* {{Code|$type}} must be {{Code|symmetric}}.
* {{Code|$key}} is the secret key which is used for both encryption and decryption of input data. It must be a string or binary item. Its length is fixed and depends on the chosen algorithm: {{Code|8 bytes for DES}}, {{Code|16 bytes for AES}}.
* {{Code|$algorithm}} must either be {{Code|DES}} or {{Code|AES}}. Other algorithms are not supported so far, but, of course, can be added on demand. '''Default is {{Code|DES}}'''.
|-
| '''Errors'''