August Kerckhoffs was a Flemish cryptographer most known for his famous list of six principles regarding good cryptography practices.
Born Jean Guillaume Hubert Victor Francois Alexandre Auguste Kerckhoffs von Nieuwenhof in 1835 in Nuth, Holland, the young man spent his formative years studying linguistics and poetry in Germany. He became very interested in word puzzles and ciphers, and upon graduating, became a professor of cryptography (then a relatively new field of study, though the art had existed for centuries) at the School of Higher Commerical Studies in Paris.
While teaching, Kerckhoffs became very interested in military cryptography. Through various enquiries throughout the Empire, he learned that as a general rule, the ciphers and keys used by current French intelligence were woefully inadequate, and based on security through obscurity. If one of the bearers of the code process was captured, it was only a matter of time before the key was broken and that code became useless.
In response, Kerckhoffs wrote two articles in le Journal des Sciences Militaires suggesting new principles for better codekeeping practices:
- The code should be practically unbreakable, if not theoretically so.
- The code should not be inconvenienced by revealing the details of the code. Only the key should be kept secret.
- The key should be memorable without notes and easily changed.
- The key should be able to transmit via telegraph. (This was to prevent codes of made-up letters and symbols.)
- The entire code encryption and decryption tools should be operable and portable via a single person.
- The code should not require lots of training or intellect to master.
These principles may seem rather obvious, but Kerckhoffs' Requirements are still quoted in cryptography books today. Kerckhoffs himself received two medals for his work.
In 1885, Kerckhoffs became a major proponent of an international language. He began working with several of his Dutch colleagues on implementing Dutch phrases and words into the Volapük system. He became Director of the Volapük Academy, and introduced the language into study programs in France, Spain, and Norway. Two years later, Esperanto had completely overrun Volapük and Kerckhoffs returned to his post as professor. He passed away in 1903, but his contribution to codebreaking and ciphers lives on even today in the modern age.