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 java.io.ByteArrayOutputStream;

import org.bouncycastle.asn1.DEROutputStream;
import org.bouncycastle.asn1.cmc.CertificationRequest;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Base64;
import org.bouncycastle.util.test.SimpleTest;

public class CMCCertificationRequestTest
    extends SimpleTest
{
    byte[]    req1 = Base64.decode(
                "MIHoMIGTAgEAMC4xDjAMBgNVBAMTBVRlc3QyMQ8wDQYDVQQKEwZBbmFUb20xCzAJBgNVBAYTAlNF"
            +   "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALlEt31Tzt2MlcOljvacJgzQVhmlMoqAOgqJ9Pgd3Gux"
            +   "Z7/WcIlgW4QCB7WZT21O1YoghwBhPDMcNGrHei9kHQkCAwEAAaAAMA0GCSqGSIb3DQEBBQUAA0EA"
            +   "NDEI4ecNtJ3uHwGGlitNFq9WxcoZ0djbQJ5hABMotav6gtqlrwKXY2evaIrsNwkJtNdwwH18aQDU"
            +   "KCjOuBL38Q==");

    byte[]    req2 = Base64.decode(
               "MIIB6TCCAVICAQAwgagxCzAJBgNVBAYTAlVTMRMwEQYDVQQIEwpDYWxpZm9ybmlhMRQwEgYDVQQH"
            +  "EwtTYW50YSBDbGFyYTEMMAoGA1UEChMDQUJCMVEwTwYDVQQLHEhQAAAAAAAAAG8AAAAAAAAAdwAA"
            +  "AAAAAABlAAAAAAAAAHIAAAAAAAAAIAAAAAAAAABUAAAAAAAAABxIAAAAAAAARAAAAAAAAAAxDTAL"
            +  "BgNVBAMTBGJsdWUwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBANETRZ+6occCOrFxNhfKIp4C"
            +  "mMkxwhBNb7TnnahpbM9O0r4hrBPcfYuL7u9YX/jN0YNUP+/CiT39HhSe/bikaBPDEyNsl988I8vX"
            +  "piEdgxYq/+LTgGHbjRsRYCkPtmzwBbuBldNF8bV7pu0v4UScSsExmGqqDlX1TbPU8KkPU1iTAgMB"
            +  "AAGgADANBgkqhkiG9w0BAQQFAAOBgQAFbrs9qUwh93CtETk7DeUD5HcdCnxauo1bck44snSV6MZV"
            +  "OCIGaYu1501kmhEvAtVVRr6SEHwimfQDDIjnrWwYsEr/DT6tkTZAbfRd3qUu3iKjT0H0vlUZp0hJ"
            +  "66mINtBM84uZFBfoXiWY8M3FuAnGmvy6ah/dYtJorTxLKiGkew==");

    public String getName()
    {
        return "CMCCertificationRequestTest";
    }
    
    public void certReqTest(
        String  testName,
        byte[]  req)
        throws Exception
    {
        CertificationRequest    r = CertificationRequest.getInstance(req);

        ByteArrayOutputStream    bOut = new ByteArrayOutputStream();
        DEROutputStream          dOut = new DEROutputStream(bOut);

        dOut.writeObject(r.toASN1Primitive());

        byte[]                    bytes = bOut.toByteArray();

        if (bytes.length != req.length)
        {
            fail(testName + " failed length test");
        }

        for (int i = 0; i != req.length; i++)
        {
            if (bytes[i] != req[i])
            {
                fail(testName + " failed comparison test");
            }
        }
    }

    public void performTest()
        throws Exception
    {
        certReqTest("req1", req1);
        certReqTest("req2", req2);

        CertificationRequest    a = CertificationRequest.getInstance(req1);
        CertificationRequest    b = new CertificationRequest(a.getSubject(), a.getSubjectPublicKeyAlgorithm(), a.getSubjectPublicKey(), a.getAttributes(), a.getSignatureAlgorithm(), a.getSignature());

        isTrue(Arrays.areEqual(a.getEncoded(), b.getEncoded()));
    }


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