*
 * This class provides helper methods for working with ASN.1
 * encoded data structures used in Kerberos PAC processing.
 */
public final class ASN1Util {

    private ASN1Util() {
    }

    /**
     * Casts an object to the specified type with type checking
     * @param <T> the target type
     * @param type the target class type
     * @param object the object to cast

                DERGeneralString derRealm = ASN1Util.as(DERGeneralString.class, tagged);
                this.userRealm = derRealm.getString();
                break;
            case 3: // Principal
                ASN1Sequence principalSequence = ASN1Util.as(ASN1Sequence.class, tagged);
                ASN1Sequence nameSequence = ASN1Util.as(ASN1Sequence.class, ASN1Util.as(ASN1TaggedObject.class, principalSequence, 1));

        while (authElements.hasMoreElements()) {
            ASN1Sequence authElement = ASN1Util.as(ASN1Sequence.class, authElements);
            ASN1Integer authType = ASN1Util.as(ASN1Integer.class, ASN1Util.as(ASN1TaggedObject.class, authElement, 0));
            DEROctetString authData = ASN1Util.as(DEROctetString.class, ASN1Util.as(ASN1TaggedObject.class, authElement, 1));

import org.bouncycastle.asn1.ASN1ObjectIdentifier;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.BERTags;

import jcifs.pac.ASN1Util;
import jcifs.pac.PACDecodingException;

/**
 * Represents a Kerberos authentication token.
 */
public class KerberosToken {

    private KerberosApRequest apRequest;

    /**

            case 3:// Encrypted part
                ASN1Sequence encSequence = ASN1Util.as(ASN1Sequence.class, tagged);
                ASN1Integer encType = ASN1Util.as(ASN1Integer.class, ASN1Util.as(ASN1TaggedObject.class, encSequence, 0));
                DEROctetString encOctets = ASN1Util.as(DEROctetString.class, ASN1Util.as(ASN1TaggedObject.class, encSequence, 2));
                byte[] crypt = encOctets.getOctets();

        Enumeration<?> fields = seq.getObjects();
        while (fields.hasMoreElements()) {
            ASN1TaggedObject tagged = ASN1Util.as(ASN1TaggedObject.class, fields.nextElement());
            switch (tagged.getTagNo()) {
            case 0:
                ASN1Integer pvno = ASN1Util.as(ASN1Integer.class, tagged);
                if (!pvno.getValue().equals(new BigInteger(KerberosConstants.KERBEROS_VERSION))) {