Secrecy is, of course, the most important consideration in the German plots in this country. When Bernstorff wished to arrange with Berlin to give Bolo Pasha ten million francs to betray his country, he naturally did not write out his messages in plain English for every wireless station on both sides of the Atlantic to read them as they went through the air. He did, to be sure, write the messages in English, and they looked plain enough—and innocent enough—but they meant something very different from what they seemed to mean. And when it got down to the actual transfer of the money, another German agent in New York signed the messages, which likewise were not what they seemed.
Those messages were in code. (They are reproduced and explained in this chapter.)
Now code should not be confused with cipher. When some Hindus in New York, subsidized by Berlin, wished to write their plans to some other Hindus in San Francisco, concerning their common purpose of fomenting revolution against British rule in India, they wrote out messages that consisted entirely of groups of Arabic numerals.
Those messages were in cipher.
To any one but an expert, many code messages look simple and harmless, and cipher messages usually look unintelligible and suspicious. Yet, oddly enough, the cipher messages are by far the easier to make out. Indeed, unless you have a copy of the code, code messages can almost never be translated, whereas a straight cipher message can almost invariably be unraveled by an expert, if you give him enough time and material. Hence, by people who know the subject (and nobody had mastered it so thoroughly as the Germans), codes are used for secrecy, and ciphers are used simply as an added precaution and to delay the unraveling of a message if, by any chance, the enemy has gotten possession of a copy of the code.
German plot messages, therefore, are usually written out first in plain German, then coded, and the code then put into cipher. Such messages are called enciphered code.
For an enemy to get them to make sense, he has first to decipher them, and then decode them. Any expert can decipher them—in time. Decoding them is a very different matter.
Before taking up some of the German code and cipher messages that have been translated, with dramatic results, it will be well to discuss codes and ciphers in general.
A code is an arrangement by which two people agree, when exchanging messages, always to substitute certain words or symbols for the real words of the message. Thus, they might agree on these substitutions: