Basics
Exporting keys
gpg -o key.gpg --export <KEY ID>
Export key in ASCII:
gpg -o key.asc --armor --export <KEY ID>
Note: Omitting the -o|--output option will print the key to stdout.
Importing keys
gpg --import key.gpg
gpg --import key.asc
Only merge updates for keys already in key-ring:
gpg --import key.asc --import-options merge-only
Managing your keyring
Generate a new key:
gpg --gen-key
# or, generate a new key with dialogs for all options
gpg --full-gen-key
List public keys:
gpg -k
gpg --list-keys
List secret keys:
gpg -K
gpg --list-secret-keys
Using a keyserver
Import keys from keyserver:
gpg --receive-keys <KEY IDS>
Upload keys to keyserver:
gpg --send-keys <KEY IDS>
Request updates from keyserver for keys already in your keyring:
gpg --refresh-keys
Search keys from keyserver:
gpg --search-keys "<SEARCH STRING>"
Override keyserver from ~/.gnupg/gpg.conf
gpg --keyserver <URL> ...
Trusting a key
gpg --edit-key <KEY ID>
# In the interactive prompt:
gpg> trust
gpg> save
NOTE: You can use the owner’s email or name (or part thereof) instead of the key ID for --edit-key
Encrypting
Public key encryption
This will produce an encrypted file, secret.txt.gpg, that can only be decrypted by the recipient:
gpg -e -o secret.txt.gpg -r <RECIPIENT> secret.txt
For <RECIPIENT> you can use their key ID, their email, or their name (or part thereof).
gpg -e -r <KEY ID> ...
gpg -e -r "Bez" ...
gpg -e -r "bezalelhermoso@gmail.com" ...
Specifying multiple recipients
gpg -e -r <RECIPIENT> -r <ANOTHER RECIPIENT> ... secret.txt
NOTE: Omitting -o|--output will produce an encrypted file named <ORIGINAL FILENAME>.gpg by default.
Symmetric encryption
Encrypt file using a shared key. You will be prompted for a passphrase.
gpg --symmetric secret.txt
# or
gpg -c secret.txt
Decrypting
Decrypting a file
gpg -d -o secret.txt secret.txt.gpg
If the file is encrypted via symmetric encryption, you will be prompted for the passphrase.
NOTE: Omitting -o|--output will print the unencrypted contents to stdout
Signing & Verifying
Signing
gpg -o signed-file.txt.gpg -s file.txt
This can be used during encryption to also sign encrypted files:
gpg -s -o secret.txt.gpg \
-r <RECIPIENT> secret.txt
Verifying a signature
gpg --verify file.txt.gpg
Viewing content of signed file
gpg -d signed-file.txt.gpg
Miscellaneous
Components
List all components:
gpgconf --list-components
Kill a component:
gpgconf --kill <COMPONENT> # i.e. gpgconf --kill dirmngr
Kill all components:
gpgconf --kill all
Parsing keyring data
Use --with-colons to produce an output that can easily be parsed i.e. with awk, grep. Fields are colon-separated.
gpg -k --with-colons
Field Quick Reference:
| Field # | Description |
| 1 | Record type |
| 2 | Validity |
| 3 | Key length in bits |
| 4 | Public key algorithm |
| 5 | Key ID |
| 6 | Creation date |
| 7 | Expiry date |
| 8 | Certificate S/N, UID hash, trust signature info |
| 9 | Ownertrust |
| 10 | User ID |
| 11 | Signature class |
| 12 | Key capabilities |
| 13 | Issuer fingerprint |
| 14 | Flag field |
| 15 | S/N of token |
| 16 | Hash algorithm |
| 17 | Curve name |
| 18 | Compliance flags |
| 19 | Last update timestamp |
| 20 | Origin |
See GnuPG Details for more details.
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