Java

Create and Verify an Opaque PKCS7/CMS Signature

See more Digital Signatures Examples

Demonstrates how to create a PKCS7 opaque signature, and also how to verify an opaque signature. An opaque signature is different than a detached PKCS7 signature in that it contains the original data. Verifying an opaque signature retrieves the original content. Chilkat2 Java

import com.chilkatsoft.chilkat2.Cert;
import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Crypt2;
import com.chilkatsoft.chilkat2.PrivateKey;

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.

        Crypt2 crypt = new Crypt2();

        // A certificate and private key is needed to create a signature.
        // Chilkat provides many different ways to load a certificate and private key, such
        // as from a PFX/.p12, Java keystore, JWK, Windows registry-based certificate stores, and other sources.
        // This example will load the certificate from a .crt and the private key from a .key file

        Cert cert = new Cert();
        // The LoadFromFile method will automatically detect the format and load it.
        try {
            cert.loadFromFile("qa_data/certs/test_12345678a.cer");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Our private key is in an encrypted PKCS8 format.
        // If you don't know the format of your key, but you do know it's encrypted,
        // and requires a password, then just call any of the Chilkat methods that load
        // a private key w/ a password argument.  Chilkat will auto-detect the format
        // and load it correctly even if it's not the format indicated by the method name..
        PrivateKey privKey = new PrivateKey();
        String password = "12345678a";
        try {
            privKey.loadPkcs8EncryptedFile("qa_data/certs/test_12345678a.key", password);

            // Set properties required for signing.

            // Tell it to use the cert and private key we've loaded.
            crypt.setSigningCert2(cert, privKey);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Indicate we want the opaque signature in base64 format:
        crypt.setEncodingMode("base64");

        // Sign the string using the "utf-8" byte representation:
        crypt.setCharset("utf-8");

        // Create the opaque signature:
        String originalData = "This is the string to be signed.";
        String opaqueSig;
        try {
            opaqueSig = crypt.opaqueSignStringENC(originalData);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println(opaqueSig);

        // The output looks like this:
        // MIIPgQYJKoZIhvcNAQcCoIIPcjCCD24CAQExCzAJBgUrDgMCGgUAMC8GCSqGSIb3DQEHAaAiBCBUaGlzIGlzIHRoZSBzdHJpbmcgdG8gYmUgc...

        // ----------------------------------------------------------------------------------------------
        // Now let's verify the signature and retrieve the original data.
        // We'll use a new Crypt2 object to keep things completely separate...

        Crypt2 vCrypt = new Crypt2();

        vCrypt.setEncodingMode("base64");
        vCrypt.setCharset("utf-8");

        String extractedData;
        try {
            extractedData = vCrypt.opaqueVerifyStringENC(opaqueSig);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        System.out.println("The extracted data: " + extractedData);

        // The output is:
        // The extracted data: This is the string to be signed.
    }
}