      1 /*
      2  * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
      3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
      4  *
      5  * This code is free software; you can redistribute it and/or modify it
      6  * under the terms of the GNU General Public License version 2 only, as
      7  * published by the Free Software Foundation.  Oracle designates this
      8  * particular file as subject to the "Classpath" exception as provided
      9  * by Oracle in the LICENSE file that accompanied this code.
     10  *
     11  * This code is distributed in the hope that it will be useful, but WITHOUT
     12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     14  * version 2 for more details (a copy is included in the LICENSE file that
     15  * accompanied this code).
     16  *
     17  * You should have received a copy of the GNU General Public License version
     18  * 2 along with this work; if not, write to the Free Software Foundation,
     19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
     20  *
     21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
     22  * or visit www.oracle.com if you need additional information or have any
     23  * questions.
     24  */
     25
     26 package javax.smartcardio;
     27
     28 import java.util.*;
     29
     30 /**
     31  * A Smart Card's answer-to-reset bytes. A Card's ATR object can be obtained
     32  * by calling {@linkplain Card#getATR}.
     33  * This class does not attempt to verify that the ATR encodes a semantically
     34  * valid structure.
     35  *
     36  * <p>Instances of this class are immutable. Where data is passed in or out
     37  * via byte arrays, defensive cloning is performed.
     38  *
     39  * @see Card#getATR
     40  *
     41  * @since   1.6
     42  * @author  Andreas Sterbenz
     43  * @author  JSR 268 Expert Group
     44  */
     45 public final class ATR implements java.io.Serializable {
     46
     47     private static final long serialVersionUID = 6695383790847736493L;
     48
     49     private byte[] atr;
     50
     51     private transient int startHistorical, nHistorical;
     52
     53     /**
     54      * Constructs an ATR from a byte array.
     55      *
     56      * @param atr the byte array containing the answer-to-reset bytes
     57      * @throws NullPointerException if <code>atr</code> is null
     58      */
     59     public ATR(byte[] atr) {
     60         this.atr = atr.clone();
     61         parse();
     62     }
     63
     64     private void parse() {
     65         if (atr.length < 2) {
     66             return;
     67         }
     68         if ((atr[0] != 0x3b) && (atr[0] != 0x3f)) {
     69             return;
     70         }
     71         int t0 = (atr[1] & 0xf0) >> 4;
     72         int n = atr[1] & 0xf;
     73         int i = 2;
     74         while ((t0 != 0) && (i < atr.length)) {
     75             if ((t0 & 1) != 0) {
     76                 i++;
     77             }
     78             if ((t0 & 2) != 0) {
     79                 i++;
     80             }
     81             if ((t0 & 4) != 0) {
     82                 i++;
     83             }
     84             if ((t0 & 8) != 0) {
     85                 if (i >= atr.length) {
     86                     return;
     87                 }
     88                 t0 = (atr[i++] & 0xf0) >> 4;
     89             } else {
     90                 t0 = 0;
     91             }
     92         }
     93         int k = i + n;
     94         if ((k == atr.length) || (k == atr.length - 1)) {
     95             startHistorical = i;
     96             nHistorical = n;
     97         }
     98     }
     99
    100     /**
    101      * Returns a copy of the bytes in this ATR.
    102      *
    103      * @return a copy of the bytes in this ATR.
    104      */
    105     public byte[] getBytes() {
    106         return atr.clone();
    107     }
    108
    109     /**
    110      * Returns a copy of the historical bytes in this ATR.
    111      * If this ATR does not contain historical bytes, an array of length
    112      * zero is returned.
    113      *
    114      * @return a copy of the historical bytes in this ATR.
    115      */
    116     public byte[] getHistoricalBytes() {
    117         byte[] b = new byte[nHistorical];
    118         System.arraycopy(atr, startHistorical, b, 0, nHistorical);
    119         return b;
    120     }
    121
    122     /**
    123      * Returns a string representation of this ATR.
    124      *
    125      * @return a String representation of this ATR.
    126      */
    127     public String toString() {
    128         return "ATR: " + atr.length + " bytes";
    129     }
    130
    131     /**
    132      * Compares the specified object with this ATR for equality.
    133      * Returns true if the given object is also an ATR and its bytes are
    134      * identical to the bytes in this ATR.
    135      *
    136      * @param obj the object to be compared for equality with this ATR
    137      * @return true if the specified object is equal to this ATR
    138      */
    139     public boolean equals(Object obj) {
    140         if (this == obj) {
    141             return true;
    142         }
    143         if (obj instanceof ATR == false) {
    144             return false;
    145         }
    146         ATR other = (ATR)obj;
    147         return Arrays.equals(this.atr, other.atr);
    148     }
    149
    150     /**
    151      * Returns the hash code value for this ATR.
    152      *
    153      * @return the hash code value for this ATR.
    154      */
    155     public int hashCode() {
    156         return Arrays.hashCode(atr);
    157     }
    158
    159     private void readObject(java.io.ObjectInputStream in)
    160             throws java.io.IOException, ClassNotFoundException {
    161         atr = (byte[])in.readUnshared();
    162         parse();
    163     }
    164
    165 }