Java security - MSCAPI provider: How to use without password popup?

Question

I've managed to use Sun's MSCAPI provider in my application. The problem I'm having now is that it always pops up a window, asking for a password, even though I've provided it in the code. This is a problem, because I need the cryptography functionality in a webservice.

Here's the code I have now:

String alias = "Alias to my PK";
char[] pass = "MyPassword".toCharArray();

KeyStore ks = KeyStore.getInstance("Windows-MY");
ks.load(null, pass);
Provider p =  ks.getProvider();

Signature sig = Signature.getInstance("SHA1withRSA",p);
PrivateKey key = (PrivateKey) ks.getKey(alias, pass)

sig.initSign(key);
sig.update("Testing".getBytes());
sig.sign();

This is working great, but I get a popup asking for the password when the last line is run. How do I prevent that?

Answer 1

The MSCAPI provider does not support providing the password to CAPI:

A compatibility mode is supported for applications that assume a password must be supplied. It permits (but ignores) a non-null password. The mode is enabled by default. (1)

To set the password through CAPI, you must call CryptSetKeyParam with the undocumented KP_KEYEXCHANGE_PIN or KP_SIGNATURE_PIN and hope your underlying hardware token provider supports it. (They are not completely undocumented - the documentation for Windows CE and Windows Mobile mention them (2) and they are included in the header files).