The problem with GPG is the chicken-and-egg situation, along with user apathy. I literally don't know anyone I regularly email who uses it, so I can't use it either. Then there's the fact that virtually no email client supports it by default. If email providers like google actively supported and promoted it and provided public key management in the contact list along with a browser plugin for the private key management and actual encryption/decryption, we might even stand a chance of it happening, but google of all people will never directly support it as it'll prevent their full text search from working. (I'm aware of FireGPG - changes to GMail typically break it, so you can't rely on it)
I digitally signed all my outgoing email for a while, which did get some people asking why they couldn't read the attachment, (the signature is an ascii file but fairly useless to a human reader) but explaining email encryption and signing didn't cause any uptake ("nobody is interested in my email", "I have nothing to hide") so I gave up. I do still digitally sign important correspondance such as invoices and payment reminders.
I agree, it is difficult, but my close friends and important correspondents do use email encryption (as per my request) for sensitive topics.
I won't put anything sensitive in an email unless it is encrypted; that is generally the way a I break my friend's apathy to using it. It doesn't necessarily work, however, for corporations &c...
Anytime I have a feeling I will be discussing sensitive materials with someone, I start signing my messages so they know I am good to go. If they don't know what it is, I take the opportunity to introduce security.
I understand the technology- but my qualms is with the process and the time-lines mentioned with regards to the interception. Why cannot the sanction process be 24 x 7? Also, why should a sanction of such a critical action like reading someone's email go unreviewed for two months?
We are in 2009 and not in 1984, right?
I feel this has misuse written all over it. And unfortunately, I feel GPG is not really the answer here for 99% of the email users (unless gmail and yahoo decide to turn it on by default).
This sounds like a great project for a YC startup: make email secure for everyone, and make it as easy to use as DropBox. It sounds mundane, by I think the comments so far are accurate; no one uses GPG, etc., because it's too difficult for non-techies to use. I've tried using several things over the years (even HushMail), but since my colleagues and friends wouldn't, I ended up giving up. I wish I had the chops to create such a thing (I'm a web designer, so wrong side of the brain). I'm sure there's someone reading Hacker News who could solve the problem.
Done right I support the idea of getting access to the correspondence of individuals - however so far I disagree with pretty much every practical implementation.
Interception leaves a particularly bad taste for me. I've seen it done once; as it happens for the right reasons and with a positive result. It still left me feeling a bit crap because of how it was done (with only the vague vestiges of a warrant).
On the other hand I would have no compunction about breaking into the email account of an individual if the need arose (i.e. requiring correspondence to prove or stop a crime).Ironically doing so is a) technically reasonably easy (especially if you have their computer) and b) legally next to impossible to do - usually you have to use RIPA and go to the ISP... (aka months, though I dont deal with that area of stuff so Im not sure). So it's where you draw the line morally and ethically.
Intercepting every mail is clearly a massive infringement of our privacy rights. Intercepting an individuals correspondence where there is a serious degree (not just a reasonable one) of suspicion to warrant the action I can agree with - but as yet there appears no realistic mechanism to do this without creating an easily subverted system which can be used wrongly.
Also encrypt your hard drive, preferably with hardware encryption that requires a physical key.
Not fool proof, but it is likely to deter the vast majority of invasive attempts.