The revelations of Edward Snowden about the NSA's snooping of citizens both inside and outside the US are posing more questions than they answer at the moment. One key area is whether the use of encryption -- for example for email -- is effective against the techniques and raw power available to the NSA (and equivalents in other countries). That's something that has come up before in the context of the UK's Snooper's Charter. When a top official there was asked whether the proposed surveillance technology would be able to cope with encrypted streams, he replied: "it will." Snowden's claims about massive, global spying makes the issue even more pertinent.