What's the benefit? If you're intent on protecting your identity, why register at all? As you probably know from reading our blog, you get copyright protection automatically. You need the registrationtypically for three reasons: (1) if you want to sue someone; (2) it allows you to seek statutory damages and attorney fees if your registration is in place before the infringement occurs (or you register within 90 days of publication); and (3) registration provides a means for people to reach you in the event they want to license or exploit the work (or find you to sue you for infringement). In reality, we're willing to bet that 99% of registrants don't exercise these rights --- that is, they don't sue and the filing isn't necessary to locate them.
Ultimately, there's no secrecy anyway. No matter what lengths you go to preserve your identity, you'll have to (1) provide a mailing address for the certificate; and (2) more importantly, you'll have to identify yourself in court if you later want to preserve your rights and go after someone who rips you off. If you don't want to go after infringers and the sole reason for doing this is to make sure nobody knows who you are, then we're back to the question, why register at all?
Placing PGP data in one of the fields. Like we said, we're no tech geniuses, so, maybe we're not seeing the advantage of embedding the PGP key in one of the document fields. We're not clear what that gets you except to prove that the secret claimant and pseudonym are the same. Or is this like the DaVinci Code, and somebody is supposed to figure it all out later after you're gone (as religious or government operatives pursue each other)?
Bottom line dept. We support your desire to use a pseudonym. There's a great tradition for that in the U.S. But we don't think the Copyright Office will look fondly on placing improper information (embedded PGP keys) in an application field. After all, inserting an unrelated PGP key is not an answer to a question. Embedding it in the deposit materials seems a bit unhelpful and presumes that the Copyright Office will forever retain your materials (which it does not -- See Section 17 USC Sec. 704 (d)). We would recommend either not registering or perhaps pursuing rights under aCreative Commons license.