java - 从智能手机捕获指纹并保存到文件

Question

我正在做一个项目，我需要使用 NFC 连接将指纹扫描捕获的结果传输到本地服务器，然后从服务器接收答复。

到目前为止，我设法了解如何使用谷歌的 API 进行传输和扫描指纹，但问题是我无法获取扫描结果以将其发送给服务器以完成身份验证。

我正在使用来自 API23 的谷歌指纹库。

主要 Activity :

package com.gmtechnology.smartalarm;

import android.Manifest;
import android.app.KeyguardManager;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.hardware.fingerprint.FingerprintManager;
import android.net.Uri;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.Settings;
import android.security.keystore.KeyGenParameterSpec;
import android.security.keystore.KeyPermanentlyInvalidatedException;
import android.security.keystore.KeyProperties;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.NavigationView;
import android.support.v4.app.ActivityCompat;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.UnrecoverableKeyException;
import java.security.cert.CertificateException;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;


public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

private static final String KEY_NAME = "main_key";
protected FingerprintManager fingerprintManager;
protected KeyguardManager keyguardManager;
private KeyStore keyStore;
protected KeyGenerator keyGenerator;
private Cipher cipher;
protected FingerprintManager.CryptoObject cryptoObject;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    TextView state = (TextView) findViewById(R.id.state);

    FloatingActionButton lock = (FloatingActionButton) findViewById(R.id.lock);
    FloatingActionButton unlock = (FloatingActionButton) findViewById(R.id.unlock);
    FloatingActionButton start = (FloatingActionButton) findViewById(R.id.start);
    FloatingActionButton stop = (FloatingActionButton) findViewById(R.id.stop);

    PackageManager pm = this.getPackageManager();
    // Check whether NFC is available on device
    if (!pm.hasSystemFeature(PackageManager.FEATURE_NFC)) {
        // NFC is not available on the device.
        Toast.makeText(this, "The device does not has NFC hardware",
                Toast.LENGTH_SHORT).show();
    }
    // Check whether device is running Android 4.1 or higher
    else if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
        // Android Beam feature is not supported.
        Toast.makeText(this, "Wrong android version",
                Toast.LENGTH_SHORT).show();
    }

    keyguardManager =
            (KeyguardManager) getSystemService(KEYGUARD_SERVICE);
    fingerprintManager =
            (FingerprintManager) getSystemService(FINGERPRINT_SERVICE);

    if (!keyguardManager.isKeyguardSecure()) {

        Toast.makeText(this,
                "Lock screen security not enabled in Settings",
                Toast.LENGTH_LONG).show();
        return;
    }

    if (ActivityCompat.checkSelfPermission(this,
            Manifest.permission.USE_FINGERPRINT) !=
            PackageManager.PERMISSION_GRANTED) {
        Toast.makeText(this,
                "Fingerprint authentication permission not enabled",
                Toast.LENGTH_LONG).show();

        return;
    }

    if (!fingerprintManager.hasEnrolledFingerprints()) {

        // This happens when no fingerprints are registered.
        Toast.makeText(this,
                "Register at least one fingerprint in Settings",
                Toast.LENGTH_LONG).show();
        return;
    }

    generateKey();

    if (cipherInit()) {
        cryptoObject = new FingerprintManager.CryptoObject(cipher);
        //cryptoObject == the scanned fingerprint
        FingerprintHandler helper = new FingerprintHandler(this);
        helper.startAuth(fingerprintManager, cryptoObject, lock, unlock, start, stop, state);
    }

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    state(1, lock, unlock, start, stop, state);
}

public void sendFile(View view) {
    NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(this);

    String command = "command";

    if(!nfcAdapter.isEnabled()){

        Toast.makeText(this, "Please enable NFC.",
                Toast.LENGTH_SHORT).show();
        startActivity(new Intent(Settings.ACTION_NFC_SETTINGS));
    }

    else if(!nfcAdapter.isNdefPushEnabled()) {

        Toast.makeText(this, "Please enable Android Beam.",
                Toast.LENGTH_SHORT).show();
        startActivity(new Intent(Settings.ACTION_NFCSHARING_SETTINGS));
    }

    else {

        if(view.getId() == R.id.lock) {

            command = "lock";

