Hardware reduces loss of encrypted data – Sandia National Laboratories researchers develop protected data communication hardware for use in top secret and theft-vulnerable applications
Researchers at Sandia National Laboratories have developed improved data communications hardware for preventing encoded information from being lost because of improper synchronization between the encryption and decryption processes.
The hardware is designed to operate at communications rates 25 times faster than present rates and detect synchronization losses up to 50 times quicker than alternative synchronization loss detection devices.
Information is encrypted or enciphered to protect it against disclosure. The technique is valuable not only in matters of national security but also in private enterprise in cases where theft, fraud, or other monetary loss could occur if the information were not protected. The electronic transfer of funds is perhaps the most common example of the latter situation.
Encryption is accomplished by including some special characteristic – a common algorithm – in the transmitting and receiving units to code and decode the information. Secrecy is maintained by having the keys to the coding method known only to the transmitter and receiver.
Communication circuits that are encrypted for protection against disclosure of information are rendered useless when the encryption and decryption processes are not synchronized properly. That is, when more or fewer computer information bits are received for decryption than were encrypted, cryptographic synchronization is lost, and subsequent decrypted data is garbled beyond recognition.
While some self-synchronizing algorithms exist, certain technical difficulties prevent their widespread use, necessitating devices to detect synchronization loss.
The problem of synchronization loss has become more common in recent years because current loss detection devices cannot operate reliably at the higher circuit speeds made possible by advanced technology. Some synchronization loss detection methods inject additional “overhead” data into the message in order to assure a recognizable pattern. The disappearance of this known pattern warns of synchronization loss.
Three members of Sandia’s Computer Communications Design Division – Lyndon G. Pierson, Joseph H. Maestas, and Thomas J. Pratt – have developed hardware that differs from alternate detection devices in that it looks for the absence of information patterns rather than specific patterns.
Because overhead patterns are not necessary with the Sandia hardware, more bandwidth is available for the communications process.
The Sandia hardware uses a series of electronic counters and comparators to determine that received data is “random,” or otherwise not coherent. This is made possible by measuring either the density of ones or the density of transitions between zeros and ones (bits) in the binary code. When the ones density (ratio of ones to total bits) or transition density (ratio of bit transitions to total possible transitions) reaches a certain range, the data is sufficiently random to be judged out of synchronization.
Pierson says the Sandia loss detector is being designed to operate at 50 megabits per second (Mb/s), compared to 2.048 Mb/s for the fastest known alternative. To date it has tested at 25 Mb/s. In addition to being faster and providing improved flexibility of installation, the Sandia hardware is more reliable and up to 50 times quicker at detecting synchronization loss at high communication rates.
The probability of finding expected patterns in unsynchronized data increases dramatically at highspeed communications rates (1 Mb/s to 50 Mb/s), Pierson says. “It is this increased probability of fooling current detection methods into falsely indicating that an encrypted circuit is synchronized that renders current methods useless at higher communication speeds,” he explains.
By quickly recognizing random data as unsynchronized, recovery can be initiated faster than by waiting to determine if certain data patterns have disappeared from the decrypted output stream. The latter method can take from 10 to 50 seconds while the Sandia hardware detects synchronization loss and begins recovery procedure within less than one second.
The Sandia method also eliminates the need to adjust for particular communication protocols processed by various encryption hardware. A good analogy for this is to think of the communications protocols as specific languages and the loss detectors as translators, Pierson says.
“The Sandia method is analogous to being able to recognize that human voices are communicating without having to understand the specific language used,” he explains.
The U.S. Department of Energy has been granted Patent No. 4,977,596 on the Sandia synchronization loss detection hardware.
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