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. 
package org.bouncycastle.asn1;

import java.io.IOException;
import java.io.InputStream;

public class DEROctetStringParser
    implements ASN1OctetStringParser
{
    private DefiniteLengthInputStream stream;

    DEROctetStringParser(
        DefiniteLengthInputStream stream)
    {
        this.stream = stream;
    }

    public InputStream getOctetStream()
    {
        return stream;
    }

    public DERObject getLoadedObject()
        throws IOException
    {
        return new DEROctetString(stream.toByteArray());
    }
    
    public DERObject getDERObject()
    {
        try
        {
            return getLoadedObject();
        }
        catch (IOException e)
        {
            throw new ASN1ParsingException("IOException converting stream to byte array: " + e.getMessage(), e);
        }
    }
}