Edward Snowden speaks at SXSW

"Encryption makes bulk surveillance too expensive," Soghoian said. "The goal here is not to stop the government from going after legitimate surveillance targets. The goal here is to make it so they cannot spy on innocent people [just] because they can."

Soghoian, Snowden and Wizner also discussed ways to improve oversight of programs like PRISM and agencies like the NSA. Snowden said accountability was the key to keeping agencies like the NSA from violating the constitution. The courts that provide surveillance warrants should be brought into the open, he said.

"A secret court should not be interpreting the constitution," Snowden said. " We need public oversight."

One Twitter user asked Snowden what the average person could do to make their digital experience more secure. Snowden said using certain plug-ins with web browsers can enhance security, and services like TOR, an open source anonymity platform, are useful as well.

Those services work to a certain extent, Soghoian said, but most web browsers cannot do much to withstand attacks from hackers or agencies such as the NSA.

"If you're getting the service for free, the company is not going to be optimizing the experience with your best interest in mind," Soghoian said. "If you want a secure online service, you're going to have to pay for it."