"Every journalist should assume that there is no such thing as confidential digital communication," Rusbridger told delegates at the Polis conference today.
He said most news outlets "don't even begin to deal with [the issue on online security]". The encryption process is "not impossible", he said, "but it’s difficult for most journalists and it’s a bit time consuming.
"And most journalists don’t do it. But we’re all going to have to wake up to this world in which people can intercept anything".
Articles from Journalism.co.uk on online security:
Computer security: how to avoid being hacked
How journalists can enter the 'deep web' to stay secure
Online security advice for journalists (podcast)
On the Edward Snowdon leaks
Rusbridger was asked whether the Guardian's reporting on the leaked documents from Edward Snowden had "damaged national security", to which the editor-in-chief said: "I see no evidence".
He added that most of the accusations were "general", while other more particular allegations were "nonsense".
But he added he had "thought about it a lot", and that the Guardian "realised the seriousness of what we were writing about".
He also highlighted the need for "a debate about the laws" surrounding this issue, explaining that the situation is currently based on "analogue laws stretched to breaking point to deal with the digital situation".
When asked about the response from other media outlets, following the Guardian's reporting, he said "the media around the world thought this was an exceptionally significant story and covered it obsessively.
"There were one or two papers here that didn’t.
On the impact of BuzzFeed
Moving to the rise of other digital outlets, Rusbridger was asked whether the Guardian can compete with the likes of BuzzFeed.
Rusbridger said it could, adding that while it BuzzFeed is "very smart at what it does", it is also "only about 3 minutes old".
There is demand for content across a spectrum of styles, from long-form to lists, videos to interactives, he added.
On sponsored content
Rusbridger was also asked about whether the Guardian's use of sponsored content signalled any risk to its editorial independence, but he said no one has flagged up any issues.
"I think the test is whether anyone can find anything that's changed in our journalism, and nobody yet has," he said.
He added that recently reported figures of £70 million in digital revenue, shows a "broadly positive story", but added there are "dangers in all forms of funding".