Comey said he needs some way to read and listen to any communication for which he's gotten a court order. Modern end-to-end encryption — increasingly common following the revelations of mass surveillance by NSA whistleblower Edward Snowden — doesn't allow for that. Only the parties on either end can do the decoding.

Comey's problem is the nearly universal agreement among cryptographers, technologists and security experts that there is no way to give the government access to encrypted communications without poking an exploitable hole that would put confidential data, as well as entities like banks and power grids, at risk.

But while speaking at Senate Judiciary and Senate Intelligence Committee hearings on Wednesday, Comey repeatedly refused to accept that as reality.

"A whole lot of good people have said it's too hard … maybe that's so," he said to the Intelligence Committee. "But my reaction to that is: I'm not sure they've really tried."