Check validity of password to decrypt document

To check if a user password is valid for a standard encryption handler you need to set TElOfficeOpenXMLStandardEncryptionHandler.Password property and call IsPasswordValid() method of the handler.

To check if a user password is valid for agile encryption handler you need to use KeyEncryptorCount and KeyEncryptors[] properties of TElOfficeOpenXMLAgileEncryptionHandler class to get TElOfficeOpenXMLPasswordKeyEncryptor object, then set its Password property and call IsPasswordValid() method to check the password.