MifareUltralight.java revision 46797ac098e90cbef5c266b75fb37fc06e9acc80 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.nfc.tech;
18
19import android.nfc.Tag;
20import android.nfc.TagLostException;
21import android.os.RemoteException;
22
23import java.io.IOException;
24
25//TOOD: Ultralight C 3-DES authentication, one-way counter
26
27/**
28 * Provides access to MIFARE Ultralight properties and I/O operations on a {@link Tag}.
29 *
30 * <p>Acquire a {@link MifareUltralight} object using {@link #get}.
31 *
32 * <p>MIFARE Ultralight compatible tags have 4 byte pages {@link #PAGE_SIZE}.
33 * The primary operations on an Ultralight tag are {@link #readPages} and
34 * {@link #writePage}.
35 *
36 * <p>The original MIFARE Ultralight consists of a 64 byte EEPROM. The first
37 * 4 pages are for the OTP area, manufacturer data, and locking bits. They are
38 * readable and some bits are writable. The final 12 pages are the user
39 * read/write area. For more information see the NXP data sheet MF0ICU1.
40 *
41 * <p>The MIFARE Ultralight C consists of a 192 byte EEPROM. The first 4 pages
42 * are for OTP, manufacturer data, and locking bits. The next 36 pages are the
43 * user read/write area. The next 4 pages are additional locking bits, counters
44 * and authentication configuration and are readable. The final 4 pages are for
45 * the authentication key and are not readable. For more information see the
46 * NXP data sheet MF0ICU2.
47 *
48 * <p>Implementation of this class on a Android NFC device is optional.
49 * If it is not implemented, then
50 * {@link MifareUltralight} will never be enumerated in {@link Tag#getTechList}.
51 * If it is enumerated, then all {@link MifareUltralight} I/O operations will be supported.
52 * In either case, {@link NfcA} will also be enumerated on the tag,
53 * because all MIFARE Ultralight tags are also {@link NfcA} tags.
54 */
55public final class MifareUltralight extends BasicTagTechnology {
56    /** A MIFARE Ultralight compatible tag of unknown type */
57    public static final int TYPE_UNKNOWN = -1;
58    /** A MIFARE Ultralight tag */
59    public static final int TYPE_ULTRALIGHT = 1;
60    /** A MIFARE Ultralight C tag */
61    public static final int TYPE_ULTRALIGHT_C = 2;
62
63    /** Size of a MIFARE Ultralight page in bytes */
64    public static final int PAGE_SIZE = 4;
65
66    private static final int NXP_MANUFACTURER_ID = 0x04;
67    private static final int MAX_PAGE_COUNT = 256;
68
69    private int mType;
70
71    /**
72     * Get an instance of {@link MifareUltralight} for the given tag.
73     * <p>Returns null if {@link MifareUltralight} was not enumerated in
74     * {@link Tag#getTechList} - this indicates the tag is not MIFARE
75     * Ultralight compatible, or that this Android
76     * device does not implement MIFARE Ultralight.
77     * <p>Does not cause any RF activity and does not block.
78     *
79     * @param tag an MIFARE Ultralight compatible tag
80     * @return MIFARE Ultralight object
81     */
82    public static MifareUltralight get(Tag tag) {
83        if (!tag.hasTech(TagTechnology.MIFARE_ULTRALIGHT)) return null;
84        try {
85            return new MifareUltralight(tag);
86        } catch (RemoteException e) {
87            return null;
88        }
89    }
90
91    /** @hide */
92    public MifareUltralight(Tag tag) throws RemoteException {
93        super(tag, TagTechnology.MIFARE_ULTRALIGHT);
94
95        // Check if this could actually be a Mifare
96        NfcA a = NfcA.get(tag);
97
98        mType = TYPE_UNKNOWN;
99
100        if (a.getSak() == 0x00 && tag.getId()[0] == NXP_MANUFACTURER_ID) {
101            // could be UL or UL-C
102            //TODO: stack should use NXP AN1303 procedure to make a best guess
103            // attempt at classifying Ultralight vs Ultralight C.
104            mType = TYPE_ULTRALIGHT;
105        }
106    }
107
108    /**
109     * Return the MIFARE Ultralight type of the tag.
