Camouflage slider
The camouflage slide was a simple mechanical device that was used by the police in the Federal Republic of Germany from 1967 for encryption in analog radio ( BOS radio ). The camouflage slider was used for both letter-by-letter text encryption and the encryption of around 100 operational keywords and police-relevant terms. One of the 26 possible assignments for use was specified according to the cycle or on the current occasion and used until the next change specification.
Design
The camouflage slide, which was available in various technical versions with the same functionality, was approximately 11 × 16 cm in size and - depending on the version - a height between approximately 6 and 11 mm. An opaque plastic housing with printed letters, numbers and keywords had viewing areas in which printed panels could also be moved and the assignment of the codes in the viewing windows to the printed text could be changed.
Encryption of texts
For the encryption or decryption of texts , viewing windows were included to convert letters and digits using the very simple reverse Caesar encryption method . This encryption also specified the number of 26 possible assignments (from A – Z to A – A). The text had to be implemented in this way letter by letter and digit by digit. Due to the high time required for this manual process, text encryption was limited in practice to only a few incidents with short texts and a high need for confidentiality.
Encryption of operational keywords
The key words used were encrypted by assigning a number made up of three digits to the printed terms in viewing windows, coupled with the Caesar encryption. The number assigned to the term was simply read off. Accordingly, an event like “traffic accident” could be expressed using the current number out of 26 possible values. (With the setting as on the camouflage slide shown above, this would have been "069".)
meaning
In analog BOS radio, which has since been replaced by digital radio in the German police force , there was technically the simple possibility of listening to conversations on commercially available radio receivers (radios) in the VHF range - at least if the radio receiver was manipulated slightly. Technical concealment was expensive at the time and practically unaffordable as general police equipment.
Originally, police stations had different, regional code systems in use to conceal or also to shorten radio communications. The camouflage slide enabled standardization across the borders of the federal states. This seemed necessary because of the increasing need for cooperation, as it was during the time of RAF terrorism.
Announcements of texts over radio encrypted with camouflage sliders were limited to only a few individual cases because of the effort involved. The actual benefit of the encryption of operational keywords and other specified police terms using a camouflage slide is not quantifiable. At least it was not uncommon in various circles to overhear the police radio with radios or radio scanners and to evaluate findings. However, as a rule, only the relevant keyword was encrypted and the rest was spoken in plain text, so that the actual obfuscation effect was only slight in practice.
With the introduction of the radio reporting system in the 1980s and 1990s, which in any case obscured parts of the radio communications with radio telegrams, as well as with the decline in terrorism in Germany, the camouflage slider lost further importance. In digital radio, which includes end-to-end encryption , further encryption is not necessary.
Individual evidence
- ↑ Hamburger Abendblatt: Uniform "camouflage slider" for the police from January 1st. December 28, 1966, archived from the original ; Retrieved July 22, 2015 .
- ↑ Federal Agency for Digital Radio of Authorities and Organizations with Security Tasks (BDBOS): Chronicle of Digital Radio BOS. Retrieved May 17, 2019 .
- ↑ Federal Agency for Digital Radio for Authorities and Organizations with Security Tasks (BDBOS): BOS security cards. Retrieved November 8, 2016 .