One-time pads (OTPs) are used to encode/decode agent communications. They are issued in matching sets of two: one pad of sheets for the encoder and a matching pad for the decoder. No two sets and no two sheets within a set are alike. Each sheet contains a random key in the form of five-digit groups. Once a sheet has been used to encode a message, it is torn off the pad and destroyed. Encryption by OTP is virtually unbreakable.
OTPs can be made of paper, silk, or highly flammable cellulose-nitrate film that can be destroyed quickly and easily in an emergency. They can be as small as a postage stamp.
10 cm x 6 cm
(L x W)