Leo Marks
Leopold Samuel Marks (born September 24, 1920; died January 15, 2001) was an English cryptographer and scriptwriter.Born the son of a antiquarian bookseller in London, he demonstrated his skill at cryptography from an early age by deciphering his father's secret price codes. As a teenager, he earned pocket money by setting the Times crossword.
Marks joined the Armed Services in January 1942, and went to Bedford to train as a cryptographer. His original and unorthodox mode of thought led to him being the only one of his class judged not good enough to be sent to Bletchley Park; instead, he was sent to a rival organization of the intelligence services, the recently formed Special Operations Executive (SOE). (Later, when his abilities became apparent to all, Bletchley Park personnel would refer to him as "one that got away".)
Marks played a major role in changing the dnagerously unreliable and insecure cryptographic methods used by SOE-London during its first few years, especially for communications with SOE agents on the Continent. These were primarily double transposition ciphers) using agreed poems as keys. Marks pressed for improvements in the construction and security of SOE cyphers and was eventually to gain agreement to considerable changes. Perhaps most notable were his re-invention of the "one-time pad", re-organisation of the poem cyphers, and by the recruitment of a special team (based at Grendon Underwood, Buckinghamshire) to cryptanlyse "indecypherables" (garbled messages which had to be read, lest the agent be required to retransmit and increase risk of capture). Marks also invented a new form of "security check" (a duress code) which is still classified.
To improve the security of emergency poem cyphers, his solution was to use original poems instead of famous ones. Many of these he wrote himself, the best known being that given to the agent Violette Szabo, The Life That I Have, which was used in the film made about Szabo, Carve Her Name With Pride (1958). The loss of literary quality was more than compensated for by the increased difficulty for the opposition in finding unpublished poems in published collections.
Marks was often angry at the carelessness he found in SOE. Early on, he suspected German penetration of SOE operations in the Netherlands, called by the Germans Englandspiel, but his suspicions were ignored and as many as fifty agents were unnecessarily captured, tortured or killed. Marks had briefed many of these agents himself, including his close friend 'Tommy' Yeo-Thomas.
He left SOE in 1946 and declined an offer of employment from SIS. He went on to write a number of marginally successful plays and films, including The Girl Who Couldn't Quite (1947), Cloudburst (1951), The Best Damn Lie (1957), Sebastian (1967) and Twisted Nerve (1968), and also the script for Michael Powell's intelligent and highly controversial Peeping Tom (1960).
Marks' book about his work in SOE - Between Silk and Cyanide: A Codemaker's Story 1941-1945 (HarperCollins, 1998) became an instant classic. His account of his difficulties in getting it published illustrate some of the lack of sense employed by those in charge of security, investigation and prosecution of security breaches, etc.
He married the portrait painter Elena Gaussen in 1966, a marriage that lasted until shortly before his death.