Magical Alphabet - a question

This is my first post here, so I'd like to greet everyone!

I need to decipher a magical alphabet which was used on the Old Prussian Flag of Widewuto.

The flag can be found on wikipedia - I am SORRY for such an unreliable source, but as a new user I cant post links.

However, the information from wiki will suit us fine this time!

I have been informed that the alphabet used on the flag is probably some Renaissance (or late Middle Ages) magical alphabet.

Maybe some of you know what alphanet it is exactly? Where it was used? What letters are represented by the signs?

Thanks, any help appreciated! Regards to everyone