LJ Idol Presents:

Well, biometrics at its most basic is using something that you *are* (fingerprint, retinal patterns, voice pattern, etc.) to prove to a system that you are who you say you are. So it's not so much that biometrics do anything in and of itself, save granting access to a system. It just sounds cooler than saying, "I used their Gmail password to intercept the e-mail!"

That said, if you spoofed someone's biometrics (or went full-on Demolition Man and brought their eyeballs with you), you could get access to what they would normally have access. So you could go straight to their Gmail or Tor "Sent" folder and see what they'd sent. (Not quite the same as "intercept.")

(Or, if you want to do it the hard way, break into some network admin's onion router using their biometric data, turn on any sniffing capability the router might have, and then wait to see if it's susceptible to a timing attack. But you'd need to do that well in advance of the e-mail being sent, and you'd have to filter out the e-mails you had no interest in.)

So, short answer: I think they hand-waved a bit there, because the biometrics aren't the interesting part.