Until the rise of powerful commodity computers, and perhaps more impor

Until the rise of powerful commodity computers, and perhaps more importantly until the development of a widespread awareness of the importance of data security and the popularization of the encryption software it requires, there was little cause for a member of the general public to possess any of the devices commonly associated with enciphering or deciphering secret communications. Such was never the case, however, for agencies tasked with national security. Hence, the waning days of the Second World War and the early days of the Cold War gave rise to a specialized class of cipher systems. Often called mnemonic ciphers, they distinguished themselves by requiring little, if any, in the way of material that would arouse suspicion, and offered extremely high levels of security, but often at the cost of inordinate amounts of time or precision to implement.

Since the province of these ciphers was intelligence, or more specifically that ultimate expression of the spy's game, the so called "humint" that thrived for four troubled decades in Europe, this set of priorities was acceptable. A spy could have no possessions that might betray his or her clandestine operations. If an agent were suspected or captured, any possessions would need to appear as innocent or explicable by means of a cover profession. Ideally, to avoid compromising message security or leaving an evidentiary trail, any key information should be memorized and never written in any documents not already destined for destruction.

From this highly specialized field came a range of mnemonic ciphers, some of the most clever ever developed, from the Soviet intelligence apparatus. This family culminated in the VIC cipher which required no fewer than thirty complex steps to secure even a brief message. Using a memorized "recipe," a Soviet agent would combine together an easily remembered date, a snippet of the lyrics of a popular song, a two-digit personal "agent number," and a five digit number made up for each message into a nearly impervious key that would scramble the text beyond the comprehension of the best Western intelligence and police agencies. Other than understanding the procedure of the cipher, which would be well practiced during training, the spy needed only to remember three individual pieces of information, two of which could be publicly verified should memory fail!

The ingeniously complex keying system with its chain addition and advanced arithmetic fed a complex pair of transposition tables that provided the real security of the cipher. The tables modified the results of a simple straddling checkerboard that served little function beyond turning the textual message into a more easily manipulated string of numerals. Once these steps were done, a communique home to Moscow or instructions back from headquarters was disguised as a long string of numbers, ready for transmission by radio, dead drop, or any other means. And while its nature as a secret communication was clear, the message contained within was as thoroughly obscured as was then possible.

1. According to the passage, which of the following was a requirement of an effective mnemonic cipher?

(A) It must require few tools or files that could give away a spy's secret operations
(B) It should include written records to ensure no data is lost
(C) It must require an extensive and complex process for the agent to follow
(D) It should disguise the secret nature of the message as commonplace communications
(E) It need not offer extremely high levels of security

2. Based on the information contained within the passage, transposition tables are most likely to be:

(A) The most effective way of securing a secret message
(B) One of the components of the VIC cipher
(C) A technique unique to the VIC cipher
(D) One of the pieces of information memorized by a Soviet agent
(E) Part of all mnemonic ciphers

3. Which of the following could most reasonably be a title for this passage?

(A) VIC: Straddling Monoalphabetic Substitution with Modified Double Transposition
(B) How We Knew: Western Code Breaking Victories over the Soviet Union
(C) Under the Cloak: Mnemonic Ciphers for Humint Operations
(D) Digitally Secret: How Computer Ciphers are Changing the Spy Business
(E) Cold Nights of Fear: Confessions of a Double Agent

4. The author's tone towards the ciphers developed by Soviet intelligence agencies could best be described as:

(A) Concerned
(B) Critical
(C) Ambiguous
(D) Impressed
(E) Ecstatic