Xác minh chữ ký Digital cho các tệp Xls

        
// Set up input Xls file
String filePath = "input.xls";

// Instantiate Signature for input file
Signature signature = new Signature(filePath);

//Provide verification options
DigitalVerifyOptions options = new DigitalVerifyOptions();

// Digital signature comment
options.setComments("Approved");

// specify period of signatures
options.setSignDateTimeFrom(new Date(2020, 12, 12));
options.setSignDateTimeTo(new Date(2022, 12, 12));
                    
// Verify document signatures
VerificationResult result = signature.verify(options);

//process result
if (result.isValid())
{
    //..
}