Java

Verify Opaque Signature and Retrieve Signing Certificates

See more Digital Signatures Examples

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    boolean success = false;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkCrypt2 crypt = new CkCrypt2();

    // Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
    success = crypt.VerifyP7M("qa_data/p7m/opaqueSig.p7","qa_output/originalData.dat");
    if (success == false) {
        System.out.println(crypt.lastErrorText());
        return;
        }

    // Alternatively, we can do it in memory...
    CkBinData binData = new CkBinData();
    success = binData.LoadFile("qa_data/p7m/opaqueSig.p7");
    // Your app should check for success, but we'll skip the check for brevity..

    // If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
    success = crypt.OpaqueVerifyBd(binData);
    if (success == false) {
        System.out.println(crypt.lastErrorText());
        return;
        }

    // For our testing, we signed some text, so we can get it from the binData..
    System.out.println("Original Data:");
    System.out.println(binData.getString("utf-8"));

    // After any method call that verifies a signature, the crypt object will contain the certificate(s)
    // that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

    // Get each signing certificate, and build the certificate chain for each.
    CkCert cert = new CkCert();
    CkCertChain certChain = new CkCertChain();
    int numCerts = crypt.get_NumSignerCerts();
    int i = 0;
    while (i < numCerts) {
        crypt.LastSignerCert(i,cert);
        System.out.println(cert.subjectDN());

        success = cert.BuildCertChain(certChain);
        if (success == false) {
            System.out.println(cert.lastErrorText());
            return;
            }

        i = i+1;
        }
  }
}