Translations:Concepts/OpenPGP Getting Started/14/en

Most OpenPGP keys have at least one subkey (all have exactly one main key). You usually need not care about this difference; your application (or rather the base application, usually GnuPG) selects the right one automatically. The main key is the one which the key fingerprint refers to and only the main key can certify: your own subkeys and user IDs and the user IDs of other keys. The subkeys can do everything else (mainly decryption and signing) if you configure them so. The reason the difference between these key types is mentioned here is that this is very important for key generation: You can separate the secret main key from the secret subkeys (with GnuPG; this is not part of the OpenPGP standard!). The subkeys can be replaced later, the main key cannot (that would be a new key not just a modified key). Thus if you create an offline main key at key generation which you protect by a very hard passphrase, store at least the passphrase securely and use the main key (and its passphrase) in secure environments only then you can keep this key "forever" (say 20 years). This is important for everyday keys. High security keys don't really need this separation (usually don't need subkeys at all). You should create one subkey for each capability you need: encryption, signing, and maybe authentication (for SSH).