http://www.bouncycastle.org/java.html: The Bouncy Castle Java APIs for CMS, PKCS, EAC, TSP, CMP, CRMF, OCSP, and certificate generation. This jar contains APIs for JDK 1.5 to JDK 1.8. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.
  • The Legion of the Bouncy Castle Inc. 
package org.bouncycastle.cms.jcajce;

import java.io.IOException;

import org.bouncycastle.asn1.ASN1Encoding;
import org.bouncycastle.asn1.cms.ecc.ECCCMSSharedInfo;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;
import org.bouncycastle.util.Pack;

class RFC5753KeyMaterialGenerator
    implements KeyMaterialGenerator
{
    public byte[] generateKDFMaterial(AlgorithmIdentifier keyAlgorithm, int keySize, byte[] userKeyMaterialParameters)
    {
        ECCCMSSharedInfo eccInfo = new ECCCMSSharedInfo(keyAlgorithm, userKeyMaterialParameters, Pack.intToBigEndian(keySize));

        try
        {
            return eccInfo.getEncoded(ASN1Encoding.DER);
        }
        catch (IOException e)
        {
            throw new IllegalStateException("Unable to create KDF material: " + e);
        }
    }
}