mut pin_protocol_v1, config_params);
+        assert_eq!(config_response, Ok(ResponseData::AuthenticatorConfig));
+        assert_eq!(persistent_store.min_pin_length(), Ok(min_pin_length));
+        assert_eq!(persistent_store.has_force_pin_change(), Ok(true));
+    }
+
+    #[test]
+    fn test_process_set_min_pin_length_force_pin_change_explicit() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        let key_agreement_key = crypto::ecdh::SecKey::gensk(&mut rng);
+        let pin_uv_auth_token = [0x55; 32];
+        let mut pin_protocol_v1 = PinProtocolV1::new_test(key_agreement_key, pin_uv_auth_token);
+
+        persistent_store.set_pin(&[0x88; 16], 4).unwrap();
+        let pin_uv_auth_param = Some(vec![
+            0xE3, 0x74, 0xF4, 0x27, 0xBE, 0x7D, 0x40, 0xB5, 0x71, 0xB6, 0xB4, 0x1A, 0xD2, 0xC1,
+            0x53, 0xD7,
+        ]);
+        let set_min_pin_length_params = SetMinPinLengthParams {
+            new_min_pin_length: Some(persistent_store.min_pin_length().unwrap()),
+            min_pin_length_rp_ids: None,
+            force_change_pin: Some(true),
+        };
+        let config_params = AuthenticatorConfigParameters {
+            sub_command: ConfigSubCommand::SetMinPinLength,
+            sub_command_params: Some(ConfigSubCommandParams::SetMinPinLength(
+                set_min_pin_length_params,
+            )),
+            pin_uv_auth_param,
+            pin_uv_auth_protocol: Some(1),
+        };
+        let config_response =
+            process_config(&mut persistent_store, &mut pin_protocol_v1, config_params);
+        assert_eq!(config_response, Ok(ResponseData::AuthenticatorConfig));
+        assert_eq!(persistent_store.has_force_pin_change(), Ok(true));
+    }
+
     #[test]
     fn test_process_config_vendor_prototype() {
         let mut rng = ThreadRng256 {};

src/ctap/mod.rs

@@ -1006,6 +1006,10 @@ where
         );
         options_map.insert(String::from("credMgmt"), true);
         options_map.insert(String::from("setMinPINLength"), true);
+        options_map.insert(
+            String::from("forcePINChange"),
+            self.persistent_store.has_force_pin_change()?,
+        );
         Ok(ResponseData::AuthenticatorGetInfo(
             AuthenticatorGetInfoResponse {
                 versions: vec![
@@ -1256,13 +1260,15 @@ mod test {
         expected_response.extend(&ctap_state.persistent_store.aaguid().unwrap());
         expected_response.extend(
             [
-                0x04, 0xA5, 0x62, 0x72, 0x6B, 0xF5, 0x62, 0x75, 0x70, 0xF5, 0x68, 0x63, 0x72, 0x65,
+                0x04, 0xA6, 0x62, 0x72, 0x6B, 0xF5, 0x62, 0x75, 0x70, 0xF5, 0x68, 0x63, 0x72, 0x65,
                 0x64, 0x4D, 0x67, 0x6D, 0x74, 0xF5, 0x69, 0x63, 0x6C, 0x69, 0x65, 0x6E, 0x74, 0x50,
-                0x69, 0x6E, 0xF4, 0x6F, 0x73, 0x65, 0x74, 0x4D, 0x69, 0x6E, 0x50, 0x49, 0x4E, 0x4C,
+                0x69, 0x6E, 0xF4, 0x6E, 0x66, 0x6F, 0x72, 0x63, 0x65, 0x50, 0x49, 0x4E, 0x43, 0x68,
-                0x65, 0x6E, 0x67, 0x74, 0x68, 0xF5, 0x05, 0x19, 0x04, 0x00, 0x06, 0x81, 0x01, 0x08,
+                0x61, 0x6E, 0x67, 0x65, 0xF4, 0x6F, 0x73, 0x65, 0x74, 0x4D, 0x69, 0x6E, 0x50, 0x49,
-                0x18, 0x70, 0x09, 0x81, 0x63, 0x75, 0x73, 0x62, 0x0A, 0x81, 0xA2, 0x63, 0x61, 0x6C,
+                0x4E, 0x4C, 0x65, 0x6E, 0x67, 0x74, 0x68, 0xF5, 0x05, 0x19, 0x04, 0x00, 0x06, 0x81,
-                0x67, 0x26, 0x64, 0x74, 0x79, 0x70, 0x65, 0x6A, 0x70, 0x75, 0x62, 0x6C, 0x69, 0x63,
+                0x01, 0x08, 0x18, 0x70, 0x09, 0x81, 0x63, 0x75, 0x73, 0x62, 0x0A, 0x81, 0xA2, 0x63,
-                0x2D, 0x6B, 0x65, 0x79, 0x0D, 0x04, 0x0F, 0x18, 0x20, 0x10, 0x08, 0x14, 0x18, 0x96,
+                0x61, 0x6C, 0x67, 0x26, 0x64, 0x74, 0x79, 0x70, 0x65, 0x6A, 0x70, 0x75, 0x62, 0x6C,
+                0x69, 0x63, 0x2D, 0x6B, 0x65, 0x79, 0x0D, 0x04, 0x0F, 0x18, 0x20, 0x10, 0x08, 0x14,
+                0x18, 0x96,
             ]
             .iter(),
         );

src/ctap/pin_protocol_v1.rs

@@ -328,6 +328,9 @@ impl PinProtocolV1 {
         let token_encryption_key = crypto::aes256::EncryptionKey::new(&shared_secret);
         let pin_decryption_key = crypto::aes256::DecryptionKey::new(&token_encryption_key);
         self.verify_pin_hash_enc(rng, persistent_store, &pin_decryption_key, pin_hash_enc)?;
+        if persistent_store.has_force_pin_change()? {
+            return Err(Ctap2StatusCode::CTAP2_ERR_PIN_INVALID);
+        }
 
