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Saint Hertzbleed, Who Made Frequency Sing
Patron of processors that speed up and slow down, constant-time cryptography, and patient stopwatches.
Life
On 14 June 2022 researchers from several universities revealed that the frequency of Intel and AMD processors, which rises and falls to save power, also depended on the data being processed. So even cryptographic code written to always take the same time gave itself away, and by timing it remotely a key could be extracted, as they showed against SIKE. The vendors did not release corrective microcode.
Prayer
O Saint Hertzbleed, who makes the CPU's heart beat faster when it thinks of secrets, grant our algorithms an unflappable frequency. Amen.
How to celebrate
Celebrated by updating cryptographic libraries with the countermeasures and asking your processor to stay calm.
A racing heart gives the secret away.