BATCO

BATCO, short for Battle Code, is a hand-held, paper-based encryption system used at a low, front line (platoon, troop and section) level in the British Army. It was introduced along with the Clansman combat net radio in the early 1980s and was largely obsolete by 2010 due to the wide deployment of the secure Bowman radios. BATCO consists of a code, contained on a set of vocabulary cards, and cipher sheets for superencryption of the numeric code words. The cipher sheets, which are typically changed daily, also include an authentication table and a radio call sign protection system.

BATCO is similar to older Slidex system. The use of BATCO is still taught to Royal Signals Communication Systems Operators as a back-up should secure equipment fail or be unavailable. It is also taught to Army Cadets and Combined Cadets as part of the Signal Classification qualification.

Messages in BATCO are first encoded into numbers using one of several vocabulary cards. The BATCO cipher is then used to encrypt the numbers into letters, which can be transmitted over unsecure channels. The process is reversed at the receiving end.

Each BATCO vocabulary card groups words needed for a particular function, so card changes are infrequent. Every vocabulary word on a card is assigned a two digit code. Some vocabulary card entries call for a fixed number of digits after the two digit code. For example, the code for ETA (estimated time of arrival) is followed by a four digit time of day. Each card in a set has a three digit number and there is always a code word on the card that means switch to card number xxx.

Each BATCO cipher sheet is composed of a double-sided sheet of about A5 size that fits in a specially made BATCO wallet. Each single side is usually valid for 24 Hours. The wallet has a slide that aids in reading the tables correctly.

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