Chaocipher

The Chaocipher is a <a href="/facts/Cipher/eJnuftYe">cipher</a> method invented by John Francis Byrne in 1918 and described in his 1953 autobiographical Silent Years. He believed Chaocipher was simple, yet unbreakable. Byrne stated that the machine he used to encipher his messages could be fitted into a <a href="/facts/Cigar_box/gD1j12DE">cigar box</a>. He offered cash rewards for anyone who could solve it.
Byrne tried unsuccessfully to interest the US Signal Corps and Navy in his system. Although numerous students of classical <a href="/facts/Cryptanalysis/7CPEQlJI">cryptanalysis</a> attempted to solve the challenge messages over the years, none succeeded. For 90 years, the Chaocipher algorithm was a closely guarded secret known only to a handful of persons.
In May 2010 Byrne's daughter-in-law, <a href="/facts/Patricia_Neway/Fpeo8zsa">Patricia Byrne</a>, donated all Chaocipher-related papers and artifacts to the <a href="/facts/National_Cryptologic_Museum/YeeusI2z">National Cryptologic Museum</a> in Ft. Meade, Maryland, USA. This led to the disclosure of the Chaocipher algorithm.

Chaocipher open-in-new

Chaocipher