Android app security is critical in 2026, with increasing threats and stricter privacy regulations. Protecting user data and your app from attacks is not optional—it’s essential for success on Google Play and user trust.

This comprehensive guide covers all aspects of Android app security, from basic best practices to advanced techniques.

Why Android App Security Matters

Key Reasons:

  • User Trust – Security breaches destroy reputation
  • Legal Compliance – GDPR, CCPA, and other regulations
  • Financial Loss – Data breaches cost millions
  • Play Store Requirements – Google enforces security standards
  • Competitive Advantage – Security is a feature

1. Secure Data Storage

Never Store Sensitive Data in Plain Text

Bad Practice:

// DON'T DO THIS
SharedPreferences prefs = getSharedPreferences("app", MODE_PRIVATE);
prefs.edit().putString("password", userPassword).apply();

Good Practice – Use EncryptedSharedPreferences:

MasterKey masterKey = new MasterKey.Builder(context)
    .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
    .build();

SharedPreferences securePrefs = EncryptedSharedPreferences.create(
    context,
    "secure_prefs",
    masterKey,
    EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
    EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
);

securePrefs.edit().putString("api_key", apiKey).apply();

Use Android Keystore

KeyGenerator keyGenerator = KeyGenerator.getInstance(
    KeyProperties.KEY_ALGORITHM_AES,
    "AndroidKeyStore"
);

KeyGenParameterSpec keyGenParameterSpec = new KeyGenParameterSpec.Builder(
    "MyKeyAlias",
    KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_DECRYPT
)
.setBlockModes(KeyProperties.BLOCK_MODE_GCM)
.setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
.build();

keyGenerator.init(keyGenParameterSpec);
SecretKey secretKey = keyGenerator.generateKey();

2. Network Security

Always Use HTTPS

Network Security Config (res/xml/network_security_config.xml):

<?xml version="1.0" encoding="utf-8"?>
<network-security-config>
    <base-config cleartextTrafficPermitted="false">
        <trust-anchors>
            <certificates src="system" />
        </trust-anchors>
    </base-config>
</network-security-config>

In AndroidManifest.xml:

<application
    android:networkSecurityConfig="@xml/network_security_config"
    ...>
</application>

Certificate Pinning

<network-security-config>
    <domain-config>
        <domain includeSubdomains="true">api.yourapp.com</domain>
        <pin-set>
            <pin digest="SHA-256">base64encodedpin==</pin>
            <pin digest="SHA-256">backuppin==</pin>
        </pin-set>
    </domain-config>
</network-security-config>

3. Authentication Best Practices

Use Biometric Authentication

BiometricPrompt biometricPrompt = new BiometricPrompt(
    activity,
    executor,
    new BiometricPrompt.AuthenticationCallback() {
        @Override
        public void onAuthenticationSucceeded(
            BiometricPrompt.AuthenticationResult result
        ) {
            // User authenticated successfully
        }

        @Override
        public void onAuthenticationFailed() {
            // Authentication failed
        }
    }
);

BiometricPrompt.PromptInfo promptInfo = new BiometricPrompt.PromptInfo.Builder()
    .setTitle("Biometric Authentication")
    .setSubtitle("Log in using your biometric credential")
    .setNegativeButtonText("Use password")
    .build();

biometricPrompt.authenticate(promptInfo);

Secure Token Storage

// Store tokens securely
EncryptedSharedPreferences.create(...)
    .edit()
    .putString("auth_token", token)
    .putLong("token_expiry", expiryTime)
    .apply();

// Always validate token expiry
long expiry = securePrefs.getLong("token_expiry", 0);
if (System.currentTimeMillis() > expiry) {
    // Token expired, re-authenticate
}

4. Code Obfuscation

Enable R8/ProGuard

android {
    buildTypes {
        release {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile(
                'proguard-android-optimize.txt'),
                'proguard-rules.pro'
        }
    }
}

Protect API Keys

Don’t hardcode API keys:

// BAD
String apiKey = "sk_live_1234567890abcdef";

Use BuildConfig or NDK:

// In build.gradle
buildTypes {
    release {
        buildConfigField "String", "API_KEY", ""${System.getenv('API_KEY')}""
    }
}

// In code
String apiKey = BuildConfig.API_KEY;

5. Input Validation

Validate All User Input

public boolean isValidEmail(String email) {
    if (email == null || email.isEmpty()) {
        return false;
    }
    
    String emailPattern = "[a-zA-Z0-9._-]+@[a-z]+\.+[a-z]+";
    return email.matches(emailPattern);
}

public boolean isValidPassword(String password) {
    // At least 8 characters, 1 uppercase, 1 lowercase, 1 digit
    String passwordPattern = "^(?=.*[a-z])(?=.*[A-Z])(?=.*\d).{8,}$";
    return password != null && password.matches(passwordPattern);
}

