diff --git a/src/Database/AuditLoggerBase.php b/src/Database/AuditLoggerBase.php
new file mode 100644
index 0000000..d8310fa
--- /dev/null
+++ b/src/Database/AuditLoggerBase.php
@@ -0,0 +1,74 @@
+<?php namespace SokoWeb\Database;
+
+use SokoWeb\Interfaces\Database\IConnection;
+
+abstract class AuditLoggerBase
+{
+    const LOG_TYPE_INSERT = 'insert';
+    const LOG_TYPE_UPDATE = 'update';
+    const LOG_TYPE_DELETE = 'delete';
+
+    private IConnection $connection;
+
+    private string $logTable;
+
+    public function __construct(IConnection $connection, string $logTable)
+    {
+        $this->connection = $connection;
+        $this->logTable = $logTable;
+    }
+
+    public function logInsert(string $localTable, $localId)
+    {
+        $data = [
+            'local_table' => $localTable,
+            'local_id' => $localId,
+            'type' => static::LOG_TYPE_INSERT,
+            'modifier_id' => $this->getModifierId(),
+        ];
+
+        $query = 'INSERT INTO ' . Utils::backtick($this->logTable) . ' SET ' . Utils::generateColumnsWithBinding(array_keys($data));
+        $stmt = $this->connection->prepare($query);
+        $stmt->execute($data);
+    }
+
+    public function logUpdate(string $localTable, $localId, array $diff)
+    {
+        $data = [
+            'local_table' => $localTable,
+            'local_id' => $localId,
+            'type' => static::LOG_TYPE_UPDATE,
+            'modifier_id' => $this->getModifierId(),
+            'column' => null,
+            'old' => null,
+            'new' => null,
+        ];
+
+        $query = 'INSERT INTO ' . Utils::backtick($this->logTable) . ' SET ' . Utils::generateColumnsWithBinding(array_keys($data));
+        $stmt = $this->connection->prepare($query);
+
+        foreach ($diff as $name => $values) {
+            $data['column'] = $name;
+            $data['old'] = $values['old'];
+            $data['new'] = $values['new'];
+            $stmt->execute($data);
+        }
+    }
+
+    public function logDelete(string $localTable, $localId, array $attributes)
+    {
+        $data = [
+            'local_table' => $localTable,
+            'local_id' => $localId,
+            'type' => static::LOG_TYPE_DELETE,
+            'modifier_id' => $this->getModifierId(),
+            'old' => $attributes,
+        ];
+
+        $query = 'INSERT INTO ' . Utils::backtick($this->logTable) . ' SET ' . Utils::generateColumnsWithBinding(array_keys($data));
+        $stmt = $this->connection->prepare($query);
+        $stmt->execute($data);
+    }
+
+    abstract protected function getModifierId();
+}
diff --git a/src/Database/Query/Modify.php b/src/Database/Query/Modify.php
index 1f554c8..fa5d7a4 100755
--- a/src/Database/Query/Modify.php
+++ b/src/Database/Query/Modify.php
@@ -2,6 +2,9 @@
 
 use SokoWeb\Interfaces\Database\IConnection;
 use SokoWeb\Database\Utils;
+use SokoWeb\Database\AuditLoggerBase;
+use SokoWeb\Interfaces\Database\IAuditLogger;
+use SokoWeb\Interfaces\Database\IResultSet;
 
 class Modify
 {
@@ -9,6 +12,8 @@ class Modify
 
     private string $table;
 
+    private ?AuditLoggerBase $auditLogger;
+
     private string $idName = 'id';
 
     private array $attributes = [];
@@ -17,10 +22,13 @@ class Modify
 
     private bool $autoIncrement = true;
 
-    public function __construct(IConnection $connection, string $table)
+    private ?array $diff = null;
+
+    public function __construct(IConnection $connection, string $table, ?AuditLoggerBase $auditLogger = null)
     {
         $this->connection = $connection;
         $this->table = $table;
+        $this->auditLogger = $auditLogger;
     }
 
     public function setIdName(string $idName): Modify
@@ -65,6 +73,13 @@ class Modify
         return $this;
     }
 
+    public function setDiff(array $diff): Modify
+    {
+        $this->diff = $diff;
+
+        return $this;
+    }
+
     public function getId()
     {
         return $this->attributes[$this->idName];
@@ -89,6 +104,10 @@ class Modify
 
