Noreen (machine)

A Noreen at the Bletchley Park Exhibition (2005)

The Noreen , British BID device designation BID / 590 was a British cipher machine for encryption by telex that the cryptographically secure session key method ( English one-time pad , short OTP ) used.

history

In contrast to the usual five-channel punched tape you can see here, the Noreen used (slightly wider) six-channel punched tape. The sixth channel was used to control (switch on / off) the key function. In this way, characters could also be transmitted unencrypted, such as AAAAA to identify the beginning of the saying.

The machine was used mainly by British and Canadian agencies from the early 1960s to the 1980s. In terms of cryptography, it was fully compatible with the older and much more voluminous Rockex from World War II . As with all OTP machines, the central component is a mixer that links the text ( plain text or ciphertext ) and the key on a punched tape ( random text ) using the exclusive-or link (XOR).

While the plain text may contain all characters of the ITA2 code (International Telegraph Alphabet ), i.e. except for letters , digits and some special characters , the ciphertext consists exclusively of the 26 capital letters of the Latin alphabet . This enables (e) the easy transmission of the encrypted telex over commercial communication networks.

The Noreen was used, among other things, in transatlantic communications between Canada and the United Kingdom .

Web links

Noreen in the Crypto Museum , accessed October 16, 2018.
Noreen at Jerry Proc , accessed October 16, 2018.

Individual evidence

^ Crypto Museum UK Cipher Machines , accessed October 16, 2018.

[1] Crypto Museum UK Cipher Machines , accessed October 16, 2018.