verify signature without need to original message (in java)

Question

I want to sign a message and then I get the original message from the signature. I find RSA & DSA signature in java: http://docs.oracle.com/javase/tutorial/security/apisign/vstep4.html
but their verify method use original data for verify and can not recover message from signature.
Is there any way to do it in Java or any free-library for Java?
thanks all.

Answer 1

You can use BouncyCastle. It supports ISO-9796-2. And ISO9796Test.java provides an example. Here is an excerpt that might help:

RSAKeyParameters pubParameters = new RSAKeyParameters(false, mod3, pub3);
RSAKeyParameters privParameters = new RSAKeyParameters(true, mod3, pri3);
RSAEngine rsa = new RSAEngine();
byte[] data;
ISO9796d2Signer eng = new ISO9796d2Signer(rsa, new RIPEMD128Digest());
eng.init(true, privParameters);
eng.update(msg4[0]);
eng.update(msg4, 1, msg4.length - 1);
data = eng.generateSignature();
eng.init(false, pubParameters);
eng.update(msg4[0]);
eng.update(msg4, 1, msg4.length - 1);
if (eng.hasFullMessage()) {
    eng = new ISO9796d2Signer(rsa, new RIPEMD128Digest());
    eng.init(false, pubParameters);
    if (!eng.verifySignature(sig4)) {
        // signature tampered with
    }
    byte[] message = eng.getRecoveredMessage(), 0, msg4);
}