According to recent press reports, the CIA and the BND secretly acquired Swiss crypto machine manufacturer Crypto AG and sold backdoored encryption technology.

A recent TV documentary reported on a spy radio transmitter that was placed near an East German army facility. The transmission schedule of this device was computed with a method that is not publicly known. Can a reader reverse-engineer this algorithm?

US military technician Brian Regan was sentenced to life in prison, after he had tried to sell secret information to foreign governments. He used a few interesting ciphers.

In 1970 the corpse of a woman was found near Bergen, Norway. In her car police found encrypted notes. These notes were deciphered, but the identity and the cause of death of this woman have remained a mystery until today. Thanks to blog reader Bjarne, I can now present a few new facts about this…

In 1944 a Nazi spy located in New York sent encrypted messages via Paris to Germany. These cryptograms have never been deciphered.

A German spy captured in the UK in World War II used a cipher that would hide a message in a love letter. Did this method work well in practice?

Frank Foley, a British secret agent operating in Nazi Germany, saved many Jewish people from the holocaust. In the British National Archives, I found an unusual encryption method that was (probably) used by one of his men.

In the 1950s the Germans used a unique crypto device named “Violine”. I have always wondered what it was used for. In a book about espionage I found the likely answer.

A Rubik’s Cube can be used to implement a highly secure encryption method.

In 1970 the corpse of a woman was found near Bergen, Norway. The real identity of this woman and the cause of her death are still not clear to date. In her car police found encrypted notes. According to Norwegian media, new evidence has now been discovered.