add barely functional nfc intent activity (WIP!)

1 files changed, 312 insertions, 0 deletions

diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/NfcIntentActivity.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/NfcIntentActivity.java
new file mode 100644
index 000000000..cb15dbec2
--- /dev/null
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/NfcIntentActivity.java
@@ -0,0 +1,312 @@
+/**
+ * Copyright (c) 2013-2014 Philipp Jakubeit, Signe Rüsch, Dominik Schürmann
+ *
+ * Licensed under the Bouncy Castle License (MIT license). See LICENSE file for details.
+ */
+
+package org.sufficientlysecure.keychain.ui;
+
+import android.annotation.TargetApi;
+import android.app.PendingIntent;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.nfc.NfcAdapter;
+import android.nfc.Tag;
+import android.nfc.tech.IsoDep;
+import android.os.Build;
+import android.os.Bundle;
+import android.support.v7.app.ActionBarActivity;
+import android.view.WindowManager;
+import android.widget.Toast;
+
+import org.spongycastle.util.encoders.Hex;
+import org.sufficientlysecure.keychain.Constants;
+import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.util.Iso7816TLV;
+import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
+import org.sufficientlysecure.keychain.util.Log;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+/**
+ * This class provides a communication interface to OpenPGP applications on ISO SmartCard compliant
+ * NFC devices.
+ *
+ * For the full specs, see http://g10code.com/docs/openpgp-card-2.0.pdf
+ */
+@TargetApi(Build.VERSION_CODES.GINGERBREAD_MR1)
+public class NfcIntentActivity extends ActionBarActivity {
+
+    // special extra for OpenPgpService
+    public static final String EXTRA_DATA = "data";
+
+    private Intent mServiceIntent;
+
+    private static final int TIMEOUT = 100000;
+
+    private NfcAdapter mNfcAdapter;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        Log.d(Constants.TAG, "NfcActivity.onCreate");
+
+        getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
+
+        setContentView(R.layout.nfc_activity);
+
+        Intent intent = getIntent();
+        Bundle data = intent.getExtras();
+        String action = intent.getAction();
+
+        Log.d(Constants.TAG, action);
+        Log.d(Constants.TAG, intent.getDataString());
+
+        // TODO check fingerprint
+        // mFingerprint = data.getByteArray(EXTRA_FINGERPRINT);
+
+        if (!NfcAdapter.ACTION_NDEF_DISCOVERED.equals(action)) {
+            Log.d(Constants.TAG, "Action not supported: " + action);
+            finish();
+        }
+
+        try {
+            Tag detectedTag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
+
+            // Connect to the detected tag, setting a couple of settings
+            IsoDep isoDep = IsoDep.get(detectedTag);
+            isoDep.setTimeout(TIMEOUT); // timeout is set to 100 seconds to avoid cancellation during calculation
+            isoDep.connect();
+
+            nfcGreet(isoDep);
+            // nfcPin(isoDep, "yoloswag");
+            nfcGetFingerprint(isoDep);
+
+        } catch (IOException e) {
+            Log.e(Constants.TAG, "IOException!", e);
+            finish();
+        }
+
+    }
+
+    /**
+     * Called when the system is about to start resuming a previous activity,
+     * disables NFC Foreground Dispatch
+     */
+    public void onPause() {
+        super.onPause();
+        Log.d(Constants.TAG, "NfcActivity.onPause");
+
+        // disableNfcForegroundDispatch();
+    }
+
+    /**
+     * Called when the activity will start interacting with the user,
+     * enables NFC Foreground Dispatch
+     */
+    public void onResume() {
+        super.onResume();
+        Log.d(Constants.TAG, "NfcActivity.onResume");
+
+        // enableNfcForegroundDispatch();
+    }
+
+    /** Handle NFC communication and return a result.
+     *
+     * This method is called by onNewIntent above upon discovery of an NFC tag.
+     * It handles initialization and login to the application, subsequently
+     * calls either nfcCalculateSignature() or nfcDecryptSessionKey(), then
+     * finishes the activity with an appropiate result.
+     *
+     * On general communication, see also
+     * http://www.cardwerk.com/smartcards/smartcard_standard_ISO7816-4_annex-a.aspx
+     *
+     * References to pages are generally related to the OpenPGP Application
+     * on ISO SmartCard Systems specification.
+     *
+     */
+    private void nfcGreet(IsoDep isoDep) throws IOException {
+
+        // SW1/2 0x9000 is the generic "ok" response, which we expect most of the time.
