Verification of the source of program information in a conditional access system

A head end transmitter for creating verifiable programming information that is transmitted within a cable television system, the head end transmitter comprising:

• a control word generator for generating a control word;
• a device for securely maintaining a shared secret;
• a processor for performing a secure hash function having inputs of said control word, said shared secret, and said programming information, for creating a source authentication from at least a portion of an output from said secure hash function;
• and
• a transmitter for transmitting said source authentication, said programming information, and said control word.

A cable television system for verifying the source of programming information, the cable television system comprising:

• a programming source for providing inputs of a shared secret, a control word, and said programming information to a secure hash function, for receiving as an output thereof a source authentication, and for encrypting and transmitting said inputs and said source authentication;
• a receiver for receiving said source authentication and said inputs, creating a receiver authentication from at least a portion of an output of a secure hash function having inputs of said shared secret, said control word, and said programming information, for comparing said source authentication with said receiver authentication, and for accepting the programming information as authentic when the two are the same;
• and
• a transmission medium over which said transmission is broadcast from said programming source to said receiver.

A method of verifying a source of information in a conditional access system with a source and a receiver, comprising the steps of:

• using as inputs to a secure hash function system information, a control word, and a secret key, the secret key being shared by the source and the receiver and the control word being a key used in decrypting encrypted information and data transmitted over the conditional access system;
• performing the secure hash function at the source and using at least a portion of the output of the secure hash function performed at the source as a source authenticator;
• performing the secure hash function at the receiver and using at least a portion of the output of the secure hash function performed at the receiver as a receiver authenticator;
• and
• comparing at the receiver the source authenticator and the receiver authenticator and verifying the source of information in the conditional access system as the source if the source authenticator and the receiver authenticator match.