Which would be more difficult, reading the secret at some point before the memory was cleared, or reading it _after_ the memory was cleared, but _before_ the cache was overwritten?
The secrets stay in the cache much longer, and are rarely evicted to the heap at all.
Cryptographic operations can take hundreds of thousands of cycles during which the values can be freely read. The cache will stay stale after the values have been cleared for _longer_ than that?
At least one of the 3 caches will stay much longer, yes.
Esp. the L3.
Throwing a tantrum because of 50 cycles for the mb is laughable.
They should call it fast crypto, but not secure crypto.