TIL about the “Free Speech Flag”: https://en.wikipedia.org/wiki/Free_Speech_Flag
It’s an encoding of a secret key – 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 – that was used to copy protect HD DVDs and Blue Ray discs in the mid-2000s. This key was considered a so called “illegal number” since publishing it was tantamount to breaking a legally protected encryption scheme.
The flag consists of five colours whose RGB hex values are the first 15 bytes of the secret key and the C0 is printed in the lower right.
Mark Reid
@mdreid@mastodon.social
Work: Machine Learning Engineer at Apple, previously a Research Fellow in learning theory at the Australian National University. Play: #trailrunning, #marathon, #eurorack, #jazz, #guitar, #piano, #bass, #snowboarding, #gogame, #photography Based in Canberra, Australia 🇦🇺.
mastodon.social
Mark Reid
@mdreid@mastodon.social
Work: Machine Learning Engineer at Apple, previously a Research Fellow in learning theory at the Australian National University. Play: #trailrunning, #marathon, #eurorack, #jazz, #guitar, #piano, #bass, #snowboarding, #gogame, #photography Based in Canberra, Australia 🇦🇺.
mastodon.social
@mdreid@mastodon.social
·
Mar 27, 2026
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