I have used the same smart card on multiple machines with Windows 7 and JSignPdf 1.3.9 and works fine. The same card on Windows XP (Professional, Service Pack 3, Version 2002, 32bit) fails with the exception below. The card works on those machines as I can sign Word docs with no problem. I am using a non-visible signature without any timestamping. Both Windows 7 and XP machines have the same proxy settings in Windows. Any ideas? We had planned to recommend JSignPdf as an option to roll out signed PDFs to some thousands of users but we're now stuck with this one as a big proportion of these users still have Windows XP.

INFO  Starting JSignPdf
INFO  Checking input and output PDF paths.
INFO  Loading private key
INFO  Getting certificate chain
INFO  Opening input PDF file: <filename>.pdf
INFO  Creating output PDF file: <filename>_signed.pdf
INFO  Creating signature
INFO  Setting certification level
INFO  Processing (it may take a while) …
ERROR Problem occured
ExceptionConverter: java.security.SignatureException: Ï ôýðïò ðïõ êáèïñßóôçêå äåí åßíáé Ýãêõñïò.

at sun.security.mscapi.RSASignature.signHash(Native Method)
at sun.security.mscapi.RSASignature.engineSign(RSASignature.java:390)
at java.security.Signature$Delegate.engineSign(Unknown Source)
at java.security.Signature.sign(Unknown Source)
at com.lowagie.text.pdf.PdfPKCS7.getEncodedPKCS7(Unknown Source)
at net.sf.jsignpdf.SignerLogic.signFile(SignerLogic.java:365)
at net.sf.jsignpdf.SignerLogic.run(SignerLogic.java:108)
at java.lang.Thread.run(Unknown Source)
INFO  Finished: Creating of signature failed.