How to Sign your Button Form Correctly

The signature parameter contains the calculated signature. The SignatureVersion and SignatureMethod parameters describe the characteristics of the signature you plan to provide. All three parameters must be present in your button form for it to be correctly signed.

To add your signature to the form

Paste your calculated signature into the value attribute that corresponds to the signature. To create a signature, see How to Generate a Signature.
Paste the name of your signing algorithm in the value attribute that corresponds to the signatureMethod, either HmacSHA256 or HmacSHA1.
Paste your signing version number into the value attribute that corresponds to the signatureVersion field. This value must be 2.

The signature portion of the button should be similar to the following:

  <input type="hidden" 
               name="signature" 
               value="rtnUZPP50DxgzmYOcUaFBvbhLqY=" >
              <input type="hidden" name="signatureVersion"
               value="2" >
              <input type="hidden" name="signatureMethod"
               value="HmacSHA256" >

For information on the high-level process for creating a button, see Creating Button Forms Dynamically .