When developing a new application, it's often necessary to generate a secret key for encoding and decoding tokens. This can be easily achieved via the openssl toolkit.

openssl rand -base64 32 | tr -d '\n'

Here's a more in depth explanation of the command:

• openssl: This is the CLI for using the OpenSSL toolkit, which is installed by default on most Linux distributions.
• -base64: This option tells to the rand subcommand to encode the output in base64.
• 32: This is the number of bytes to generate. Since each base64 character represents 6 bits of the original data, 32 bytes will generate a 256-bit key.
• tr: This command is used to delete characters. In this particular case is used to delete any newline that may be included in the output form OpenSSL