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.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.nist.NISTObjectIdentifiers;
import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers;

public class SMIMECapability
    extends ASN1Encodable
{
    
general preferences

/**
     * general preferences
     */
    public static final DERObjectIdentifier preferSignedData = PKCSObjectIdentifiers.preferSignedData;
    public static final DERObjectIdentifier canNotDecryptAny = PKCSObjectIdentifiers.canNotDecryptAny;
    public static final DERObjectIdentifier sMIMECapabilitiesVersions = PKCSObjectIdentifiers.sMIMECapabilitiesVersions;

    
encryption algorithms preferences

/**
     * encryption algorithms preferences
     */
    public static final DERObjectIdentifier dES_CBC = new DERObjectIdentifier("1.3.14.3.2.7");
    public static final DERObjectIdentifier dES_EDE3_CBC = PKCSObjectIdentifiers.des_EDE3_CBC;
    public static final DERObjectIdentifier rC2_CBC = PKCSObjectIdentifiers.RC2_CBC;
    public static final DERObjectIdentifier aES128_CBC = NISTObjectIdentifiers.id_aes128_CBC;
    public static final DERObjectIdentifier aES192_CBC = NISTObjectIdentifiers.id_aes192_CBC;
    public static final DERObjectIdentifier aES256_CBC = NISTObjectIdentifiers.id_aes256_CBC;
    
    private DERObjectIdentifier capabilityID;
    private DEREncodable        parameters;

    public SMIMECapability(
        ASN1Sequence seq)
    {
        capabilityID = (DERObjectIdentifier)seq.getObjectAt(0);

        if (seq.size() > 1)
        {
            parameters = (DERObject)seq.getObjectAt(1);
        }
    }

    public SMIMECapability(
        DERObjectIdentifier capabilityID,
        DEREncodable        parameters)
    {
        this.capabilityID = capabilityID;
        this.parameters = parameters;
    }
    
    public static SMIMECapability getInstance(
        Object obj)
    {
        if (obj == null || obj instanceof SMIMECapability)
        {
            return (SMIMECapability)obj;
        }
        
        if (obj instanceof ASN1Sequence)
        {
            return new SMIMECapability((ASN1Sequence)obj);
        }
        
        throw new IllegalArgumentException("Invalid SMIMECapability");
    } 

    public DERObjectIdentifier getCapabilityID()
    {
        return capabilityID;
    }

    public DEREncodable getParameters()
    {
        return parameters;
    }

    
Produce an object suitable for an ASN1OutputStream.

 
SMIMECapability ::= SEQUENCE {
    capabilityID OBJECT IDENTIFIER,
    parameters ANY DEFINED BY capabilityID OPTIONAL 
}



/**
     * Produce an object suitable for an ASN1OutputStream.
     * <pre> 
     * SMIMECapability ::= SEQUENCE {
     *     capabilityID OBJECT IDENTIFIER,
     *     parameters ANY DEFINED BY capabilityID OPTIONAL 
     * }
     * </pre>
     */
    public DERObject toASN1Object()
    {
        ASN1EncodableVector  v = new ASN1EncodableVector();

        v.add(capabilityID);
        
        if (parameters != null)
        {
            v.add(parameters);
        }
        
        return new DERSequence(v);
    }
}