Java Requires Chilkat v11.0.0+

RSA Sign with PKCS8 Encrypted Key

See more RSA Examples

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it). Chilkat2 Java

import com.chilkatsoft.chilkat2.Cert;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.PrivateKey;
import com.chilkatsoft.chilkat2.PublicKey;
import com.chilkatsoft.chilkat2.Rsa;

public class ChilkatExample {

    public static void main(String[] args) {
        // This example assumes the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        PrivateKey privKey = new PrivateKey();

        // Load the private key from an RSA PEM file:
        try {
            privKey.loadAnyFormatFile("raul_privateKey.key", "a0123456789");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        Rsa rsa = new Rsa();

        // Import the private key into the RSA component:
        try {
            rsa.usePrivateKey(privKey);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // This example will sign a string, and receive the signature
        // in a hex-encoded string.  Therefore, set the encoding mode
        // to "hex":
        rsa.setEncodingMode("hex");

        String strData = "This is the string to be signed.";

        // Sign the string using the sha256 hash algorithm.
        // Other valid choices are sha1, sha384, sha512 and others.
        String hexSig;
        try {
            hexSig = rsa.signStringENC(strData, "sha256");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println(hexSig);

        // Now verify with the public key.
        // This example shows how to use the public key from
        // a digital certificate (.cer file)
        Cert cert = new Cert();
        try {
            cert.loadFromFile("raul_publicKey.cer");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        PublicKey pubKey = new PublicKey();
        cert.getPublicKey(pubKey);

        Rsa rsa2 = new Rsa();
        try {
            rsa2.usePublicKey(pubKey);

            // Verify the signature against the original data:
            rsa2.setEncodingMode("hex");
            rsa2.verifyStringENC(strData, "sha256", hexSig);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("Signature verified!");

        // Verify with incorrect data:
        try {
            rsa2.verifyStringENC("something else", "sha256", hexSig);
            System.out.println("Hmmm... that's not right...");
        } catch (ChilkatException e) {
            System.out.println("Signature not verified! (which was expected in this case)");
        }
    }
}