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⚔ Commemorated today: The Siege of Tallinn (2007)Blessed Pathfinder, Reader of Roads Taken
Patron of branch predictors, JPEG images decoded in secret, and processors that remember every fork in the road.
Life
At ASPLOS 2024 a team of researchers led by UC San Diego presented Pathfinder, an attack on the conditional branch predictor of modern processors. By reading and manipulating the path history the CPU keeps to guess the future, one could reconstruct which road another program had taken, and from that infer secret data: in the demonstrations, AES keys and even images being decoded. Intel and AMD published their own advisories.
Prayer
O Blessed Pathfinder, who follows the processor's footsteps at every fork, let our secret programs walk without leaving tracks. Amen.
How to celebrate
Celebrated by writing constant-time cryptographic code, which always takes the same road whatever the secret.
Tell me the road you take and I'll tell you what you hide.