• Generate a random password:

    $ openssl rand -base64 18

  • Examine ASN.1 structure of a CSR:

    $ openssl asn1parse -i -in ./0000_csr-certbot.pem

  • Generate a key (interactive mode):

    $ gpg --gen-key

  • You can use the key generator in an unattended mode. Values in the example below are the same as the defaults proposed in the interactive mode above. Parameters in comments are there for reference:

    $ gpg --gen-key --batch <<EOF
  Key-Type: RSA
  Key-Length: 2048
  Subkey-Type: RSA
  Subkey-Length: 2048
  Expire-Date: 0
  Name-Real: Kevin
  # Name-Email: [email protected]
  # Name-Comment: My auto-generated key
  # Passphrase: my_secret_passphrase
  EOF

  • List available keys for the current user:

    $ gpg --list-keys

  • Decrypt a file:

    $ gpg --decrypt archive.001.tar.gpg --output archive.001.tar

  • Same as above but for a collection of files:

    $ gpg --multifile --decrypt archive.*.tar.gpg