I am new to GnuPG. I have generated a key in with Enigmail in Thunderbird so far, which is also available through Seahorse now.
- I generated a key with 2048bit. However, I read that 4096 is now recommended for some purposes. Since my key is not distributed yet, I can generated a new one at any time. Should I generate one with 4096bit? Are there any disadvantages? Incompatibilities?
- I noticed that I can add multiple email-addresses to one key. Is this advised? I assume this might be a privacy problem if I do not want to have my business and private email-addresses linked.
- I have a smartcard which has a signature subkey, encryption subkey, authentication subkey. What is a subkey? How does the smartcard interact with GnuPG? Is there a key pre-installed on the card? How can I be sure that this key exists only once? Can I derive a key from the card so that I can read my emails also on computers where I do not have a card reader? What happens if the card breaks/gets lost? Can I make a backup of the keys on the card?
- Can I use my PGP-key to encrypt my home directory? Would this make sense?