Your spy skills could soon be put to the test by a new 50-cent coin covered in secret, coded messages.
The limited-edition commemorative coin will be released on Thursday to mark the 75th anniversary of the nation's foreign intelligence cybersecurity agency, the Australian Signals Directorate (ASD).
While the coin is not intended for circulation, 50,000 specialty coins will be available for purchase from the Royal Australian Mint, each featuring four levels of coded messages to crack.
ASD director-general Rachel Noble said the coin celebrated the work of the agency's members and the evolution of code-breaking.
"Back in World War II, our people, military and civilian, and mostly women … used pencil and paper to decode Japanese military codes, and then re-encode them to send them out to the allies to let them know where Japanese war fighters were," she said.
"We have used that part of our history in different layers, which represent the progress of encryption and technology through our 75 years."
Puzzle is a novel recruitment scheme
The coin serves a larger purpose than just being a fun puzzle to solve, with Ms Noble saying those who crack the codes could be "pretty well placed" to get a job at the ASD.
"We thought this was a really fun way to engage people in code-breaking with the hope that, if they make it through all four levels of coding on the coin, maybe they'll apply for a job at the Australian Signals Directorate."
It's not the first time a usually secretive government agency has opted for a very public way to recruit new employees.
In 2017, the Australian Secret Intelligence Service launched an online test with a series of scenario challenges, targeting the next generation of Australia's international spies.
Then, last year, the Australian Security and Intelligence Organisation used Instagram to unveil the secrecy surrounding the lives of contemporary spies.
Hints to decode the coin's secrets
The ASD says the coin's four different layers of encryption are each progressively harder to solve, and clues can be found on both sides of the coin.
Royal Australian Mint chief executive Leigh Gordon said cryptography experts had worked with the mint to design the coin, though he added that, even once the design was completed, fitting the codes on the faces of the coin was a complex process.
"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."
Ms Noble said that while there were no classified messages on the coin, those who crack the codes could discover "some wonderful, uplifting messages".
"Like the early code breakers in ASD, you can get through some of the layers with but a pencil and paper but, right towards the end, you may need a computer to solve the last level," she said.
