Home News Stories 2006 April A 400-Year History of Cryptanalysis
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A 400-Year History of Cryptanalysis

Code Breakers
A 400-Year History of Cryptanalysis


Coded message from the “Zodiac” killer
A coded message of the “Zodiac” serial
killer that was broken by a California couple
in a few hours.

Ted Kaczynski—the infamous “Unabomber”—used them. So did Russian spies like Rudolf Abel. Not to mention John Wilkes Booth and Mary, Queen of Scots.

We’re talking about secret codes and ciphers...used in the commission of crime, espionage, and terrorism.

Find out how law enforcement broke these and other codes with “cryptanalysis” in Code Breaking in Law Enforcement: A 400-Year History in the new issue of Forensic Science Communications. The article was written by one of our own cryptanalysts, Dorn Vernessa Samuel, who works in the Cryptanalysis and Racketeering Records Unit in the FBI Laboratory.

Here are a few of the cases featured:

  • Murder He Wrote. While in jail awaiting trial for the 2004 murder of an 11-year-old Florida girl, Joseph Peter Smith sent his brother a coded message. Authorities asked us to analyze it, and our cryptanalysts quickly broke the code. It wasn’t easy: Smith had replaced letters of the alphabet with a series of number/symbol combinations written from right to left and from the bottom of the page going up. In the letter, Smith made incriminating references to moving the body and hiding evidence, and he was ultimately convicted of the crime.
  • All in the Family. Code-breaking pioneers Elizebeth Friedman and her husband William were considered the “greatest marriage in the history of cryptology.” Elizebeth, a Treasury Department cryptanalyst, unraveled bootleggers’ ciphers during Prohibition, solved a Chinese code that broke up an opium smuggling ring (even though she didn’t know the language), and helped settle a maritime dispute between the U.S. and Canada (see the article for the interesting details!). A U.S. Army cryptologist who coined the term “cryptanalysis”, William decrypted Japanese diplomatic messages during World War II and secret telegrams in the 1924 Teapot Dome Scandal that led to the resignation of top U.S. officials.
  • North versus South. Both Union and Confederate forces used ciphers during the Civil War. Confederates were less successful in figuring out Union codes, though, and started publishing them in Southern newspapers, imploring readers to break them. John Wilkes Booth and his conspirators supposedly used ciphers as well to coordinate plans to assassinate President Lincoln.

If you want to learn more on the subject of code breaking, including details on basic cipher systems and how to break them, see the article Analysis of Criminal Codes and Ciphers in a previous issue of Forensic Science Communications.

And direct your grade-school children to our Kids’ page, which has a secret message to decode for fun.