FBI forensic expert Stephen Flatley has lashed out at Apple during yesterday’s International Conference on Cyber Security in Manhattan, calling its engineers “jerks” and “evil geniuses” for making the bureau’s investigative work harder with strong encryption on iOS devices.

Motherboard reports that Flatley appeared to take issue with recent changes Apple made in order to make password attempts using a brute force method slower, changing the hash iterations from 10,000 to 10,000,000.

He said:

Your crack time just went from two days to two months. At what point is it just trying to one up things and at what point is it to thwart law enforcement? Apple is pretty good at evil genius stuff.

He praised Israeli company Cellebrite, which is thought to have helped the FBI crack the San Bernardino shooter’s iPhone 5c, for its alleged ability to counter Apple’s security protections.

“If you have another evil genius, Cellebrite, then maybe we can get into that front,” he said, facetiously coughing as he said “Cellebrite.”

Earlier in the week, FBI director Christopher Wray called encryption an “urgent public safety issue.” Apple and many other technology companies have long insisted that encryption protects their customers from hackers and authoritarian surveillance.