Suggestions for (semi) securing high-scores in Flash/PHP game

Question

...I have read a few threads on here that have discussed various methods and was just looking for some feedback on a proposed solution we came up with. In one of the thread

Answer 1

I don't see any advantage of using the solution, Kent mentioned. As a client, I can request that server side created key. Ok I can't use it more than one time, but i don't have to ... every time I need one i just request it.

1. So i request the key.
2. Make my own highscore
3. Hash the highscore with the key.
4. Send the highscore to server
5. The server use the submitted key to get the highscore back.