Serial communication is a communication technique used in telecommunications wherein data transfer occurs by transmitting data one bit at a time in a sequential order over a computer bus or a communication channel.

A remote user authorization verification system including a central device having data imput and output, memory and data comparison facilities, and a plurality of hand held, pocket size remote units arranged for data communication with the central device by means of conventional telecommunications devices, such as a telephone, the pocket size remote units having information input keying apparatus, memory apparatus and enciphering apparatus and being operative for providing an enciphered verification code to the central device for verification of the authorized status of the user. This application is a continuation, of application Ser. Ibm rational requisitepro crackers. 454,180, filed Dec. 28, 1982, now abandoned.

FIELD OF THE INVENTION The present invention relates to data communications generally and more particularly to apparatus and techniques for providing an indication of the authorized status of users of data communications systems. BACKGROUND OF THE INVENTION With the advent of increasingly widespread computer usage, data communications have become a part of the daily lives of a significant and growing portion of the population. In the conduct of such data communications, particularly for such activities as banking by telephone, positive identification of the user becomes imperative.

Various techniques have been proposed for providing positive identification of users of data communications and processing systems. 3,594,727 describes a credit card banking system in which a peripheral terminal receives separate identification codes from a credit card and from a secret number punched in by the customer. These codes are transmitted to a central location that verifies the pairing. 3,798,605 describes a multi-terminal data processing system including apparatus for verifying the identity of subscribers and includes two embodiments. In one embodiment, termed a 'password' system, all data or information originating at the terminal under use of the subscriber is enciphered in combination with the unique subscriber key. In the second embodiment, termed a 'handshaking' system, the user and the central processor exchange a plurality of messages, each formed by a combination of new and prior received data, identifying the subscriber. 3,764,742 describes a cryptographic idetification system which employs a 'credit card' having a personalized read only storage device implemented thereon.

The card holds the read only storage associated logic and devices to utilize the read only storage to generate pseudo-random strings of code data. The pseudo-random code is mixed with data which may be transmitted to a computer. The computer contains a pattern of the user's individual read only storage and it operates in sequence to generate the same pseudo random string of bits to decrypt the mixed encrypted data from the user. Buescher grand trombone serial numbers.