(Java) Convert Java KeyStore to PKCS12 / PFX

Loads a Java keystore file and saves it as a PKCS12 / PFX. A Java keystore (JKS) can contain two types of entries: (1) trusted root certificates or (2) private keys + cert chains. Usually a JKS will contain all entries of one type or another (and thus a particular JKS serves one purpose or another; meaning that a JKS containing trusted roots is used as a source for verifying pre-trusted roots, and a JKS containing private keys (and cert chains) is used as a secure, encrypted store for private keys).

A PKCS12 / PFX typically contains one or more private keys, along with each private key's certificate chain. Therefore, it typically makes sense to only write the private key entries to a PKCS12 (and the associated certificate chains). If a JKS contains trusted root certificates, it makes more sense to conver it to a PEM file (such as the CA cert bundle in PEM format from mozilla.org).

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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[])
  {
    // This requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkJavaKeyStore jks = new CkJavaKeyStore();

    String jksPassword = "myJksPassword";

    // Load the Java keystore from a file.  The JKS file password is used
    // to verify the keyed digest that is found at the very end of the keystore.
    // It verifies that the keystore has not been modified.
    boolean success = jks.LoadFile(jksPassword,"/someDir/keyStore.jks");
    if (success != true) {
        System.out.println(jks.lastErrorText());
        return;
        }

    // To convert, we'll access the private key entries
    // from the JKS, add each to the PKCS12, and then save the PKCS12.
    CkPfx pkcs12 = new CkPfx();

    int numPrivateKeys = jks.get_NumPrivateKeys();
    int i;

    CkPrivateKey privKey;
    CkCertChain certChain;

    // For each private key entry, get the private key and
    // the associated certificate chain.
    // Each private key is password protected.  Usually it is the same
    // password as used for the keyed digest of the entire JKS.  
    // However, this does not have to be.  The password is passed
    // here to handle the possibility of each private key requiring
    // a different password.
    i = 0;
    while (i < numPrivateKeys) {
        privKey = jks.GetPrivateKey(jksPassword,i);
        System.out.println(jks.getPrivateKeyAlias(i));
        certChain = jks.GetCertChain(i);

        // Add the private key and it's associated certificate chain to the PKCS12.
        success = pkcs12.AddPrivateKey(privKey,certChain);
        if (success != true) {
            System.out.println(pkcs12.lastErrorText());

            return;
            }

        i = i+1;
        }

    // Save the PKCS12 / PFX to a file.
    // The password can be the same as the JKS password, or something new.
    // (With the PKCS12 format, there is a single password for the entire contents
    // of the file.  With the JKS format, there is flexibility in allowing each private key
    // to have it's own password.)
    String pkcs12Password = "myNewPassword";
    success = pkcs12.ToFile(pkcs12Password,"/pkcs12_files/myPfx.p12");
    if (success != true) {
        System.out.println(pkcs12.lastErrorText());
        }
    else {
        System.out.println("Successfully saved to PKCS12 format.");
        }
  }
}