This package implements a Time-Based encryption system. A Message is encrypted using the public key of the recipient and a "Time Ticket" which is a short-lived public key generated by a "Time-Authority". The recipient can decrypt the message if, and only if the "Time-Authority" owning the private key of the "Time Ticket" "signs" the private key of the recipient. As the "Time-Authority" usually revokes the "Time Ticket" destroying the associated private key, signatures will become impossible after a "Time Ticket" has been revoked. This cryptosystem is especially useful for defending people against omnipotent power, for example oppressive government or "law enforcement". For example: The UK Law-enforcement seizes computer(s)/laptop(s) from animal rights activists and wrings their decryption keys and passwords from them. They're unable to decrypt (most of) the recipient's messages, since the Time-Tickets of those messages have already expired, an no one owns the associated private keys any more. Even if the "Law-enforcement" seizes the Time-Authority, it could not gain access to these messages anymore, since the wanted keys simply don't exist at this point.