static final int DEVICE_CLAIMS_TYPE = 0xF;

    static final int LOGON_EXTRA_SIDS = 0x20;
    static final int LOGON_RESOURCE_GROUPS = 0x200;

    static final int MD5_KRB_SALT = 17;
    static final int MD5_BLOCK_LENGTH = 64;

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;


@SuppressWarnings ( "javadoc" )
public class PacSignature {

    public static final int KERB_CHECKSUM_HMAC_MD5 = 0xFFFFFF76;
    public static final int HMAC_SHA1_96_AES128 = 0x0000000F;
    public static final int HMAC_SHA1_96_AES256 = 0x00000010;

    public static final int ETYPE_ARCFOUR_HMAC = 23;

    public SigningDigest(byte[] macSigningKey, boolean bypass) throws SmbException {
        try {
            digest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException ex) {
            if( log.level > 0 )
                ex.printStackTrace( log );
            throw new SmbException( "MD5", ex );
        }

        this.macSigningKey = macSigningKey;
        this.bypass = bypass;
        this.updates = 0;

 *
 */
public interface SMBSigningDigest {

    /**
     * Performs MAC signing of the SMB. This is done as follows.
     * The signature field of the SMB is overwritten with the sequence number;
     * The MD5 digest of the MAC signing key + the entire SMB is taken;
     * The first 8 bytes of this are placed in the signature field.
     *
     * @param data
     *            The data.
     * @param offset

        byte[] sessionHash = new byte[8];

        MessageDigest md5 = Crypto.getMD5();;
        md5.update(serverChallenge);
        md5.update(clientChallenge, 0, 8);
        System.arraycopy(md5.digest(), 0, sessionHash, 0, 8);

        byte[] key = new byte[21];
        System.arraycopy(passwordHash, 0, key, 0, 16);

        }
    }


    private static byte[] deriveKey ( byte[] masterKey, String cnst ) {
        MessageDigest md5 = Crypto.getMD5();
        md5.update(masterKey);
        md5.update(cnst.getBytes(StandardCharsets.US_ASCII));
        md5.update((byte) 0);
        return md5.digest();
    }


    @Override
    public boolean supportsIntegrity () {
        return true;
    }

    }

    protected byte[] engineDigest() {
        byte[] digest = md5.digest();
        md5.update(opad);
        return md5.digest(digest);
    }

    protected int engineDigest(byte[] buf, int offset, int len) {
        byte[] digest = md5.digest();
        md5.update(opad);
        md5.update(digest);
        try {
            return md5.digest(buf, offset, len);
        } catch (Exception ex) {

        byte[] digest = this.md5.digest();
        this.md5.update(this.opad);
        return this.md5.digest(digest);
    }


    @Override
    protected int engineDigest ( byte[] buf, int offset, int len ) {
        byte[] digest = this.md5.digest();
        this.md5.update(this.opad);
        this.md5.update(digest);
        try {
            return this.md5.digest(buf, offset, len);
        }

        if ("sha512".equalsIgnoreCase(digestAlgorism)) {
            oneWay = OneWayCryptographer.createSha512Cryptographer();
        } else if ("md5".equalsIgnoreCase(digestAlgorism)) {
            oneWay = new OneWayCryptographer("MD5", OneWayCryptographer.ENCODING_UTF8);
        } else {
            oneWay = OneWayCryptographer.createSha256Cryptographer();
        }

        int ms_usage = mapArcfourMD5KeyUsage(keyusage);
        Mac mac = Mac.getInstance("HmacMD5");
        MessageDigest md = MessageDigest.getInstance("MD5");
        mac.init(key);
        byte[] dk = mac.doFinal(MD5_CONSTANT);
        try {
            // little endian
            md.update((byte) ( ms_usage & 0xFF ));
            md.update((byte) ( ( ms_usage >> 8 ) & 0xFF ));