Create a simple Android app that uses Encrypted Preferences with a Singleton architecture

Creating a simple Android app that uses Encrypted Preferences with a Singleton architecture involves several steps. Below is a guide to help you set up this app. We'll use Kotlin for this example.

Step 1: Set Up Your Android Project

1. Open Android Studio and create a new project.
2. Select an Empty Activity template.
3. Name your project and choose Kotlin as the programming language.

Step 2: Add Dependencies

In your build.gradle (app level), add the dependencies for Encrypted Preferences:

dependencies {

    implementation 'androidx.security:security-crypto:1.1.0-alpha03'

    // Other dependencies

}

Step 3: Create the EncryptedPreferencesManager Singleton

Create a Kotlin file EncryptedPreferencesManager.kt in a suitable package (e.g., com.example.myapp).

package com.example.myapp

import android.content.Context

import androidx.security.crypto.EncryptedSharedPreferences

import androidx.security.crypto.MasterKeys

class EncryptedPreferencesManager private constructor(context: Context) {

    private val sharedPreferences = EncryptedSharedPreferences.create(

        "my_encrypted_prefs",

        MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC),

        context,

        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,

        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM

    )

    companion object {

        @Volatile private var INSTANCE: EncryptedPreferencesManager? = null

        fun getInstance(context: Context): EncryptedPreferencesManager {

            return INSTANCE ?: synchronized(this) {

                INSTANCE ?: EncryptedPreferencesManager(context).also { INSTANCE = it }

            }

        }

    }

    fun putString(key: String, value: String) {

        sharedPreferences.edit().putString(key, value).apply()

    }

    fun getString(key: String, defaultValue: String? = null): String? {

        return sharedPreferences.getString(key, defaultValue)

    }

    // Add other methods as needed

}

Step 4: Use EncryptedPreferencesManager in Your Activity

In your MainActivity.kt, you can use the EncryptedPreferencesManager to save and retrieve encrypted preferences.

package com.example.myapp

import android.os.Bundle

import androidx.appcompat.app.AppCompatActivity

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)

        val encryptedPreferences = EncryptedPreferencesManager.getInstance(this)

        // Save a value

        encryptedPreferences.putString("example_key", "example_value")

        // Retrieve a value

        val value = encryptedPreferences.getString("example_key")

        println("Retrieved value: $value")

    }

}