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Lets say I add an expiration date to a GPG/PGP key, then for some reason am unable to extend the expiration date of the key before its time is up.

Assuming I still have access to the private key (and the public key has only expired, not been revoked) can I still renew it?

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  • Note: This would be quick and easy to test by simply creating a new key that expires in five minutes. However, I'm looking for answers such as "Yes, you can renew it in GPG, but some PGP clients will throw errors." or "No, if key's don't have an updated version when they expire, GPG will stop checking if a newer version is available on the keyserver." or "It's bad practice, create a new key pair instead."
    – IQAndreas
    Sep 18, 2014 at 10:29
  • Yes; I see no reason it wouldn't be possible. SSL Certificates expire all the time, and are renewed after they had expired, furthermore just because the certificate expired does not mean the certificate can no longer used.
    – Ramhound
    Sep 18, 2014 at 10:48
  • 1
    It's important to state that setting an expiration date for your key is no protection against it being compromised. A malicious attacker could, if he gets hold of your private key, still prolong the validity of the key. Therefore having a revocation certificate is still heavily recommended.
    – David
    Dec 2, 2016 at 13:56

2 Answers 2

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117

Yes, you can renew it at any time. Here's how to do it:

gpg --list-keys
gpg --edit-key (key id)

Now you're in the gpg console. (By default, you're working on the primary key.) If you need to update a sub-key:

gpg> key 1

Now you can set the expiration for the selected key:

gpg> expire
(follow prompts)
gpg> save

Now that you've updated your key, you can send it out:

gpg --keyserver pgp.mit.edu --send-keys (key id)

And, yes, having an expiration date for your keys is a very good idea. You should never really have a key with no expiration date. If it's compromised, it could be used forever.

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  • 6
    If it's compromised and the attacker renew the expiration, how?
    – fikr4n
    Sep 27, 2017 at 13:06
  • @BornToCode, I can guess that in this case the real key owner has to revoke the key... game over for a hacker...
    – Drew
    May 2, 2018 at 5:34
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According OpenPGP Best Practices on Riseup.net (archived)1, yes, it is possible, and there don't seem to be any recommendations against it:

People think that they don’t want their keys to expire, but you actually do. Why? Because you can always extend your expiration date, even after it has expired! This “expiration” is actually more of a safety valve or “dead-man switch” that will automatically trigger at some point. If you have access to the secret key material, you can untrigger it. The point is to setup something to disable your key in case you lose access to it (and have no revocation certificate).

[1]: The link now points to an Internet Archive entry as the original one is dead.

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