Raytheon Co. won a $31.1 million contract to design lighter, power-efficient devices that the U.S. military uses to securely transmit voice and data traffic. It is the first technology upgrade to the shoebox-shaped devices in more than two decades. These devices are portable and can be used in a variety of airborne, land, and maritime combat situations. Under a multiyear agreement, Raytheon will replace stand-alone cryptographic units with affordable, modern products that use data-scrambling algorithms to encrypt information on one end and then decrypt it on the other. Known as VACM, for VINSON/ANDVT Crypto Modernization, the program sets new standards for encryption performance and ease of use.