Seth Rosenblatt/CNET

STANFORD, Calif. -- The director of the National Security Agency has a message for Silicon Valley: We come in peace.

Adm. Michael Rogers' attempt at rapprochement on Monday comes as tech firms are working to repel government surveillance after spying documents were leaked by Edward Snowden in June 2013. Apple and Google announced in September that the latest versions of their iOS and Android mobile operating systems, which power the vast majority of smartphones around the world, will be encrypted by default. Encryption hides the contents of a message so only authorized people can read it.

"It doesn't do us any good to villainize either side of this argument," Rogers said to about 100 professors, students and reporters at Stanford University. "Reasonable people can come to different conclusions about what is appropriate and not appropriate."

Rogers visited the home of most of the world's dominant tech companies for the second time since taking the reins of the NSA seven months ago. He told attendees he would visit California's tech hub twice a year and promised potential hires that the NSA offered rewards that neither Google nor Apple could match.

"We're going to give you the opportunity to do some neat stuff you can't do anywhere else," he said. "We're going to give you responsibility early, that's part of our culture."

Rogers' appeal comes amid rising tension between Silicon Valley and the US government. Documents made public by Snowden led to a series of spying revelations that have soured relations between tech companies and government agencies.

Tech firms have beefed up their implementation of encryption to prevent agencies from spying on customers without warrants. Google and Yahoo said last summer they are working on tools to encrypt web-based email, which is notoriously difficult to keep confidential.

In response, government agencies have accused leading tech firms of helping criminals and terrorists. Federal Bureau of Investigation Director James Comey last month encouraged tech companies to build back doors that would let government agencies view encrypted content. Today, Robert Hannigan, the new director of Britain's top spy agency, the Government Communications Headquarters, wrote in the Financial Times that Internet technologies are used as " command-and-control networks of choice" for terrorists.

Rogers took a less strident tone, acknowledging that tech firms might have good reasons for responding the way they have. Like his counterpart at GCHQ, he called for a "broader dialogue" about what "privacy means in the digital age."

The US conducts its surveillance operations differently from countries such as China and Russia, Rogers said. These countries "use the power of the nation-state" to infiltrate privately-held companies and acquire corporate secrets so they can use those secrets to improve companies back home, he said.

"I don't go into foreign companies, steal intellectual data, and pass it to" American companies, he said.