MifareUltralight.java revision 39cf3a445e507f219ecc8a476f6038f095d9d520 
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 *
55 * <p class="note"><strong>Note:</strong> Methods that perform I/O operations
56 * require the {@link android.Manifest.permission#NFC} permission.
57 */
58public final class MifareUltralight extends BasicTagTechnology {
59    /** A MIFARE Ultralight compatible tag of unknown type */
60    public static final int TYPE_UNKNOWN = -1;
61    /** A MIFARE Ultralight tag */
62    public static final int TYPE_ULTRALIGHT = 1;
63    /** A MIFARE Ultralight C tag */
64    public static final int TYPE_ULTRALIGHT_C = 2;
65
66    /** Size of a MIFARE Ultralight page in bytes */
67    public static final int PAGE_SIZE = 4;
68
69    private static final int NXP_MANUFACTURER_ID = 0x04;
70    private static final int MAX_PAGE_COUNT = 256;
71
72    private int mType;
73
74    /**
75     * Get an instance of {@link MifareUltralight} for the given tag.
76     * <p>Returns null if {@link MifareUltralight} was not enumerated in
77     * {@link Tag#getTechList} - this indicates the tag is not MIFARE
78     * Ultralight compatible, or that this Android
79     * device does not implement MIFARE Ultralight.
80     * <p>Does not cause any RF activity and does not block.
81     *
82     * @param tag an MIFARE Ultralight compatible tag
83     * @return MIFARE Ultralight object
84     */
85    public static MifareUltralight get(Tag tag) {
86        if (!tag.hasTech(TagTechnology.MIFARE_ULTRALIGHT)) return null;
87        try {
88            return new MifareUltralight(tag);
89        } catch (RemoteException e) {
90            return null;
91        }
92    }
93
94    /** @hide */
95    public MifareUltralight(Tag tag) throws RemoteException {
96        super(tag, TagTechnology.MIFARE_ULTRALIGHT);
97
98        // Check if this could actually be a Mifare
99        NfcA a = NfcA.get(tag);
100
101        mType = TYPE_UNKNOWN;
102
103        if (a.getSak() == 0x00 && tag.getId()[0] == NXP_MANUFACTURER_ID) {
104            // could be UL or UL-C
105            //TODO: stack should use NXP AN1303 procedure to make a best guess
106            // attempt at classifying Ultralight vs Ultralight C.
107            mType = TYPE_ULTRALIGHT;
108        }
109    }
110
111    /**
112     * Return the MIFARE Ultralight type of the tag.
113     * <p>One of {@link #TYPE_ULTRALIGHT} or {@link #TYPE_ULTRALIGHT_C} or
114     * {@link #TYPE_UNKNOWN}.
115     * <p>Depending on how the tag has been formatted, it can be impossible
116     * to accurately classify between original MIFARE Ultralight and
117     * Ultralight C. So treat this method as a hint.
118     * <p>Does not cause any RF activity and does not block.
119     *
120     * @return the type
121     */
122    public int getType() {
123        return mType;
124    }
125
126    /**
127     * Read 4 pages (16 bytes).
128     *
129     * <p>The MIFARE Ultralight protocol always reads 4 pages at a time, to
130     * reduce the number of commands required to read an entire tag.
131     * <p>If a read spans past the last readable block, then the tag will
132     * return pages that have been wrapped back to the first blocks. MIFARE
133     * Ultralight tags have readable blocks 0x00 through 0x0F. So a read to
134     * block offset 0x0E would return blocks 0x0E, 0x0F, 0x00, 0x01. MIFARE
135     * Ultralight C tags have readable blocks 0x00 through 0x2B. So a read to
136     * block 0x2A would return blocks 0x2A, 0x2B, 0x00, 0x01.
137     *
138     * <p>This is an I/O operation and will block until complete. It must
139     * not be called from the main application thread. A blocked call will be canceled with
140     * {@link IOException} if {@link #close} is called from another thread.
141     *
142     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
143     *
144     * @param pageOffset index of first page to read, starting from 0
145     * @return 4 pages (16 bytes)
146     * @throws TagLostException if the tag leaves the field
147     * @throws IOException if there is an I/O failure, or the operation is canceled
148     */
149    public byte[] readPages(int pageOffset) throws IOException {
150        validatePageIndex(pageOffset);
151        checkConnected();
152
153        byte[] cmd = { 0x30, (byte) pageOffset};
154        return transceive(cmd, false);
155    }
156
157    /**
158     * Write 1 page (4 bytes).
159     *
160     * <p>The MIFARE Ultralight protocol always writes 1 page at a time, to
161     * minimize EEPROM write cycles.
162     *
163     * <p>This is an I/O operation and will block until complete. It must
164     * not be called from the main application thread. A blocked call will be canceled with
165     * {@link IOException} if {@link #close} is called from another thread.
166     *
167     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
168     *
169     * @param pageOffset index of page to write, starting from 0
170     * @param data 4 bytes to write
171     * @throws TagLostException if the tag leaves the field
172     * @throws IOException if there is an I/O failure, or the operation is canceled
173     */
174    public void writePage(int pageOffset, byte[] data) throws IOException {
175        validatePageIndex(pageOffset);
176        checkConnected();
177
178        byte[] cmd = new byte[data.length + 2];
179        cmd[0] = (byte) 0xA2;
180        cmd[1] = (byte) pageOffset;
181        System.arraycopy(data, 0, cmd, 2, data.length);
182
183        transceive(cmd, false);
184    }
185
186    /**
187     * Send raw NfcA data to a tag and receive the response.
188     *
189     * <p>This is equivalent to connecting to this tag via {@link NfcA}
190     * and calling {@link NfcA#transceive}. Note that all MIFARE Classic
191     * tags are based on {@link NfcA} technology.
192     *
193     * <p>This is an I/O operation and will block until complete. It must
194     * not be called from the main application thread. A blocked call will be canceled with
195     * {@link IOException} if {@link #close} is called from another thread.
196     *
197     * <p class="note">Requires the {@link android.Manifest.permission#NFC} permission.
198     *
199     * @see NfcA#transceive
200     */
201    public byte[] transceive(byte[] data) throws IOException {
202        return transceive(data, true);
203    }
204
205    private static void validatePageIndex(int pageIndex) {
206        // Do not be too strict on upper bounds checking, since some cards
207        // may have more addressable memory than they report.
208        // Note that issuing a command to an out-of-bounds block is safe - the
209        // tag will wrap the read to an addressable area. This validation is a
210        // helper to guard against obvious programming mistakes.
211        if (pageIndex < 0 || pageIndex >= MAX_PAGE_COUNT) {
212            throw new IndexOutOfBoundsException("page out of bounds: " + pageIndex);
213        }
214    }
215}
216