VIC cipher

VIC cipher

The VIC cipher was a pencil and paper cipher used by the Soviet spy Reino Häyhänen, codenamed "VICTOR".

FAQ

It was arguably the most complex hand-operated cipher ever seen, when it was first discovered. The initial analysis done by the NSA in 1953 did not absolutely conclude that it was a hand cipher, but its placement in a hollowed out 5c coin implied it could be broken by pencil and paper. The VIC cipher remained unbroken until more information about its structure was available.

Although certainly not as complex or secure as modern computer operated stream ciphers or block ciphers, in practice messages protected by it resisted all attempts at cryptanalysis by at least NSA (and perhaps other organizations such as GCHQ) from its discovery in 1953 until Häyhänen's defection in 1957.

A revolutionary leap

The VIC cipher can be regarded as the evolutionary pinnacle of the Nihilist cipher family.

The VIC cipher has several important integrated components, including mod 10 chain addition (a lagged Fibonacci generator, a recursive formula used to generate a sequence of pseudorandom digits), a straddling checkerboard, and a disrupted double transposition.

Until the discovery of VIC, it was generally thought that a double transposition alone was the most complex cipher an agent, as a practical matter, could use as a field cipher.

References

* David Kahn, [https://www.cia.gov/library/center-for-the-study-of-intelligence/kent-csi/docs/v05i4a09p_0001.htm Number One From Moscow]

External links

* [http://www.hypermaths.org/quadibloc/crypto/pp1324.htm John Savard's page on the VIC cipher]
* [http://users.telenet.be/d.rijmenants/en/ppc-xx.htm PPC-XX, a variant with four different keying methodes]
* [http://users.telenet.be/d.rijmenants/en/secom.htm SECOM, a VIC variant with extended checkerboard]
* [http://secretcodebreaker.com/history5.html "The Cipher in a Hollow Nickel"]

See also

* Topics in cryptography.


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