Australian Signals Directorate 50c Coin Decrypted

[AppDefects]

Australian Signals Directorate (ASD) marked its 75th anniversary with a specially minted coin (now out of stock). The coin contains an encrypted message, which has since been solved. Here is one solution.

Source: https://eshop.ramint.gov.au/2022-aluminium-bronze-uncirculated-75-anniversary-australian-signals-directorate