XOR encoded document for secure message exchange

摘要

An XOR (exclusive or) encoded document is disclosed for establishing a joint secret between two parties. Encoded on the document are one or more areas of XOR messages. Each area containing an XOR message hides from view on each side of the XOR encoded document a different message on either side of a transparent base layer. To uncover a message in an area containing an XOR message on one side of the transparent base layer, the message on the other side of the XOR encoded document is scratched off and rendered illegible.