+        // See specification, page 51
+        String accepted = "9000";
+
+        // Command APDU (page 51) for SELECT FILE command (page 29)
+        String opening =
+                "00" // CLA
+                        + "A4" // INS
+                        + "04" // P1
+                        + "00" // P2
+                        + "06" // Lc (number of bytes)
+                        + "D27600012401" // Data (6 bytes)
+                        + "00"; // Le
+        if (!card(isoDep, opening).equals(accepted)) { // activate connection
+            toast("Opening Error!");
+            setResult(RESULT_CANCELED, mServiceIntent);
+            finish();
+        }
+    }
+
+    private void nfcPin(IsoDep isoDep, String pin) throws IOException {
+
+        String data = "00CA006E00";
+        String fingerprint = card(isoDep, data);
+
+        // Command APDU for VERIFY command (page 32)
+        String login =
+              "00" // CLA
+            + "20" // INS
+            + "00" // P1
+            + "82" // P2 (PW1)
+            + String.format("%02x", pin.length()) // Lc
+            + Hex.toHexString(pin.getBytes());
+        if ( ! card(isoDep, login).equals("9000")) { // login
+            toast("Pin Error!");
+            setResult(RESULT_CANCELED, mServiceIntent);
+            finish();
+        }
+
+    }
+
+    /**
+     * Gets the user ID
+     *
+     * @return the user id as "name <email>"
+     * @throws java.io.IOException
+     */
+    public static String getUserId(IsoDep isoDep) throws IOException {
+        String info = "00CA006500";
+        String data = "00CA005E00";
+        return getName(card(isoDep, info)) + " <" + (new String(Hex.decode(getDataField(card(isoDep, data))))) + ">";
+    }
+
+    /**
+     * Gets the long key ID
+     *
+     * @return the long key id (last 16 bytes of the fingerprint)
+     * @throws java.io.IOException
+     */
+    public static long getKeyId(IsoDep isoDep) throws IOException {
+        String keyId = nfcGetFingerprint(isoDep).substring(24);
+        Log.d(Constants.TAG, "keyId: " + keyId);
+        return Long.parseLong(keyId, 16);
+    }
+
+    /**
+     * Gets the fingerprint of the signature key
+     *
+     * @return the fingerprint
+     * @throws java.io.IOException
+     */
+    public static String nfcGetFingerprint(IsoDep isoDep) throws IOException {
+        String data = "00CA006E00";
+        byte[] buf = isoDep.transceive(Hex.decode(data));
+
+        Iso7816TLV tlv = Iso7816TLV.readSingle(buf, true);
+        Log.d(Constants.TAG, "nfc tlv data:\n" + tlv.prettyPrint());
+
+        Iso7816TLV fptlv = Iso7816TLV.findRecursive(tlv, 0xc5);
+        if (fptlv != null) {
+            ByteBuffer fpbuf = ByteBuffer.wrap(fptlv.mV);
+            byte[] fp = new byte[20];
+            fpbuf.get(fp);
+            Log.d(Constants.TAG, "fingerprint 1: " + KeyFormattingUtils.convertFingerprintToHex(fp));
+            fpbuf.get(fp);
+            Log.d(Constants.TAG, "fingerprint 2: " + KeyFormattingUtils.convertFingerprintToHex(fp));
+            fpbuf.get(fp);
+            Log.d(Constants.TAG, "fingerprint 3: " + KeyFormattingUtils.convertFingerprintToHex(fp));
+        }
+
+        return "nope";
+    }
+
+    /**
+     * Prints a message to the screen
+     *
+     * @param text the text which should be contained within the toast
+     */
+    private void toast(String text) {
+        Toast.makeText(this, text, Toast.LENGTH_LONG).show();
+    }
+
+    /**
+     * Receive new NFC Intents to this activity only by enabling foreground dispatch.
+     * This can only be done in onResume!
+     */
+    public void enableNfcForegroundDispatch() {
+        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
+        Intent nfcI = new Intent(this, NfcIntentActivity.class)
+                .addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP);
+        PendingIntent nfcPendingIntent = PendingIntent.getActivity(this, 0, nfcI, 0);
+        IntentFilter[] writeTagFilters = new IntentFilter[]{
+                new IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED)
+        };
+
+        // https://code.google.com/p/android/issues/detail?id=62918
+        // maybe mNfcAdapter.enableReaderMode(); ?
+        try {
+            mNfcAdapter.enableForegroundDispatch(this, nfcPendingIntent, writeTagFilters, null);
+        } catch (IllegalStateException e) {
+            Log.i(Constants.TAG, "NfcForegroundDispatch Error!", e);
+        }
+        Log.d(Constants.TAG, "NfcForegroundDispatch has been enabled!");
+    }
+
+    /**
+     * Disable foreground dispatch in onPause!
+     */
+    public void disableNfcForegroundDispatch() {
+        mNfcAdapter.disableForegroundDispatch(this);
+        Log.d(Constants.TAG, "NfcForegroundDispatch has been disabled!");
+    }
+
+    /**
+     * Gets the name of the user out of the raw card output regarding card holder related data
+     *
+     * @param name the raw card holder related data from the card
+     * @return the name given in this data
+     */
+    public static  String getName(String name) {
+        String slength;
+        int ilength;
+        name = name.substring(6);
+        slength = name.substring(0, 2);
+        ilength = Integer.parseInt(slength, 16) * 2;
+        name = name.substring(2, ilength + 2);
+        name = (new String(Hex.decode(name))).replace('<', ' ');
+        return (name);
+    }
+
+    /**
+     * Reduces the raw data from the card by four characters
+     *
+     * @param output the raw data from the card
+     * @return the data field of that data
+     */
+    private static String getDataField(String output) {
+        return output.substring(0, output.length() - 4);
+    }
+
+    /**
+     * Communicates with the OpenPgpCard via the APDU
+     *
+     * @param hex the hexadecimal APDU
+     * @return The answer from the card
+     * @throws java.io.IOException throws an exception if something goes wrong
+     */
+    public static String card(IsoDep isoDep, String hex) throws IOException {
+        return getHex(isoDep.transceive(Hex.decode(hex)));
+    }
+
+    /**
+     * Converts a byte array into an hex string
+     *
+     * @param raw the byte array representation
+     * @return the  hexadecimal string representation
+     */
+    public static String getHex(byte[] raw) {
+        return new String(Hex.encode(raw));
+    }
+
+}