Getting Errors on paypal Website Payments Standard ( Java API)

I am new to the paypal api system, I am integrating payment gateway on my web application using java/servlet api, i have gone through this link https://cms.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=developer/library_download_sdks in that i have downloaded "Website Payments Standard" java.zip file from there i am executing the sample i am getting the error as 开发者_开发百科"Illegal key size", kindly help me out in solving this one, And how to get the private keypassword in sandbox environment, i have created sandbox account.