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.tsp.cms;

import java.io.IOException;

import org.bouncycastle.asn1.ASN1Encoding;
import org.bouncycastle.asn1.ASN1String;
import org.bouncycastle.asn1.cms.Attributes;
import org.bouncycastle.asn1.cms.MetaData;
import org.bouncycastle.cms.CMSException;
import org.bouncycastle.operator.DigestCalculator;

class MetaDataUtil
{
    private final MetaData          metaData;

    MetaDataUtil(MetaData metaData)
    {
        this.metaData = metaData;
    }

    void initialiseMessageImprintDigestCalculator(DigestCalculator calculator)
        throws CMSException
    {
        if (metaData != null && metaData.isHashProtected())
        {
            try
            {
                calculator.getOutputStream().write(metaData.getEncoded(ASN1Encoding.DER));
            }
            catch (IOException e)
            {
                throw new CMSException("unable to initialise calculator from metaData: " + e.getMessage(), e);
            }
        }
    }

    String getFileName()
    {
        if (metaData != null)
        {
            return convertString(metaData.getFileName());
        }

        return null;
    }

    String getMediaType()
    {
        if (metaData != null)
        {
            return convertString(metaData.getMediaType());
        }

        return null;
    }

    Attributes getOtherMetaData()
    {
        if (metaData != null)
        {
            return metaData.getOtherMetaData();
        }

        return null;
    }

    private String convertString(ASN1String s)
    {
        if (s != null)
        {
            return s.toString();
        }

        return null;
    }
}