A 50 cent coin cloaked in layers of secret code has been released to mark the 75th anniversary of the Australian Signals Directorate, responsible for signals intelligence, cyber warfare and cyber security. ASD's cryptographic experts collaborated with the Royal Australian Mint to help design the coin, which has four unique layers of code that - if broken - contain special messages about ASD. Fifty thousand coins have been produced and available for purchase by coin collectors and the Australian public. Australian Signals Directorate director-general Rachel Noble said the release of the coin was a fitting tribute to its work. "ASD has a long history that all Australians can be proud of, helping to protect the nation from foreign threats, and keeping us safer by preventing and disrupting online threats including cyber criminals," Ms Noble. "This exciting coin release challenges Australians to engage with the sorts of problem- solving that our talented people at ASD do every day, and might even be a pointer to a new career with us for those who can crack it." Royal Australian Mint CEO Leigh Gordon said developing the coin was a complex task as it was critical each different code was clearly identifiable. "While the 50 cent piece is Australia's biggest coin, it still doesn't have a lot of surface area," he said. "Ensuring people could see the code to decrypt it was one of the challenges our people were able to solve with ASD, to create a unique and special product." READ MORE: Collectively the ciphers showcase ASD's historical evolution as an organisation, combining codes thousands of years old through to modern binary code, invented during the age of computing. "Though some coding for the coin originated with the Roman Empire, there is remarkably still a place for them in modern intelligence," Ms Noble said. "I am immensely impressed by the people who work at ASD and this coin celebrates their work, as well as giving all Australians a glimpse of our history of protecting the nation from harm." "If you love puzzles and solving problems, and if you can discover the messages on our 75 th anniversary coin, then a career at ASD may be just what you're looking for." The coin can be purchased online through the Mint here. We've made it a whole lot easier for you to have your say. Our new comment platform requires only one log-in to access articles and to join the discussion on The Canberra Times website. Find out how to register so you can enjoy civil, friendly and engaging discussions. See our moderation policy here.