         $stmt = $this->connection->prepare($query);
         $stmt->execute([$this->idName => $this->attributes[$this->idName]]);
+
+        if ($this->auditLogger !== null) {
+            $this->auditLogger->logDelete($this->attributes[$this->idName], $this->attributes);
+        }
     }
 
     private function insert(): void
@@ -99,7 +118,7 @@ class Modify
             $this->attributes[$this->idName] = $this->generateKey();
         }
 
-        $set = $this->generateColumnsWithBinding(array_keys($this->attributes));
+        $set = Utils::generateColumnsWithBinding(array_keys($this->attributes));
 
         $query = 'INSERT INTO ' . Utils::backtick($this->table) . ' SET ' . $set;
 
@@ -109,32 +128,60 @@ class Modify
         if ($this->autoIncrement) {
             $this->attributes[$this->idName] = $this->connection->lastId();
         }
+
+        if ($this->auditLogger !== null) {
+            $this->auditLogger->logInsert($this->attributes[$this->idName]);
+        }
     }
 
     private function update(): void
     {
+        $this->generateDiff();
+        if (count($this->diff) === 0) {
+            return;
+        }
+
         $attributes = $this->attributes;
         unset($attributes[$this->idName]);
 
-        $set = $this->generateColumnsWithBinding(array_keys($attributes));
+        $set = Utils::generateColumnsWithBinding(array_keys($attributes));
 
         $query = 'UPDATE ' . Utils::backtick($this->table) . ' SET ' . $set . ' WHERE ' . Utils::backtick($this->idName) . '=?';
 
         $stmt = $this->connection->prepare($query);
         $stmt->execute(array_merge($attributes, [$this->idName => $this->attributes[$this->idName]]));
-    }
 
-    public static function generateColumnsWithBinding(array $columns): string
-    {
-        array_walk($columns, function(&$value, $key) {
-            $value = Utils::backtick($value) . '=?';
-        });
-
-        return implode(',', $columns);
+        if ($this->auditLogger !== null) {
+            $this->auditLogger->logUpdate($this->attributes[$this->idName], $this->diff);
+        }
     }
 
     private function generateKey(): string
     {
         return substr(hash('sha256', serialize($this->attributes) . random_bytes(5) . microtime()), 0, 7);
     }
+
+    private function generateDiff(): void
+    {
+        if (isset($this->diff)) {
+            return;
+        }
+
+        $this->diff = [];
+        $original = $this->readFromDb(array_keys($this->attributes));
+        foreach ($original as $key => $value) {
+            if ($value !== $this->attributes[$key]) {
+                $this->diff[$key] = ['old' => $value, 'new' => $this->attributes[$key]];
+            }
+        }
+    }
+
+    private function readFromDb($columns): array
+    {
+        return (new Select($this->connection, $this->table))
+            ->columns($columns)
+            ->where($this->idName, '=', $this->attributes[$this->idName])
+            ->execute()
+            ->fetch(IResultSet::FETCH_ASSOC);
+    }
 }
diff --git a/src/Database/Utils.php b/src/Database/Utils.php
index 658b13c..c9c4885 100644
--- a/src/Database/Utils.php
+++ b/src/Database/Utils.php
@@ -5,4 +5,13 @@ class Utils {
     {
         return '`' . $name . '`';
     }
+
+    public static function generateColumnsWithBinding(array $columns): string
+    {
+        array_walk($columns, function(&$value, $key) {
+            $value = static::backtick($value) . '=?';
+        });
+
+        return implode(',', $columns);
+    }
 }
diff --git a/src/Interfaces/Database/IAuditLogger.php b/src/Interfaces/Database/IAuditLogger.php
new file mode 100644
index 0000000..e60d4cc
--- /dev/null
+++ b/src/Interfaces/Database/IAuditLogger.php
@@ -0,0 +1,10 @@
+<?php namespace SokoWeb\Interfaces\Database;
+
+interface IAuditLogger
+{
+    public function auditInsert(): void;
+
+    public function auditUpdate(): void;
+
+    public function auditDelete(): void;
+}
diff --git a/src/PersistentData/PersistentDataManager.php b/src/PersistentData/PersistentDataManager.php
index 627a783..b199548 100644
--- a/src/PersistentData/PersistentDataManager.php
+++ b/src/PersistentData/PersistentDataManager.php
@@ -121,15 +121,19 @@ class PersistentDataManager
 