         // Assuming PIN_TOKEN_LENGTH % block_size == 0 here.
         let iv = [0u8; 16];
@@ -821,6 +824,28 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_process_get_pin_token_force_pin_change() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        set_standard_pin(&mut persistent_store);
+        assert_eq!(persistent_store.force_pin_change(), Ok(()));
+        let mut pin_protocol_v1 = PinProtocolV1::new(&mut rng);
+        let pk = pin_protocol_v1.key_agreement_key.genpk();
+        let shared_secret = pin_protocol_v1.key_agreement_key.exchange_x_sha256(&pk);
+        let key_agreement = CoseKey::from(pk);
+        let pin_hash_enc = encrypt_standard_pin_hash(&shared_secret);
+        assert_eq!(
+            pin_protocol_v1.process_get_pin_token(
+                &mut rng,
+                &mut persistent_store,
+                key_agreement,
+                pin_hash_enc
+            ),
+            Err(Ctap2StatusCode::CTAP2_ERR_PIN_INVALID),
+        );
+    }
+
     #[test]
     fn test_process_get_pin_uv_auth_token_using_pin_with_permissions() {
         let mut rng = ThreadRng256 {};
@@ -885,6 +910,30 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_process_get_pin_token_force_pin_change_force_pin_change() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+        set_standard_pin(&mut persistent_store);
+        assert_eq!(persistent_store.force_pin_change(), Ok(()));
+        let mut pin_protocol_v1 = PinProtocolV1::new(&mut rng);
+        let pk = pin_protocol_v1.key_agreement_key.genpk();
+        let shared_secret = pin_protocol_v1.key_agreement_key.exchange_x_sha256(&pk);
+        let key_agreement = CoseKey::from(pk);
+        let pin_hash_enc = encrypt_standard_pin_hash(&shared_secret);
+        assert_eq!(
+            pin_protocol_v1.process_get_pin_uv_auth_token_using_pin_with_permissions(
+                &mut rng,
+                &mut persistent_store,
+                key_agreement,
+                pin_hash_enc,
+                0x03,
+                Some(String::from("example.com")),
+            ),
+            Err(Ctap2StatusCode::CTAP2_ERR_PIN_INVALID),
+        );
+    }
+
     #[test]
     fn test_process() {
         let mut rng = ThreadRng256 {};

src/ctap/storage.rs

@@ -384,7 +384,9 @@ impl PersistentStore {
         let mut pin_properties = [0; 1 + PIN_AUTH_LENGTH];
         pin_properties[0] = pin_code_point_length;
         pin_properties[1..].clone_from_slice(pin_hash);
-        Ok(self.store.insert(key::PIN_PROPERTIES, &pin_properties)?)
+        self.store.insert(key::PIN_PROPERTIES, &pin_properties)?;
+        // If this second transaction fails, you are forced to retry.
+        Ok(self.store.remove(key::FORCE_PIN_CHANGE)?)
     }
 
     /// Returns the number of remaining PIN retries.
@@ -541,9 +543,18 @@ impl PersistentStore {
         Ok(())
     }
 
+    /// Returns whether the PIN needs to be changed before its next usage.
+    pub fn has_force_pin_change(&self) -> Result<bool, Ctap2StatusCode> {
+        match self.store.find(key::FORCE_PIN_CHANGE)? {
+            None => Ok(false),
+            Some(value) if value.len() == 1 && value[0] == 1 => Ok(true),
+            _ => Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR),
+        }
+    }
+
+    /// Marks the PIN as outdated with respect to the new PIN policy.
     pub fn force_pin_change(&mut self) -> Result<(), Ctap2StatusCode> {
-        // TODO(kaczmarczyck) implement storage logic
+        Ok(self.store.insert(key::FORCE_PIN_CHANGE, &[1])?)
-        Ok(())
     }
 }
 
@@ -1148,6 +1159,18 @@ mod test {
         }
     }
 
+    #[test]
+    fn test_force_pin_change() {
+        let mut rng = ThreadRng256 {};
+        let mut persistent_store = PersistentStore::new(&mut rng);
+
+        assert!(!persistent_store.has_force_pin_change().unwrap());
+        assert_eq!(persistent_store.force_pin_change(), Ok(()));
+        assert!(persistent_store.has_force_pin_change().unwrap());
+        assert_eq!(persistent_store.set_pin(&[0x88; 16], 8), Ok(()));
+        assert!(!persistent_store.has_force_pin_change().unwrap());
+    }
+
     #[test]
     fn test_serialize_deserialize_credential() {
         let mut rng = ThreadRng256 {};

src/ctap/storage/key.rs

@@ -88,6 +88,9 @@ make_partition! {
     /// board may configure `MAX_SUPPORTED_RESIDENT_KEYS` depending on the storage size.
     CREDENTIALS = 1700..2000;
 
+    /// If this entry exists and equals 1, the PIN needs to be changed.
+    FORCE_PIN_CHANGE = 2040;
+
     /// The secret of the CredRandom feature.
     CRED_RANDOM_SECRET = 2041;