Review of Kahn
The codebreakers by David Kahn. Weidenfeld and Nicolson
The Musical Times, Aug. 1968 (p. 730) © the estate of eric sams
Chess, mathematics, music, and cryptography all belong together. The first three have their infant prodigies; and if infants took their wars as seriously as adults, so would the fourth. What have all four in common? Abstraction; a basic function of the human brain itself. Of course the child's mind wants to play; and these are natural fields for it to play in.
In particular, music and cipher are near allied. So this book is of special interest to born musicians; it shows that they may well be born cryptographers. After Pearl Harbour, American naval intelligence was desperately short of men; all they could find was one ship's band. But the bandsmen turned out to be nearly all above average at cryptanalysis, and some were exceptional. The brilliant Painvin, French cipher ace of World War I, was an excellent cellist; his British counterpart Hitchings was a music teacher. The American Mauborgne, outstanding in two world wars, was a violinist; so was the German expert Kunze. The critic and composer Francis Toye was recruited by the Admiralty's famous code-breaking (and epoch-making) Room 40. Elgar's cipher message to Dorabella  has baffled some of the best brains in the business.
The links are even closer than this. Mr Kahn's vade-mecum, though admirably complete in every other imaginable respect, is silent about Porta's music-cipher and its offshoots. He does however describe a splendid device for placing illegal bets, composed of "several sheets of music, neatly staffed and scored, complete with treble clefs, slurs and crescendo marks". A sound investment, evidently, with endless possibilities for composers. A flutter on St Leger lines for example sounds irresistible; and even the treble chance has its points. So to the closest link of all. Perhaps music actually is a form of cipher? Schoenberg thought so; he even feared it might one day be deciphered. Most of his own seems fairly secure at the moment; but earlier music is already cracking under the strain of analyses like Reti's or Schenker's. No wonder keys have had to be changed or abandoned. Now music is once again mysterious - indeed, some random systems may be the musical equivalent of the scrambler and the one-time pad, which are guaranteed to baffle the hostile listener or analyst. If by any chance these random notes are on the right lines, Mr Kahn's superlative book may turn out to be required reading for musicians of the future, as well as the fullest and finest cipher compendium of all time.
 see Edward Elgar, Memories of a Variation by Mrs Richard Powell, p. 89
 see e.g. The History of a Cipher by H. Neville Davies, M&L (1967), lxviii, 325-9