Add a class with our hueristics to check if a device was updated

Author: Fuzion24

app/src/main/java/fuzion24/device/vulnerability/vulnerabilities/helper/DeviceUpdateChecker.java

@@ -0,0 +1,57 @@
+package fuzion24.device.vulnerability.vulnerabilities.helper;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.os.Build;
+import android.util.Base64;
+
+import java.io.File;
+import java.security.MessageDigest;
+import java.util.HashSet;
+import java.util.Scanner;
+
+import fuzion24.device.vulnerability.util.SharedPreferencesUtils;
+
+/**
+ * Created by fuzion24 on 12/4/15.
+ */
+public class DeviceUpdateChecker {
+    public static boolean wasDeviceUpdated(Context ctx){
+
+        /*
+            Take a hash of the build.prop and /proc/version
+            If this changes, assume the device has been updated
+        */
+        String buildPropFile = readFile("/system/build.prop");
+        String procVersion   = readFile("/proc/version");
+
+        String fingerprint = hashString(buildPropFile + procVersion);
+        String lastFingerprint = SharedPreferencesUtils.getBuildUpdateFingerprint(ctx);
+        if(fingerprint.equals(lastFingerprint)){
+            return false;
+        } else {
+            SharedPreferencesUtils.setBuildUpdateFingerPrint(ctx, fingerprint);
+            return true;
+        }
+    }
+
+    private static String hashString(String data){
+        try {
+            MessageDigest md = MessageDigest.getInstance("SHA");
+            md.update(data.getBytes());
+            byte[] hash = md.digest();
+            return Base64.encodeToString(hash, Base64.DEFAULT);
+        } catch (Exception e) {
+            return "";
+        }
+    }
+
+    private static String readFile(String filename){
+        try {
+            return new Scanner(new File(filename)).useDelimiter("\\Z").next();
+        }catch(Exception e){
+            return "";
+        }
+    }
+
+}