Google has worked hard to lock down the personal data it collects since revelations in the last year and a half about mass surveillance programs at the U.S. National Security Agency, company Chairman Eric Schmidt said.

The news of surveillance by the NSA and intelligence agency counterparts at allied nations has damaged the U.S. tech industry on “many levels,” with many Europeans now distrusting U.S. tech companies to hold on to their personal data, Schmidt said Friday at a surveillance conference at the Cato Institute, a libertarian think tank.

Schmidt learned of efforts by U.K. intelligence agency GCHQ to intercept traffic between Google data centers through a newspaper article, he told the audience. “I was shocked,” Schmidt said.

Google had envisioned a complicated method to sniff traffic, but “the fact that it had been done so directly ... was really a shock to the company,” Schmidt said.

After reporters showed Google engineers a diagram of the intelligence agency’s methods to tap links between Google data centers, the engineers responded with a “fusillade of words that we could not print in our family newspaper,” Washington Post reporter Craig Timberg said.

Google responded to the revelations by former NSA contractor Edward Snowden by spending a lot of money to lock down its systems, including 2,048-bit encryption on its traffic, Schmidt said. “We massively encrypted our internal systems,” he said. “It’s generally viewed that this level of encryption is unbreakable in our lifetime by any sets of human beings in any way. We’ll see if that’s really true.”