Regardless of when the code or cipher was invented, the techniques for deciphering were based on mathematical systems. In a cipher, every letter of the original message was replaced. Once the key to unraveling a cipher was found, the entire system was broken, and any message written using the cipher could be easily read.With a code however, this was not the case. Codes were not based on replacing every letter— in effect, creating a new alphabet—but on a code dictionary, or codebook. One word or phrase might be decoded, but the rest of the code dictionary would remain secure. The major weakness of a code over a cipher was that the codebook could be stolen, thus exposing the entire code.On impulse, she picked up the codebook and the newspapers with the ACE advertisements and sat down at her desk. Pulling a piece of paper toward her, she began checking the line of code against the entries in the codebook.Minutes later she stared at the result, which was utter gibberish.Unwilling to give up she began working to “decipher”
