createSignedData()
createSignedData(string  $plainData) : \CryptoManana\DataStructures\SignedData
                        Creates a signed data object for the given input data.
Parameters
| string | $plainData | The plain input string. | 
Throws
- \Exception
- Validation errors. 
Returns
\CryptoManana\DataStructures\SignedData —The signed data object.