by Herbert O. Yardley
The author headed the titular Black Chamber, a euphemism for MI-8, the branch of US Intelligence that dealt with ciphers, codes and “secret inks” through WWI and beyond, until the branch was summarily closed by a spectacularly naive and short-sighted Secretary of State. Hardley is a fine raconteur, detailing step-by-step the painstaking ways he and his staff decoded, for example, messages that were composed solely of long strings of five-digit numbers (which turned out to be references to a dictionary’s page and line numbers).
The decryption of the Japanese codes, too, considering the lack of available information on the language itself, is incredible. There’s a long stretch of intercepted and translated Japanese telegrams which I suppose Yardley included to make a political point, but which is a bit dreary, when all one wants is more info on how he cracked the codes. Aside from that, it’s fascinating, not only the code breaking but the period detail: how legions of typists and thousands of cards were needed in those days before computers or the level of government spying: letters and cables read as a matter of course, people followed and observed... And here we are whining about the Patriot Act.