Convert Surelock library to Kotlin

build.gradle

@@ -1,5 +1,5 @@
 buildscript {
-    ext.kotlin_version = '1.2.10'
+    ext.kotlin_version = '1.2.21'
     repositories {
         jcenter()
         maven {

surelock/build.gradle

@@ -1,12 +1,12 @@
 apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
 
 android {
-    compileSdkVersion 25
-    buildToolsVersion '25.0.1'
+    compileSdkVersion 27
 
     defaultConfig {
         minSdkVersion 15
-        targetSdkVersion 25
+        targetSdkVersion 27
         versionCode 1
         versionName "1.0"
     }
@@ -18,6 +18,10 @@ android {
 }
 
 dependencies {
-    compile 'com.android.support:appcompat-v7:25.3.1'
+    compile 'com.android.support:appcompat-v7:27.0.2'
     compile 'com.mattprecious.swirl:swirl:1.0.0'
+    compile "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+}
+repositories {
+    mavenCentral()
 }

surelock/src/main/java/com/smashingboxes/surelock/SharedPreferencesStorage.kt

@@ -0,0 +1,60 @@
+package com.smashingboxes.surelock
+
+import android.content.Context
+import android.content.SharedPreferences
+import android.util.Base64
+import java.util.*
+
+/**
+ * Created by Tyler McCraw on 3/5/17.
+ *
+ *
+ * Storage mechanism used by Surelock in order to
+ * persist encrypted objects in SharedPreferences by default
+ *
+ */
+
+class SharedPreferencesStorage
+/**
+ * Create a new SurelockStorage which uses SharedPreferences for persistence
+ *
+ * @param context context
+ * @param prefsName Desired preferences file.
+ */
+(private val context: Context, private val prefsName: String) : SurelockStorage {
+
+    private var preferences: SharedPreferences? = null
+
+    private val prefs: SharedPreferences
+        @Synchronized get() {
+            if (preferences == null) {
+                preferences = context.getSharedPreferences(prefsName, Context.MODE_PRIVATE)
+            }
+            return preferences!!
+        }
+
+    override fun createOrUpdate(key: String, objectToStore: ByteArray) {
+        val encodedString = Base64.encodeToString(objectToStore, Base64.DEFAULT)
+        prefs.edit().putString(key, encodedString).apply()
+    }
+
+    override fun get(key: String): ByteArray? {
+        val byteString = prefs.getString(key, null)
+        var decodedBytes: ByteArray? = null
+        if (!byteString.isNullOrEmpty()) {
+            decodedBytes = Base64.decode(byteString, Base64.DEFAULT)
+        }
+        return decodedBytes
+    }
+
+    override fun remove(key: String) {
+        prefs.edit().remove(key).apply()
+    }
+
+    override fun clearAll() {
+        prefs.edit().clear().apply()
+    }
+
+    override val keys: Set<String>?
+        get() = Collections.unmodifiableSet(LinkedHashSet(prefs.all.keys))
+}