1 /*
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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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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      */
ATR(byte[] atr)59     public ATR(byte[] atr) {
60         this.atr = atr.clone();
61         parse();
62     }
63 
parse()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      */
getBytes()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      */
getHistoricalBytes()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      */
toString()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      */
equals(Object obj)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      */
hashCode()155     public int hashCode() {
156         return Arrays.hashCode(atr);
157     }
158 
readObject(java.io.ObjectInputStream in)159     private void readObject(java.io.ObjectInputStream in)
160             throws java.io.IOException, ClassNotFoundException {
161         atr = (byte[])in.readUnshared();
162         parse();
163     }
164 
165 }
166