Scientific Atlanta Inc has licensed RSA Data Security Inc’s encryption technology for inclusion in its PowerKey digital conditional system. PowerKey is an access control and security system and is under development for use in television set-top boxes, head-end components, cable modems and network management software. PowerKey will combine public key and secret key cryptographic methods to provide confidential delivery of broadcast, multicast and interactive services across broadband networks. Scientific Atlanta sees the unique advantage of its product lying in its use of public key encryption. Public key is a method of exchanging authenticated secret messages without previously exchanging secret keys. Instead of using the same key to encrypt and decrypt the data, RSA uses a mathematically matched pair of keys for encryption and decryption. What one encrypts, the other can decrypt. Public key enables having conditional access mechanisms to be in the set-top box itself, generating a key that neither the manufacturer, the end user nor anyone in between need know. Scientific Atlanta said that once the private key is known, the the public key can’t be discovered because the RSA algorithm between the two keys prevents this – mathematically, to discover the private key would require the factoring of a number greater than 230 digits long into its two prime factors. Traditional private key only systems mean someone has to be the holder of those keys. And this is potentially insecure, Scientific Atlanta said. When the technology hits the market depends on the deployment of digital set-top boxes, which it expects to be around mid-1997. Scientific Atlanta does not expect to include PowerKey in any of the interactive television trials, other than on a technical test basis, because those trials have between 1,000 and 4,000 users. That’s not enough to raise security issues, asserts Bob Van Orden, product line director for digital set-top boxes.
