[hypest]

I'm referring to the "friend-space", where info is public but only among these friends. I want to share stuff with my friends, and FB seems a rather good technology for that!

The public key is used for encryption, not decryption, so anybody can have it...To read a message I send you, you use your private key. The message will be encrypted by me using your public key. So, any friend can send me a message but only I can read it. If more friends are to be able to read the same message, the string must actually include an instance of the message, encrypted with the "other" friend's key.