Prevent SQL Injection

// BAD - SQL Injection vulnerable
String query = "SELECT * FROM users WHERE username = '" + username + "'";

// GOOD - Use parameterized queries
String query = "SELECT * FROM users WHERE username = ?";
Cursor cursor = db.rawQuery(query, new String[]{username});

6. Permissions Best Practices

Request Minimum Permissions

<!-- Only request what you need -->
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.INTERNET" />

<!-- Avoid dangerous permissions if possible -->

Runtime Permission Handling

if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA)
    != PackageManager.PERMISSION_GRANTED) {
    
    ActivityCompat.requestPermissions(
        this,
        new String[]{Manifest.permission.CAMERA},
        CAMERA_PERMISSION_CODE
    );
} else {
    // Permission already granted
    openCamera();
}

7. Secure WebView Usage

WebView Security Settings

WebView webView = findViewById(R.id.webview);
WebSettings settings = webView.getSettings();

// Disable JavaScript if not needed
settings.setJavaScriptEnabled(false);

// Disable file access
settings.setAllowFileAccess(false);
settings.setAllowContentAccess(false);

// Enable safe browsing
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    settings.setSafeBrowsingEnabled(true);
}

// Only load HTTPS
webView.setWebViewClient(new WebViewClient() {
    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        return !url.startsWith("https://");
    }
});

8. Prevent Reverse Engineering

Techniques:

  • Code Obfuscation – R8/ProGuard
  • String Encryption – Encrypt sensitive strings
  • Root Detection – Detect rooted devices
  • Tamper Detection – Verify app integrity
  • Native Code – Move critical logic to NDK

Root Detection Example

public boolean isDeviceRooted() {
    // Check for su binary
    String[] paths = {
        "/system/app/Superuser.apk",
        "/sbin/su",
        "/system/bin/su",
        "/system/xbin/su"
    };
    
    for (String path : paths) {
        if (new File(path).exists()) {
            return true;
        }
    }
    
    return false;
}

9. Secure Logging

Never Log Sensitive Data

// BAD
Log.d("Auth", "Password: " + password);
Log.d("Payment", "Credit Card: " + cardNumber);

// GOOD
if (BuildConfig.DEBUG) {
    Log.d("Auth", "Login attempt for user: " + userId);
}

// Remove all logs in production
if (!BuildConfig.DEBUG) {
    // Disable logging
}

10. App Integrity Verification

Google Play Integrity API

IntegrityManager integrityManager = 
    IntegrityManagerFactory.create(context);

Task<IntegrityTokenResponse> integrityTokenResponse =
    integrityManager.requestIntegrityToken(
        IntegrityTokenRequest.builder()
            .setNonce(nonce)
            .build()
    );

integrityTokenResponse.addOnSuccessListener(response -> {
    String token = response.token();
    // Verify token on your server
});

Security Checklist

Before Release:

  1. ✅ Enable R8/ProGuard obfuscation
  2. ✅ Use HTTPS for all network calls
  3. ✅ Encrypt sensitive data at rest
  4. ✅ Implement certificate pinning
  5. ✅ Validate all user input
  6. ✅ Use EncryptedSharedPreferences
  7. ✅ Remove debug logs
  8. ✅ Request minimum permissions
  9. ✅ Secure WebView settings
  10. ✅ Implement biometric auth
  11. ✅ Test for common vulnerabilities
  12. ✅ Use Play Integrity API

Common Security Vulnerabilities

1. Insecure Data Storage

Risk: High
Fix: Use EncryptedSharedPreferences and Android Keystore

2. Weak Cryptography

Risk: High
Fix: Use AES-256, avoid MD5/SHA1

3. Insecure Communication

Risk: Critical
Fix: Always use HTTPS, implement certificate pinning

4. Improper Platform Usage

Risk: Medium
Fix: Follow Android security best practices

5. Code Tampering

Risk: Medium
Fix: Obfuscation, integrity checks

Security Testing Tools

  • MobSF – Mobile Security Framework
  • QARK – Quick Android Review Kit
  • Drozer – Android security assessment
  • Burp Suite – Network traffic analysis
  • APKTool – Reverse engineering

Best Practices Summary

  1. Encrypt everything – Data at rest and in transit
  2. Validate all input – Never trust user data
  3. Use HTTPS only – No cleartext traffic
  4. Obfuscate code – Make reverse engineering harder
  5. Minimize permissions – Request only what’s needed
  6. Secure authentication – Use biometrics and tokens
  7. Test regularly – Security is ongoing
  8. Stay updated – Follow security advisories

Conclusion

Android app security is not a one-time task—it’s an ongoing process. By implementing these best practices, you can significantly reduce security risks and protect your users’ data.

Start with the basics (HTTPS, encryption, input validation) and gradually implement advanced techniques. Regular security audits and staying updated with the latest threats are essential.

For more Android development tips, check out our free WebP converter tool.