During World War II, Canada included a patriotic message on its 5-cent coins: We win when we work willingly. The slogan was in Morse code, flush along the rim of the reverse. While not obvious, neither was it intended to be secret. Rather, the message was an element of the propaganda effort. Another wartime effort was Canada’s use of tombac, an 88-12 alloy of copper and zinc to replace nickel on the 5-cent coins of 1942 and 1943. In our time, the US “Native American” (Sacagawea) dollars for 2016 honor the Code Talkers. At first, during World War I, Native American soldiers worked as telephone operators because it was unlikely that Germans (who did know English) would know their languages. In addition, the Americans quickly adopted slang of their own to add a layer of obfuscation. World War II was a much larger and longer engagement. In 1943, the total population of the USA was 136.7 million, of whom 9.2 million were in the armed forces. Although American civilians who were ethnically Japanese were placed in concentration camps, their sons were allowed to join the armed forces (and fight in Europe). So, of course, the military tapped a new generation of Native American Code Talkers. (Shown here is the reverse (proof) and obverse (business strike) of the 2016 Code Talkers commemorative One Dollar "Native American" (Sacagawea) coin. Although the Navajo Code Talkers are the best known among them, as a result of books and a recent movie, in fact, they came from over 30 tribes and nations. On the other side of the Atlantic the British were engaged in a “wizard war” against the Germans. Among their “boffins” were the codebreakers of Bletchley Park. The 2014 movie The Imitation Game told the story of Alan Turing and his failed romance with Elisabeth Clarke. Clarke was a brilliant mathematician, and an accomplished codebreaker. After the war, she took up a numismatics, largely as a result of her husband John Kenneth Murray’s collection of Scottish coins. In particular, several series of silver groats and gold “unicorns” were not well identified or sequenced as the weights and finenesses had changed during the reigns of James III and James IV. She figured it all out, publishing and delivering papers. (See “The Early Unicorns and the Heavy Groats of James III and James IV” in the British Numismatic Journal, Volume 40, Number 8, 1971 online here: https://www.britnumsoc.org/publications/Digital BNJ/pdfs/1971_BNJ_40_8.pdf) For her work, the British Numismatic Society granted her a John Sanford Saltus Gold Medal in 1986, the only time that the medal was awarded to someone working exclusively with Scottish coins. Here in the USA today, computer security professionals have taken up the military challenge coin; and included codes, ciphers and hidden messages in them. According to the SANS Institute: "The Coin, Round Metal Object (RMO), is designed to be awarded to those who demonstrate exceptional talent, contributions, or helps to lead in the digital forensics profession and community. The Coin is meant to be an honor to receive it; it is also intended to be rare. Those who join the Lethal Forensicators Unit will have all privileges and recognition.” Shown here are two coins from the Austin, Texas, chapter of OWASP (Open Web Application Security Project) conventions. The red one is from an annual "B-Sides" spring meeting and the blue is from an annual autumn LASCON (Lonestar Application Security Conference) meeting. The coins were awarded to those who cracked the codes and hidden messages on the convention name badges.