Electronic gibberish keeps data secret

Press, 19 February 1986, Page 38

Electronic gibberish keeps data secret

By

STEVE CONNOR

of

the “Observer” Fraud worth millions of pounds can be perpetrated by wily computer specialists intercepting financial data being sent down telephone lines from one bank to another. But their days of thieving are numbered. British Telecom is about to launch a scrambler that will make the German Enigma system look like English. BT has long been aware that computer data has been accessible. A team of nine scientists from its Martlesham Heath research laboratories has developed a device that turns information into gibberish before it is transmitted. A device at the receiving end turns the nonsense back into the original message. The device is a chip called B-crypt which, says BT, it hopes to launch later this year. The chip will be built into some of BT’s own products, and the company hopes to make it available to other manufacturers of telecommunications equipment or computers. B-crypt uses an encryption algorithm — or coding process — developed by BT and called Bl 52. The team from Martlesham placed this on to a chip that fits neatly and unobtrusively into a computer terminal. The sender and recipient of the data agree to use a particular code or “key” known only to them. The key and the algorithm in the chip then turn the message into a cipher that will appear as junk to anyone who inter-

cepts it. The lawful recipient uses a similar key to decipher the encrypted message.

Even if the encryption algorithm is known to a third party, the transmitted message will remain a mystery because the eavesdropper will not know which key the sender and recipient have agreed to use. The key can be changed at any time, given the consent of both parties. When only two people send and receive information and when the key is changed routinely in a pre-determined sequence known only to them, the system is called a “onetime pad.” This was the method of encryption used by the spy Geoffrey Prime, and by the hot-line between Washington and Moscow — which is a teleprinter, not a telephone as most people think.

B-crypt, however, is not a one-time pad. It is built so that many senders and receivers can use the

same system for transmitting their messages. Bcrypt is, in theory, possible to crack, but only if sufficient computational muscle were to be put into the task — something probably beyond the power of most organisations. BT was driven to develop B-crypt through the poor availability in Europe of what has until now been the only encryption chip available for commercial purposes, the Data Encryption Standard (DES) chip. The patent for DES is held by IBM, which means that buyers in Europe have to supply extensive details to the United States Government explaining what the DES chips will be used for.

Many European companies, fearing competition, are understandably reluctant to do this.

BT says that B-crypt is based on the same mathematical principles as DES, but that “the cryptographic configuration is

sufficiently different that it does not infringe on IBM’s patent.” The company says Bcrypt is superior to DES because, whereas DES is designed to work best within a computer system, B-crypt is better designed to encrypt information that is transmitted from one computer to another. Data sent over telecommunications lines has many repetitive elements which are used as addressing information, or “headers.” The same repetitive block of information will, with DES, be encrypted in the same way, so giving clues to an analyst. But B-crypt codes each repetitive element in a different way, thereby making the transmitted message more secure. — Copyright.