The following is a very sketchy plan for a secure protocol for an anonymous server which allows replies without storing a recipient database in the clear. To send a message: The sender first exchanges keys with the sever (public key cryptography assumed), the server now has the users key and the user the servers. The user sends the server: The recipient for the message the message itself a password previously agreed The users ID on the server The server decrypts to get the above back in plaintext, then it encrypts the ID & the users address with a random session key and stores it in the database. notice nothing is stored in the clear the server now encrypts the session key with the senders public key, and fowards it to the sender of the original message. now finally the server sends the message onto the intended recipient in plaintext (who must also have exchanged keys with the server) along with the ID of the sender encrypted with the servers public key. the recipient responds with his reply, and the ID of the sender still encrypted in the servers Public key The server stores this When the user (the original sender) wants to pick up his mail after a couple of days he sends the server his ID encrypted with the servers public key, the server compares this with all of the encrypted IDs in the database and when it finds a match it fowards the corresponding mail to the original sender of the first message. Thats all folks. This system has 1 huge fault, we can encrypt a uses ID with the servers public key to see what his ID in the encrypted database is and therefore identify him, maybe we need two seperate server public keys, and when IDs come in encrypted with key1 (the one it releases) it decrypts with secretkey1 then encrypts with publickey2 (the one it keeps secret) or maybe we can just hash and sign the IDs in the database? as I said it`s very sketchy, I made most of this up as I wrote it so if you must tear it to pieces please do so constructively, it could be the route to a secure system.... Datacomms Technologies web authoring and data security Paul Bradley, Paul@fatmans.demon.co.uk Http://www.fatmans.demon.co.uk/crypt/ "Don`t forget to mount a scratch monkey" -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6 mQCNAjH9j+cAAAEEAMBvREiQR0ot9dFCO0TiSCSunAYLv2g1Bc6I3bz8FzKXNH53 6mieJf/W4rD+CxJpT0q9RQaaoRtkHJLwbjfK2il3D7mEahMAyqvF/xRJNqkXfhM3 sRJM0Jh43l+W0M5vwokbEbk25/bxWWGspTsLD3YHbzKnG6pOcL5OPIRbv66xAAUR tCdQYXVsIEJyYWRsZXkgPHBhdWxAZmF0bWFucy5kZW1vbi5jby51az4= =riHc -----END PGP PUBLIC KEY BLOCK-----