Replace MgmKey::set with MgmKey::{set_default, set_manual} (#224)

* Add MgmKey::set_default method

This wipes any metadata related to derived and PIN-protected management
keys, returning the management key to its default state.

* Transaction::set_mgm_key: Take touch requirement as bool

The Option<u8> was inherited from the original C code's usage of an
unsigned char. We don't need that flexibility, because only two cases
are supported.

* Replace MgmKey::set with MgmKey::set_manual

MgmKey::set_default is now implemented as a wrapper around
MgmKey::set_manual, as they both require clearing metadata related to
derived and PIN-protected management keys.

tests/integration.rs

@@ -114,10 +114,11 @@ fn test_verify_pin() {
 #[cfg(feature = "untested")]
 #[test]
 #[ignore]
-fn test_protected_mgmkey() {
+fn test_set_mgmkey() {
     let mut yubikey = YUBIKEY.lock().unwrap();
 
     assert!(yubikey.verify_pin(b"123456").is_ok());
+    assert!(MgmKey::get_protected(&mut yubikey).is_err());
     assert!(yubikey.authenticate(MgmKey::default()).is_ok());
 
     // Set a protected management key.
@@ -129,10 +130,19 @@ fn test_protected_mgmkey() {
     assert!(yubikey.authenticate(MgmKey::default()).is_err());
     assert!(yubikey.authenticate(protected.clone()).is_ok());
 
+    // Set a manual management key.
+    let manual = MgmKey::generate().unwrap();
+    assert!(manual.set_manual(&mut yubikey, false).is_ok());
+    assert!(MgmKey::get_protected(&mut yubikey).is_err());
+    assert!(yubikey.authenticate(MgmKey::default()).is_err());
+    assert!(yubikey.authenticate(protected.clone()).is_err());
+    assert!(yubikey.authenticate(manual.clone()).is_ok());
+
     // Set back to the default management key.
-    // TODO: This does not clear the previous key from the protected metadata.
-    assert!(MgmKey::default().set(&mut yubikey, None).is_ok());
+    assert!(MgmKey::set_default(&mut yubikey).is_ok());
+    assert!(MgmKey::get_protected(&mut yubikey).is_err());
     assert!(yubikey.authenticate(protected).is_err());
+    assert!(yubikey.authenticate(manual).is_err());
     assert!(yubikey.authenticate(MgmKey::default()).is_ok());
 }