Code Breaking in Law Enforcement: A 400-Year History

Article excerpt


In February 2004, 11-year-old Carlie Brucia was abducted and murdered in Sarasota, Florida. While in a county jail awaiting trial, the suspect in the case, Joseph Peter Smith, wrote an enciphered message to his brother (Figure 1). The seemingly random series of symbols and numbers was sent to the FBI for analysis. The FBI determined that Smith enciphered the message by replacing letters of the alphabet with a series of one- or two-character combinations of numerals and symbols. To further complicate decryption, he wrote the message from right to left, starting at the bottom of the page and working his way up. Despite these obstacles, FBI cryptanalysts were able to quickly decipher the message, which contained incriminating references to hiding evidence and moving the body. On November 17, 2005, the jury convicted Smith in the abduction and murder of Carlie Brucia.


Cryptanalysis is the art of solving secret codes and ciphers. In courtrooms throughout history, cryptanalysis has played a key role in bringing criminals to justice. This article provides a historical overview of the role cryptanalysis has played in major cases over the past 400 years.

The Unabomber, 1978-1996

It is well known that criminals use codes and ciphers to communicate to others. However, when the Unabomber, Theodore Kaczynski (Figure 2), documented his deeds, it was not intended for anyone but himself. Kaczynski kept notebooks in which he logged his crimes, his feelings about them, and detailed plans for future crimes. These notes were found in a handwritten numerical code that he used to disguise his writing, which was in both English and Spanish (Birch, personal communication, 2005; Gibson 2000). His attempts at secrecy proved futile, however. When he was finally identified, the case against him was sealed by the decryption and translation of the content of those notebooks.


The Zodiac Killer, 1966-?

Unlike the Unabomber, who did not want his cryptic notations to be made public, the notorious Zodiac killer demanded that his ciphers be published in public newspapers. He thrived on the notoriety that the messages brought and even boasted of the strength of his ciphers. Despite his claims, Zodiac's most famous cipher (Figure 3) was broken within a few hours by a husband and wife team of amateur code breakers. Other Zodiac ciphers remain unsolved, and the Zodiac killer has never been brought to justice.


The Hollow Nickel Case, 1953-1957

The inner workings of a Soviet spy ring were uncovered with the crack of a nickel by a Brooklyn newspaper delivery boy. When the unsuspecting boy dropped the nickel on the sidewalk, it split apart to reveal a microphotograph with a series of numbers (Figure 4). The numbered code, the product of a Soviet one-time pad encryption system, was not broken until 1957, after Soviet KGB officer Reino Hayhanen defected to the United States. The information he provided on Soviet codes and cryptosystems helped the FBI Laboratory break the code. The discovery of the hollow nickel and its contents eventually led to the conviction of a Soviet spy best known by his alias Rudolf Abel. In 1962 Abel was exchanged for American pilot Francis Gary Powers, whose U-2 spy plane had been shot down over the Soviet Union two years earlier (Federal Bureau of Investigation n.d.; Federal Bureau of Investigation 2004).


A Family of Cryptanalysts: William and Elizebeth Friedman

In 1937 the Canadian government requested the services of an American cryptanalyst to decipher messages written in Chinese by members of a suspected opium-smuggling ring. Five suspects from Vancouver, British Columbia, were found guilty of trading ammunition and guns for opium (National Security Agency n.d.; U.S. Coast Guard 2002). The cryptanalyst that the Canadians sought was Elizebeth Friedman. …