110     * <p>One of {@link #TYPE_ULTRALIGHT} or {@link #TYPE_ULTRALIGHT_C} or
111     * {@link #TYPE_UNKNOWN}.
112     * <p>Depending on how the tag has been formatted, it can be impossible
113     * to accurately classify between original MIFARE Ultralight and
114     * Ultralight C. So treat this method as a hint.
115     * <p>Does not cause any RF activity and does not block.
116     *
117     * @return the type
118     */
119    public int getType() {
120        return mType;
121    }
122
123    /**
124     * Read 4 pages (16 bytes).
125     *
126     * <p>The MIFARE Ultralight protocol always reads 4 pages at a time, to
127     * reduce the number of commands required to read an entire tag.
128     * <p>If a read spans past the last readable block, then the tag will
129     * return pages that have been wrapped back to the first blocks. MIFARE
130     * Ultralight tags have readable blocks 0x00 through 0x0F. So a read to
131     * block offset 0x0E would return blocks 0x0E, 0x0F, 0x00, 0x01. MIFARE
132     * Ultralight C tags have readable blocks 0x00 through 0x2B. So a read to
133     * block 0x2A would return blocks 0x2A, 0x2B, 0x00, 0x01.
134     *
135     * <p>This is an I/O operation and will block until complete. It must
136     * not be called from the main application thread. A blocked call will be canceled with
137     * {@link IOException} if {@link #close} is called from another thread.
138     *
139     * @param pageOffset index of first page to read, starting from 0
140     * @return 4 pages (16 bytes)
141     * @throws TagLostException if the tag leaves the field
142     * @throws IOException if there is an I/O failure, or the operation is canceled
143     */
144    public byte[] readPages(int pageOffset) throws IOException {
145        validatePageIndex(pageOffset);
146        checkConnected();
147
148        byte[] cmd = { 0x30, (byte) pageOffset};
149        return transceive(cmd, false);
150    }
151
152    /**
153     * Write 1 page (4 bytes).
154     *
155     * <p>The MIFARE Ultralight protocol always writes 1 page at a time, to
156     * minimize EEPROM write cycles.
157     *
158     * <p>This is an I/O operation and will block until complete. It must
159     * not be called from the main application thread. A blocked call will be canceled with
160     * {@link IOException} if {@link #close} is called from another thread.
161     *
162     * @param pageOffset index of page to write, starting from 0
163     * @param data 4 bytes to write
164     * @throws TagLostException if the tag leaves the field
165     * @throws IOException if there is an I/O failure, or the operation is canceled
166     */
167    public void writePage(int pageOffset, byte[] data) throws IOException {
168        validatePageIndex(pageOffset);
169        checkConnected();
170
171        byte[] cmd = new byte[data.length + 2];
172        cmd[0] = (byte) 0xA2;
173        cmd[1] = (byte) pageOffset;
174        System.arraycopy(data, 0, cmd, 2, data.length);
175
176        transceive(cmd, false);
177    }
178
179    /**
180     * Send raw NfcA data to a tag and receive the response.
181     *
182     * <p>This is equivalent to connecting to this tag via {@link NfcA}
183     * and calling {@link NfcA#transceive}. Note that all MIFARE Classic
184     * tags are based on {@link NfcA} technology.
185     *
186     * <p>This is an I/O operation and will block until complete. It must
187     * not be called from the main application thread. A blocked call will be canceled with
188     * {@link IOException} if {@link #close} is called from another thread.
189     *
190     * @see NfcA#transceive
191     */
192    public byte[] transceive(byte[] data) throws IOException {
193        return transceive(data, true);
194    }
195
196    private static void validatePageIndex(int pageIndex) {
197        // Do not be too strict on upper bounds checking, since some cards
198        // may have more addressable memory than they report.
199        // Note that issuing a command to an out-of-bounds block is safe - the
200        // tag will wrap the read to an addressable area. This validation is a
201        // helper to guard against obvious programming mistakes.
202        if (pageIndex < 0 || pageIndex >= MAX_PAGE_COUNT) {
203            throw new IndexOutOfBoundsException("page out of bounds: " + pageIndex);
204        }
205    }
206}
207