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.smime;

import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.DERSet;
import org.bouncycastle.asn1.DERTaggedObject;
import org.bouncycastle.asn1.cms.Attribute;
import org.bouncycastle.asn1.cms.IssuerAndSerialNumber;
import org.bouncycastle.asn1.cms.RecipientKeyIdentifier;


The SMIMEEncryptionKeyPreference object.

SMIMEEncryptionKeyPreference ::= CHOICE {
    issuerAndSerialNumber   [0] IssuerAndSerialNumber,
    receipentKeyId          [1] RecipientKeyIdentifier,
    subjectAltKeyIdentifier [2] SubjectKeyIdentifier
}



/**
 * The SMIMEEncryptionKeyPreference object.
 * <pre>
 * SMIMEEncryptionKeyPreference ::= CHOICE {
 *     issuerAndSerialNumber   [0] IssuerAndSerialNumber,
 *     receipentKeyId          [1] RecipientKeyIdentifier,
 *     subjectAltKeyIdentifier [2] SubjectKeyIdentifier
 * }
 * </pre>
 */
public class SMIMEEncryptionKeyPreferenceAttribute
    extends Attribute
{
    public SMIMEEncryptionKeyPreferenceAttribute(
        IssuerAndSerialNumber issAndSer)
    {
        super(SMIMEAttributes.encrypKeyPref,
                new DERSet(new DERTaggedObject(false, 0, issAndSer)));
    }
    
    public SMIMEEncryptionKeyPreferenceAttribute(
        RecipientKeyIdentifier rKeyId)
    {

        super(SMIMEAttributes.encrypKeyPref, 
                    new DERSet(new DERTaggedObject(false, 1, rKeyId)));
    }
    
    
Params:
  • sKeyId – the subjectKeyIdentifier value (normally the X.509 one)
/**
     * @param sKeyId the subjectKeyIdentifier value (normally the X.509 one)
     */
    public SMIMEEncryptionKeyPreferenceAttribute(
        ASN1OctetString sKeyId)
    {

        super(SMIMEAttributes.encrypKeyPref,
                    new DERSet(new DERTaggedObject(false, 2, sKeyId)));
    }
}