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2022-06-01 Wed
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Working with gpg

Notes on working with gpg, creating and editing keys, exporting and importing backups et.c.

gpg manual

The GNU Privacy Handbook

General tips

Commands

# list keys
gpg -k

# list private keys
gpg -K

Key output

pub   rsa2048 2019-03-04 [SC] [expires: 2023-03-03]
      XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
uid           [ unknown] Firstname Lastname <name@place.org>
sub   rsa2048 2019-03-04 [E] [expires: 2023-03-03]
  • the XXX.. is the keyid
    • it can be used as a name for the other commands
  • [ unknown] is the level of trust
  • if the key is expired it will be clear
  • the [SC] or [E] (or A) stuff are key flags denoting the usage

    • relevant snippen from the code: 

      /* Usage flags */
#define PUBKEY_USAGE_SIG     GCRY_PK_USAGE_SIGN  /* Good for signatures. */
#define PUBKEY_USAGE_ENC     GCRY_PK_USAGE_ENCR  /* Good for encryption. */
#define PUBKEY_USAGE_CERT    GCRY_PK_USAGE_CERT  /* Also good to certify keys.*/
#define PUBKEY_USAGE_AUTH    GCRY_PK_USAGE_AUTH  /* Good for authentication. */

Export gpg keys

  • the --armor options exports the keys in ascii
  • --export is for public keys while --export-secret-keys is for private
  • when exporting for backup one should tell gpg to do so --export-options export-backup

Import gpg keys

Just --import.

Also --pinentry-mode loopback is useful.

PoC of backup and restoration

Expand snippet... 
whoami
# laptop-me

# assume we already have generated a keypair
gpg --armor \
    --export-secret-keys \
    --export-options export-backup \
    --output backup \
    me@email # or keyid

sudo cp backup /home/server-me/backup
sudo chown server-me:server-me /home/server-me/backup

su - server-me

whoami
# server-me

gpg --pinentry-mode loopback \
    --import \
    backup