Implement all KeyStore methods except for password generation.

* Add all relevant message constants.
* Implement the messaging to send/retrieve key info.
* Implement _Flatten/_Unflatten for sending flat BKey objects.
* Remove application list from BKey, the key can't only differ by
  allowed applications as the identifiers would still collide, so the
  comparison isn't needed to uniquely identify the key. The applications
  can be enumerated via the BKeyStore instead.

headers/os/app/Key.h

@@ -73,14 +73,19 @@ public:
 			bool				operator==(const BKey& other) const;
 			bool				operator!=(const BKey& other) const;
 
+protected:
+	virtual	status_t			_Flatten(BMessage& message) const;
+	virtual	status_t			_Unflatten(const BMessage& message);
+
 private:
+			friend class BKeyStore;
+
 			BKeyPurpose			fPurpose;
 			BString				fIdentifier;
 			BString				fSecondaryIdentifier;
 			BString				fOwner;
 			bigtime_t			fCreationTime;
 	mutable	BMallocIO			fData;
-			BObjectList<BString> fApplications;
 			bool				fRegistered;
 };
 

headers/os/app/KeyStore.h

@@ -93,6 +93,10 @@ public:
 			status_t			GeneratePassword(BPasswordKey& password,
 									size_t length, uint32 flags);
 			float				PasswordStrength(const char* password);
+
+private:
+			status_t			_SendKeyMessage(BMessage& message,
+									BMessage* reply) const;
 };