        }

        else if(view.getId() == R.id.unlock) {

            command = "unlock";

        }

        else if(view.getId() == R.id.start) {

            command = "start";

        }

        else if(view.getId() == R.id.stop) {

            command = "stop";

        }

        NdefRecord ndefRecord = NdefRecord.createMime("text/plain", command.getBytes());
        NdefMessage ndefMessage = new NdefMessage(ndefRecord);

        String fileName = "wallpaper.png";

        // Retrieve the path to the user's public pictures directory
        File fileDirectory = Environment
                .getExternalStoragePublicDirectory(
                        Environment.DIRECTORY_PICTURES);

        // Create a new file using the specified directory and name
        File fileToTransfer = new File(fileDirectory, fileName);
        fileToTransfer.setReadable(true, false);

        nfcAdapter.setBeamPushUris(
                new Uri[]{Uri.fromFile(fileToTransfer)}, this);
        nfcAdapter.setNdefPushMessage(ndefMessage, this);
    }
}

protected void generateKey() {
    try {
        keyStore = KeyStore.getInstance("AndroidKeyStore");
    } catch (Exception e) {
        e.printStackTrace();
    }

    try {
        keyGenerator = KeyGenerator.getInstance(
                KeyProperties.KEY_ALGORITHM_AES,
                "AndroidKeyStore");
    } catch (NoSuchAlgorithmException |
            NoSuchProviderException e) {
        throw new RuntimeException(
                "Failed to get KeyGenerator instance", e);
    }

    try {
        keyStore.load(null);
        keyGenerator.init(new
                KeyGenParameterSpec.Builder(KEY_NAME,
                KeyProperties.PURPOSE_ENCRYPT |
                        KeyProperties.PURPOSE_DECRYPT)
                .setBlockModes(KeyProperties.BLOCK_MODE_CBC)
                .setUserAuthenticationRequired(true)
                .setEncryptionPaddings(
                        KeyProperties.ENCRYPTION_PADDING_PKCS7)
                .build());
        keyGenerator.generateKey();
    } catch (NoSuchAlgorithmException |
            InvalidAlgorithmParameterException
            | CertificateException | IOException e) {
        throw new RuntimeException(e);
    }
}

public boolean cipherInit() {
    try {
        cipher = Cipher.getInstance(
                KeyProperties.KEY_ALGORITHM_AES + "/"
                        + KeyProperties.BLOCK_MODE_CBC + "/"
                        + KeyProperties.ENCRYPTION_PADDING_PKCS7);
    } catch (NoSuchAlgorithmException |
            NoSuchPaddingException e) {
        throw new RuntimeException("Failed to get Cipher", e);
    }

    try {
        keyStore.load(null);
        SecretKey key = (SecretKey) keyStore.getKey(KEY_NAME,
                null);
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return true;
    } catch (KeyPermanentlyInvalidatedException e) {
        return false;
    } catch (KeyStoreException | CertificateException
            | UnrecoverableKeyException | IOException
            | NoSuchAlgorithmException | InvalidKeyException e) {
        throw new RuntimeException("Failed to init Cipher", e);
    }
}


@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_camera) {
        // Handle the camera action
    } else if (id == R.id.nav_gallery) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}


public void state (int s, FloatingActionButton lock, FloatingActionButton unlock, FloatingActionButton start, FloatingActionButton stop, TextView state) {

    if (s == 1) {
        state.setText(R.string.scan);
        state.setTextColor(0xFF970E0E);
        lock.setEnabled(false);
        lock.hide();
        unlock.setEnabled(false);
        unlock.hide();
        start.setEnabled(false);
        start.hide();
        stop.setEnabled(false);
        stop.hide();
    }

    if (s == 2) {
        state.setText(R.string.done);
        state.setTextColor(0xFF149926);
        lock.setEnabled(true);
        lock.show();
        unlock.setEnabled(true);
        unlock.show();
        start.setEnabled(true);
        start.show();
        stop.setEnabled(true);
        stop.show();
    }

    if (s == 3) {
        state.setText(R.string.error);
        state.setTextColor(0xFF970E0E);
        lock.setEnabled(false);
        lock.hide();
        unlock.setEnabled(false);
        unlock.hide();
        start.setEnabled(false);
        start.hide();
        stop.setEnabled(false);
        stop.hide();
    }
}
}

