We tend to think of traffic analysis as a modern technique, but it's actually quite old. Here is a message from a spy, observing the activities of two of (English Queen) Elizabeth I's courtiers, whom he suspected of trying to manipulate her successor:
many secret meetings are made between them, where, after serious consults, they dispatch messengers and packets of letters, this sometimes twice in a week. This was in 1602. --Steven M. Bellovin, http://www.cs.columbia.edu/~smb --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]