Problems using subkeys for encryption and signing

Mohak Shah's Avatar

Mohak Shah

04 Sep, 2017 12:09 AM

Which of our tools is giving you problems? GPG Keychain, GPGMail

Describe your problem. Add as much detail as possible. I recently created a new gpg keypair. Following the advice on https://wiki.debian.org/Subkeys and several other places, I decided to keep my master key offline on a seperate device, copying just the subkeys on my mac for encryption and signing. So, my mac only has the public portion of the master key and public+private subkeys. Unfortunately, GPG Keychain and GPGMail do not recognise the private subways and treat all the subkeys as just public keys. GPG Keychain lists the key with "Type" as 'pub' and GPGMail says "Secret key is missing" when I open an encrypted email. I have also checked by using GNUPG on the command-line; both signing and encryption work quite well there.

For reference, here's the output of gpg --list-secret-keys:

sec#  rsa4096/0xMASTERKEYID 2017-09-03 [SC]
      ----------KEYGRIP-------------
uid                   [ultimate] Mohak Shah <[email blocked]>
ssb   rsa4096/0xSUBKEYID 2017-09-03 [S] [expires: 2022-09-02]
ssb   rsa4096/0xSUBKEYID 2017-09-03 [E] [expires: 2022-09-02]

Are you using any other Mail.app plugins? No

  1. Support Staff 1 Posted by Mento on 12 Sep, 2017 12:42 PM

    Mento's Avatar

    Hi Mohak,

    please try this (if you didn't already):
    1. Delete the secret keys from your mac.
    2. Export your secret keys again from your offline device: gpg -a --export-secret-subkeys 0xMASTERKEYID > secsubs.asc
    3. Import secsubs.asc on your mac.

    Regards, Mento

  2. 2 Posted by Mohak Shah on 12 Sep, 2017 11:32 PM

    Mohak Shah's Avatar

    That worked! I believe the problem was that I had originally imported the subkeys using gpg 2.1 which uses a different store for private keys than gpg 2.0, the version GPGTools use. Anyway, thanks for your help!

    P.S.: I hope you guys will move to gpg 2.1 soon. As you might already know, 2.0 is going to reach EOL this december.

  3. Support Staff 3 Posted by Steve on 13 Sep, 2017 08:11 AM

    Steve's Avatar

    Thanks for the feedback and great news this indeed solved your problem.

    gpg 2.2 is already integrated in the nightly build and will be included in the upcoming next beta release.

    I'm closing this discussion. Should you need further assistance or have questions you can re-open this discussion here or open a new one any time.

    Best, steve

  4. Steve closed this discussion on 13 Sep, 2017 08:11 AM.

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