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Blessed GoFetch, Who Fetched the Keys From the Prefetcher
Patron of Apple Silicon processors, over-eager prefetchers, and cryptographic keys in memory.
Life
In March 2024 a group of researchers from several universities presented GoFetch, an attack on Apple's M-series chips. A particular prefetcher, meant to guess which data will be needed, treated certain values as if they were addresses and loaded them ahead of time; by watching this behaviour, a malicious program on the same machine could reconstruct, little by little, the keys used by some cryptography libraries. The flaw is in the silicon, so it can only be mitigated with care in software.
Prayer
O Blessed GoFetch, who fetches what he shouldn't, teach our prefetchers not to touch the secrets. Amen.
How to celebrate
Celebrated by updating cryptographic libraries with the countermeasures and keeping secrets away from unwanted guests.
Fetch too much, and you bring back the secrets too.