指纹处理器:

package com.gmtechnology.smartalarm;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.fingerprint.FingerprintManager;
import android.os.CancellationSignal;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.ActivityCompat;
import android.widget.TextView;

public class FingerprintHandler extends
    FingerprintManager.AuthenticationCallback {

protected CancellationSignal cancellationSignal;
private Context appContext;


private FloatingActionButton mlock;
private FloatingActionButton mstart;
private FloatingActionButton munlock;
private FloatingActionButton mstop;
private TextView mstate;


public FingerprintHandler(Context context) {
    appContext = context;
}

public void startAuth(FingerprintManager manager,
                      FingerprintManager.CryptoObject cryptoObject, FloatingActionButton lock, FloatingActionButton unlock, FloatingActionButton start, FloatingActionButton stop, TextView state) {

    mlock = lock;
    munlock = unlock;
    mstart = start;
    mstop = stop;
    mstate = state;

    cancellationSignal = new CancellationSignal();

    if (ActivityCompat.checkSelfPermission(appContext,
            Manifest.permission.USE_FINGERPRINT) !=
            PackageManager.PERMISSION_GRANTED) {
        return;
    }
    manager.authenticate(cryptoObject, cancellationSignal, 0, this, null);
}

@Override
public void onAuthenticationHelp(int helpMsgId,
                                 CharSequence helpString) {

    new MainActivity().state(3, mlock, munlock, mstart, mstop, mstate);
}

@Override
public void onAuthenticationFailed() {

    new MainActivity().state(3, mlock, munlock, mstart, mstop, mstate);
}

@Override
public void onAuthenticationSucceeded(
        FingerprintManager.AuthenticationResult result) {

    new MainActivity().state(2, mlock, munlock, mstart, mstop, mstate);
}
}

如果有人能指出我如何捕获扫描结果并将其转换为可以通过 NFC 发送的格式，那就太棒了!

PS:我不是程序员，请放过我T^T

根据 Micheal 的回答重申可能性: 有没有办法直接使用NFC将传感器连接到服务器，这样数据就可以直接发送到服务器进行身份验证而不保存？整个想法是认证是由外部服务器而不是智能手机完成的，这样就使智能手机成为“通用 key ”，因此任何智能手机都可以用于对任何服务器进行认证，当然使用正确的应用程序，或者也许以某种方式诱使智能手机使用通过 NFC 连接的数据库来比较指纹，这样当前信息就在安全内存中，但用于比较指纹的数据库在远程服务器上。我知道这些听起来很棘手，甚至可能是“疯狂的”，但如果有可能在“适当”的方式之外做到这一点，那就足够了，那只是为了研究和研究计划。

Answer 1

Android 指纹认证是专门设计的，无法为所欲为。

该设计确保指纹图像数据在 Android 操作系统中永远不可用根本。即使您对设备进行 root 操作或破坏内核，这些数据也根本不可用。指纹图像需要从指纹扫描仪安全地传递到进行指纹匹配的安全硬件。这实际上是 Android 合规性要求。原因是指纹是重要的个人信息，不能泄露。

关于您的备选建议，我无法想象为什么任何制造商都能做到这一点。

如果你想使用 Android 作为通用 key ，你应该这样做:

1. 使用 AndroidKeyStore(我推荐 EC)在设备上生成公钥/私钥对，指定 key 只能用于指纹验证。
2. 提取公钥并向服务器注册。
3. 要使用您的通用 key “解锁”，请与服务器执行质询-响应协议(protocol)，例如:
   1. 在服务器上生成一个随机值，比如 32 字节。
   2. 将随机值发送到手机。
   3. 使用您的 AndroidKeyStore key 创建一个 Signature 对象，对其进行初始化并将其包装在 FingerprintManager.CryptoObject 中。
   4. 进行指纹认证，完成后对随机值进行签名。
   5. 将签名的随机值发送到服务器。
   6. 让服务器验证随机值和签名。

如果您想在服务器上进行指纹验证，您需要使用其他类型的指纹扫描仪。您无法使用 Android(或 iOS)手机执行此操作。