1. A document authentication system comprising: a document authentication device comprising a substrate and, on said substrate, a first transceiver and a first processor electrically connected to said first transceiver; and a document authentication program executable by a second processor of a computerized device, said computerized device comprising a second transceiver electrically connected to said second processor, said document authentication program causing said computerized device to establish a wireless communication link with said document authentication device when said first transceiver is adjacent to said second transceiver, said first transceiver receiving, from said second transceiver over said wireless communication link, authentication information for a document, and, said first processor using said authentication information to generate encoded data to be embedded in said document.