http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5 to JDK 1.8.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.asn1.test;

import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.util.encoders.Base64;
import org.bouncycastle.util.test.SimpleTest;

public class PrivateKeyInfoTest
    extends SimpleTest
{
    private static final byte[] priv = Base64.decode(
        "MC4CAQAwBQYDK2VwBCIEINTuctv5E1hK1bbY8fdp+K06/nwoy/HU++CXqI9EdVhC");

    private static final byte[] privWithPub = Base64.decode(
        "MHICAQEwBQYDK2VwBCIEINTuctv5E1hK1bbY8fdp+K06/nwoy/HU++CXqI9EdVhC" +
            "oB8wHQYKKoZIhvcNAQkJFDEPDA1DdXJkbGUgQ2hhaXJzgSEAGb9ECWmEzf6FQbrB" +
            "Z9w7lshQhqowtrbLDFw4rXAxZuE=");


    public String getName()
    {
        return "PrivateKeyInfoTest";
    }

    public void performTest()
        throws Exception
    {
        PrivateKeyInfo privInfo1 = PrivateKeyInfo.getInstance(priv);

        isTrue(!privInfo1.hasPublicKey());

        PrivateKeyInfo privInfo2 = new PrivateKeyInfo(privInfo1.getPrivateKeyAlgorithm(), privInfo1.parsePrivateKey());

        isTrue("enc 1 failed", areEqual(priv, privInfo2.getEncoded()));

        privInfo1 = PrivateKeyInfo.getInstance(privWithPub);

        isTrue(privInfo1.hasPublicKey());

        privInfo2 = new PrivateKeyInfo(privInfo1.getPrivateKeyAlgorithm(), privInfo1.parsePrivateKey(), privInfo1.getAttributes(), privInfo1.getPublicKeyData().getOctets());

        isTrue("enc 2 failed", areEqual(privWithPub, privInfo2.getEncoded()));
    }

    public static void main(
        String[]    args)
    {
        runTest(new PrivateKeyInfoTest());
    }
}