passphrases that you can memorize - but that even the nsa can't guess.
It’s getting easier to secure your digital privacy. iPhones now encrypt a great deal of personal information; hard drives on Mac and Windows 8.1 computers are now automatically locked down; even Facebook, which made a fortune on open sharing, is providing end-to-end encryption in the chat tool WhatsApp. But none of this technology offers as much protection as you may think if you don’t know how to come up with a good passphrase.
A passphrase is like a password, but longer and more secure. In essence, it’s an encryption key that you memorize. Once you start caring more deeply about your privacy and improving your computer security habits, one of the first roadblocks you’ll run into is having to create a passphrase. You can’t secure much without one.
For example, when you encrypt your hard drive, a USB stick, or a document on your computer, the disk encryption is often only as strong as your passphrase. If you use a password database, or the password-saving feature in your web browser, you’ll want to set a strong master passphrase to protect them. If you want to encrypt your email with PGP, you protect your private key with a passphrase. In his first email to Laura Poitras, Edward Snowden wrote, “Please confirm that no one has ever had a copy of your private key and that it uses a strong passphrase. Assume your adversary is capable of one trillion guesses per second.”