Abstract: A method for transmitting verified notification messages from a service provider to a PID (personal information device) user. The method includes the step of registering a plurality of users and providing each of the users with respective public and private encryption keys. A message is then received from a first user of the plurality of users. The received message is signed with the first user's private encryption key. A signature of the message is verified by using the first user's public encryption key. The authority of the first user to transmit notification messages is then verified. The message is then resigned with the second user's private encryption key and transmitted to at least a second user of the plurality of users, wherein the second user verifies the signature by using the second user's public encryption key.