Computer chips have advanced to the point that they’re no longer reliable: they’ve become “mercurial,” as Google puts it, and may not perform their calculations in a predictable manner.
Not that they were ever completely reliable. CPU errors have been around as long as CPUs themselves. They arise not only from design oversights but also from environmental conditions and from physical system failures that produce faults.
But these errors have tended to be rare enough that only the most sensitive calculations get subject to extensive verification if systems appear to be operating as expected. Mostly, computer chips are treated as trustworthy.
Lately, however, two of the world’s larger CPU stressors, Google and Facebook, have been detecting CPU misbehavior more frequently, enough that they’re now urging technology companies to work together to better understand how to spot these errors and remediate them.Source: The Register
“One of our mercurial cores corrupted encryption,” he explained. “It did it in such a way that only it could decrypt what it had wrongly encrypted.”
They also have a short talk (~10 minutes) where they explain what happend.