Mintage: 50,000
The Royal Australian Mint released a limited edition fifty cent commemorative coin to celebrate the Australian Signals Directorate's (ASD) 75th anniversary.
In tribute to the importance of code breaking and evolution of signals intelligence, ASD experts collaborated with the Royal Australian Mint to design the coin’s unique cryptographic code. There were multiple layers of code on both sides of the coin, with a hidden message revealed after each layer was solved.