Students better than a pro (bazeries) and an author (candela)

Cryptologia, Jan 1999 by Kahn, David

ADDRESS: 120 Wooleys Lane, Great Neck, New York 11023-2301 USA.

ABSTRACT: A cipher system proposed by a professional and solved half a century later by an amateur, who told of his success in a charming book, had been used a quarter century earlier as an exercise for student cryptologists.

KEYWORDS: Bazeries, Candela, Friedman, monoalphabetic substitution, French general staff

Rosario Candela was a successful New York City architect and an excellent amateur cryptologist. For several years after World War II he served as president of the New York Cipher Society, lecturing to the half-dozen members in his excitable, Italian-accented manner at evening meetings in his offices at 654 Madison Avenue. He owed his reputation in part to his 1938 book The Military Cipher of Commandant Bazeries: An Essay in Decrypting. An attractively designed and printed work (the result, no doubt, of Candela's publishing it himself) of 137 pages, it charms its readers with idiosyncratic opinions and entertaining digressions.

The military cipher of which he wrote was that of the successful and famous French cryptologist Major Etienne Bazeries. After the French general staff had turned down in 1891 what has come to be called the Bazeries cylinder (the inspiration for the U. S. Army's M-94 cipher device), Bazeries devised a new cipher. It was to meet the general staff's requirements of a system that would require only pencil and paper and that could be retained in memory without notes. He did not claim to have found an unbreakable system but did say that if three sample cryptograms that he submitted as tests could not be solved, he may have found the solution to the army's needs. The army requested an explanation of the system. He supplied it, together with another test cryptogram of 43 five-letter groups. It was a monoalphabetic substitution whose key changed each message with a transposition superimposed upon it and interspersed with some nulls. On 19 April 1899, the army declined the system, saying only that it "does not present sufficient guarantees of security to be adopted." Bazeries published this story in his entertaining 1902 book, Les Cha,ffes secrets devoiles ( "Secret Ciphers Unveiled" ), ending with a bitter query of how this reply could be reconciled with the failure to solve the 43-group cryptogram.

"The bibliography of cryptography shows that no attempt has yet been made to decrypt this pencil and paper cipher since its publication." He "succumbed to the temptation" of trying to gain through its solution "that measure of gratification which is the reward of any accomplishment." He succeeded. The Military Cipher of Commandant Bazeries describes his work, focusing on the solution of the 43-group message and giving the results as well of his solving the three earlier test messages. But, however charming the book is as an addition to the literature of cryptology, the system does not merit so exhaustive a study. William F. Friedman has said as much.

He may have based his opinion on something more than a general feeling that no monoalphabetic system can withstand cryptanalysis. In 1914, the Army Signal School at Fort Leavenworth, Kansas, was apparently instructing young signal officers in cryptology. Problem No. 5 described the Bazeries system on a mimeographed page and then gave the student cryptologists a sample cryptogram to solve. One worksheet is dated 11 December 1914 (a copy is in the folder Cipher Problems, Box 15, Bacon Cipher Collection, Manuscript and Rare Books Division, New York Public Library). Several of these problems were sent to the Riverbank Laboratories, a research institution in Geneva, Illinois, where Friedman was undertaking serious cryptographic work and where he quite likely saw them. Knowing that Bazeries' system was serving as an exercise may have given him his perspective on it. But one can only wonder what Candela would have thought had he known that his great effort had been matched a quarter of a century earlier by mere students!

BIOGRAPHICAL SKETCH

David Kahn, an editor of Cryptologia, is the author of The Codebreakers.