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 1.7. 
package org.bouncycastle.asn1;


basic interface for DER string objects.

/**
 * basic interface for DER string objects.
 */
public interface DERString
    extends ASN1String
{

}