         if ($id !== null) {
             $original = $model->getSnapshot();
+            $diff = [];
 
             foreach ($original as $key => $value) {
                 if ($value === $modified[$key]) {
                     unset($modified[$key]);
+                } else {
+                    $diff[$key] = ['old' => $value, 'new' => $modified[$key]];
                 }
             }
 
             if (count($modified) > 0) {
                 $modify->setId($id);
+                $modify->setDiff($original);
                 $modify->fill($modified);
                 $modify->save();
             }
diff --git a/src/Util/GoogleJwtValidator.php b/src/Util/GoogleJwtValidator.php
new file mode 100644
index 0000000..17901a5
--- /dev/null
+++ b/src/Util/GoogleJwtValidator.php
@@ -0,0 +1,102 @@
+<?php namespace RVR\Util;
+
+use SokoWeb\Http\Request;
+use SokoWeb\Interfaces\Http\IRequest;
+use phpseclib3\Math\BigInteger;
+use phpseclib3\Crypt\RSA;
+use Firebase\JWT\JWT;
+use Firebase\JWT\Key;
+
+class GoogleOAuth
+{
+    private static string $dialogUrlBase = 'https://accounts.google.com/o/oauth2/v2/auth';
+
+    private static string $tokenUrlBase = 'https://oauth2.googleapis.com/token';
+
+    private static string $certsUrl = 'https://www.googleapis.com/oauth2/v3/certs';
+
+    private IRequest $request;
+
+    public function __construct(IRequest $request)
+    {
+        $this->request = $request;
+    }
+
+    public function getDialogUrl(string $state, string $redirectUrl, ?string $nonce = null, ?string $loginHint = null): string
+    {
+        $oauthParams = [
+            'response_type' => 'code',
+            'client_id' => $_ENV['GOOGLE_OAUTH_CLIENT_ID'],
+            'scope' => 'openid email',
+            'redirect_uri' => $redirectUrl,
+            'state' => $state,
+        ];
+
+        if ($nonce !== null) {
+            $oauthParams['nonce'] = $nonce;
+        }
+
+        if ($loginHint !== null) {
+            $oauthParams['login_hint'] = $loginHint;
+        }
+
+        return self::$dialogUrlBase . '?' . http_build_query($oauthParams);
+    }
+
+    public function getToken(string $code, string $redirectUrl): array
+    {
+        $tokenParams = [
+            'code' => $code,
+            'client_id' => $_ENV['GOOGLE_OAUTH_CLIENT_ID'],
+            'client_secret' => $_ENV['GOOGLE_OAUTH_CLIENT_SECRET'],
+            'redirect_uri' => $redirectUrl,
+            'grant_type' => 'authorization_code',
+        ];
+
+        $this->request->setUrl(self::$tokenUrlBase);
+        $this->request->setMethod(IRequest::HTTP_POST);
+        $this->request->setQuery($tokenParams);
+        $response = $this->request->send();
+
+        return json_decode($response->getBody(), true);
+    }
+
+    public function validateJwt($jwt): ?array
+    {
+        $request = new Request(self::$certsUrl, IRequest::HTTP_GET);
+        $response = $request->send();
+        $certs = json_decode($response->getBody(), true)['keys'];
+
+        foreach ($certs as $cert) {
+            $publicKey = $this->getPublicKey($cert);
+
+            try {
+                return (array) JWT::decode($jwt, new Key($publicKey, 'RS256'));
+            } catch (ExpiredException $e) {
+                return null;
+            } catch (SignatureInvalidException $e) {
+                //continue
+            } catch (DomainException $e) {
+                //continue
+            }
+        }
+
+        return null;
+    }
+
+    private function getPublicKey($cert): string
+    {
+        $modulus = new BigInteger($this->base64Decode($cert['n']), 256);
+        $exponent = new BigInteger($this->base64Decode($cert['e']), 256);
+        $component = ['n' => $modulus, 'e' => $exponent];
+        $rsa = new RSA();
+        $rsa->loadKey($component);
+        return $rsa->getPublicKey();
+    }
+
+    private function base64Decode($input): string
+    {
+        $input = str_replace(['_', '-'], ['/', '+'], $input);
+        return base64_decode($input);
+    }
+}