Useful GPG commands

Encryption/decryption commands

To encrypt a plaintext file with the recipient's public key:
```
  gpg -e -r recipient_userid textfile
```
To sign a plaintext file with your secret key:
```
  gpg -s textfile
```
To sign a plaintext file with your secret key and have the output readable to people without running GPG first:
```
  gpg --clearsign textfile
```
To sign a plaintext file with your secret key, and then encrypt it with the recipient's public key:
```
  gpg -se -r recipient_userid
```
To decrypt an encrypted file, or to check the signature integrity of a signed file:
```
  gpg [-o outputfile] ciphertextfile
```

To generate your own unique public/secret key pair:
```
  gpg --gen-key
```
To add a public or secret key file's contents to your public or secret key ring:
```
  gpg --import keyfile
```

To extract (copy) a key from your public or secret key ring:

  gpg -ao keyfile --export userid

  gpg -ao keyfile --export-secret-key

To view the contents of your public key ring:
```
  gpg --list-keys
```
To view the "fingerprint" of a public key, to help verify it over the telephone with its owner:
```
  gpg --fingerprint userid
```
To view the contents and check the certifying signatures of your public key ring:
```
  gpg --check-sigs
```
To edit a key:
```
  gpg --edit-key userid
```
To remove a key or just a userid from your public key ring:
```
  gpg --delete-key userid
```
To permanently revoke your own key, issuing a key compromise certificate:
```
  gpg --gen-revoke userid
```

To disable or re-enable a public key on your own public key ring:

  gpg --batch --edit-key userid disable

  gpg --batch -edit-key userid enable

To create a signature certificate that is detached from the document:
```
  gpg -sb textfile
```
To detach a signature certificate from a signed message
```
  gpg -b ciphertextfile
```

To produce a ciphertext file in ASCII format, just add the -a option when encrypting or signing a message or extracting a key:
```
  gpg -sea textfile
```
To specify a recipient, add the -r option followed by a user id:
```
  gpg -se -r recipient textfile
```
To specify an output file, add the -o option followed by a filename:
```
  gpg -d -o outputfile textfile
```