864e7b07d9bf5a58cf757a490545fedad46f76ac
[YkNeoCR.git] / src / org / average / nfcauthcr / YkNeo.java
1 package org.average.ykneocr;
2
3 import java.io.IOException;
4 import java.lang.String;
5 import java.util.ArrayList;
6 import java.util.Arrays;
7
8 import android.nfc.NfcAdapter;
9 import android.nfc.Tag;
10 import android.nfc.tech.IsoDep;
11
12 import org.average.ykneocr.CRException;
13
14 public class YkNeo {
15
16         // http://forum.yubico.com/viewtopic.php?\
17         //              f=26&t=1053&sid=2a11c0f97306e4b699bf67502b7a754a
18         // CCID APDU, ISO 7816-4.
19
20         // Start with Select APDU:
21         // CLA INS P1 P2 Lc AID Le
22         //  00  A4 04 00                - GlobalPlatform - Application Select
23         // Lc = 07
24         //   A0 00 00 05 27
25         //      Yubico's RID (Registered application provider IDentifier)
26         //   20 01
27         //      PIX (Proprietary application Identifier eXtension)
28         //      for the Yubikey2 applet
29         // Le = 00
30         private static final byte[] selectApdu =
31                 {0x00, (byte) 0xA4, 0x04, 0x00, 0x07, (byte) 0xA0,
32                  0x00, 0x00, 0x05, 0x27, 0x20, 0x01, 0x00};
33
34         // Application APDUs:
35         // CLA INS P1 P2
36         //  00  01 YK 00
37         //   YK is the one-byte command&slot code as in the USB interface
38         //   Lc + data bytes follow
39         //   Le is optional
40         private static final byte SLOT_CHAL_HMAC1 = 0x30;
41         private static final byte SLOT_CHAL_HMAC2 = 0x38;
42
43         public static ArrayList<String> doChalResp(IsoDep isoTag, int slot,
44                                         ArrayList<String> cset)
45                         throws IOException, CRException {
46                 byte[] challenge = unhex(cset.get(0));
47                 if (challenge.length > 127) {
48                         throw new CRException(String.format(
49                         "NFC challenge size too big: %d",
50                         challenge.length));
51                 }
52                 if (slot != 1 && slot != 2) {
53                         throw new CRException(String.format(
54                         "NFC Yubikey slot is %d, can be 1 or 2",
55                         slot));
56                 }
57                 byte[] resp = isoTag.transceive(selectApdu);
58                 int length = resp.length;
59                 if (resp[length - 2] != (byte)0x90 ||
60                     resp[length - 1] != 0x00) {
61                         throw new CRException(String.format(
62                         "NFC select error code: %02x:%02x",
63                         resp[length - 2], resp[length - 1]));
64                 }
65                 byte[] crApdu = new byte[6+challenge.length];
66                 crApdu[0] = 0x00; // CLA
67                 crApdu[1] = 0x01; // INS
68                 switch (slot) {
69                 case 1: crApdu[2] = SLOT_CHAL_HMAC1; break; // P1
70                 case 2: crApdu[2] = SLOT_CHAL_HMAC2; break; // P1
71                 }
72                 crApdu[3] = 0x00; // P2
73                 crApdu[4] = (byte)challenge.length; // Lc
74                 System.arraycopy(challenge, 0, crApdu, 5,
75                                         challenge.length); // Payload
76                 crApdu[5+challenge.length] = 22; // Le
77                 resp = isoTag.transceive(crApdu);
78                 length = resp.length;
79                 if (resp[length - 2] != (byte)0x90 ||
80                     resp[length - 1] != 0x00) {
81                         throw new CRException(String.format(
82                         "NFC CR error code: %02x:%02x",
83                         resp[length - 2], resp[length - 1]));
84                 }
85                 if (length <= 2) {
86                         throw new CRException(String.format(
87                         "NFC wrong response size: only %d bytes",
88                         length-2));
89                 }
90                 ArrayList<String> rset = new ArrayList<String>();
91                 rset.add(hex(Arrays.copyOf(resp, length-2)));
92                 return rset;
93         }
94
95         private static String hex(byte[] a) {
96                 StringBuilder sb = new StringBuilder();
97                 if (a == null) return "<null>";
98                 for (byte b: a) sb.append(String.format("%02x", b&0xff));
99                 return sb.toString();
100         }
101
102         private static byte[] unhex(String s) {
103                 int len = s.length();
104                 if ((len % 2) != 0) return null;
105                 byte[] b = new byte[len / 2];
106                 for (int i = 0; i < len; i += 2) {
107                         b[i / 2] = (byte)Integer.parseInt(
108                                                 s.substring(i,i+2), 16);
109                 }
110                 return b;
111         }
112 }