Bruce Schneier über den Nutzen von E-Mail Verschlüsselung im Licht von PRISM.
Leaving aside the fact that much of what the NSA is collecting can’t be encrypted by the user — telephone metadata, e-mail headers, phone calling records, e-mail you’re reading from a phone or tablet or cloud provider, anything you post on Facebook — it’s hard to give good advice.
The NSA has to process a ginormous amount of traffic. It’s the “drinking from a fire hose” problem; they cannot afford to devote a lot of time to decrypting everything, because they simply don’t have the computing resources. There’s just too much data to collect. In these situations, even a modest level of encryption is enough — until you are specifically targeted. This is why the NSA saves all encrypted data it encounters; it might want to devote cryptanalysis resources to it at some later time.