diff --git a/app/Http/Requests/BalanceSummaryRequest.php b/app/Http/Requests/BalanceSummaryRequest.php
index 6835df2..0e7a9f2 100644
--- a/app/Http/Requests/BalanceSummaryRequest.php
+++ b/app/Http/Requests/BalanceSummaryRequest.php
@@ -102,8 +102,10 @@ class BalanceSummaryRequest extends FormRequest
             'account_number' => [
                 'required',
                 'string',
-                'max:50',
-                'regex:/^[A-Z0-9-]+$/i'  // Hanya alphanumeric dan dash
+                'max:10',
+                'min:10',
+                'exists:account_balances,account_number',
+                'regex:/^[0-9]+$/'  // Numeric only
             ],
             'start_date' => [
                 'required',
@@ -130,16 +132,19 @@ class BalanceSummaryRequest extends FormRequest
     public function messages(): array
     {
         return [
+            'account_number.exists'      => 'Nomor rekening tidak ditemukan.',
             'account_number.required'    => 'Nomor rekening wajib diisi.',
             'account_number.string'      => 'Nomor rekening harus berupa teks.',
             'account_number.max'         => 'Nomor rekening maksimal :max karakter.',
-            'account_number.regex'       => 'Nomor rekening hanya boleh mengandung huruf, angka, dan strip.',
+            'account_number.min'         => 'Nomor rekening minimal :min karakter.',
+            'account_number.regex'       => 'Nomor rekening hanya boleh mengandung angka.',
             'start_date.required'        => 'Tanggal awal wajib diisi.',
             'start_date.date_format'     => 'Format tanggal awal harus YYYY-MM-DD.',
             'start_date.before_or_equal' => 'Tanggal awal harus sebelum atau sama dengan tanggal akhir.',
             'end_date.required'          => 'Tanggal akhir wajib diisi.',
             'end_date.date_format'       => 'Format tanggal akhir harus YYYY-MM-DD.',
             'end_date.after_or_equal'    => 'Tanggal akhir harus sesudah atau sama dengan tanggal awal.',
+            'end_date.before_or_equal'   => 'Tanggal akhir harus sebelum atau sama dengan hari ini.',
         ];
     }
 
@@ -155,6 +160,18 @@ class BalanceSummaryRequest extends FormRequest
     {
         $errors = $validator->errors();
 
+        if($errors->has('account_number') && $errors->first('account_number') === 'Nomor rekening tidak ditemukan.') {
+            throw new HttpResponseException(
+                response()->json(
+                    ResponseCode::ACCOUNT_NOT_FOUND->toResponse(
+                        null,
+                        'Nomor rekening tidak ditemukan'
+                    ),
+                    ResponseCode::ACCOUNT_NOT_FOUND->getHttpStatus()
+                )
+            );
+        }
+
         throw new HttpResponseException(
             response()->json(
                 ResponseCode::INVALID_FIELD->toResponse(
@@ -176,8 +193,89 @@ class BalanceSummaryRequest extends FormRequest
     protected function failedAuthorization()
     {
         $xApiKey = $this->header('X-Api-Key');
+        $xSignature = $this->header('X-Signature');
+        $xTimestamp = $this->header('X-Timestamp');
+
         $expectedApiKey = config('webstatement.api_key');
 
+        if(!$xApiKey){
+            throw new HttpResponseException(
+                response()->json(
+                    ResponseCode::INVALID_FIELD->toResponse(
+                        ['errors' => ['X-Api-Key' => 'API Key wajib diisi']],
+                        'Validasi gagal'
+                    ),
+                    ResponseCode::INVALID_FIELD->getHttpStatus()
+                )
+            );
+        }
+
+        if(!$xSignature){
+            throw new HttpResponseException(
+                response()->json(
+                    ResponseCode::INVALID_FIELD->toResponse(
+                        ['errors' => ['X-Signature' => 'Signature wajib diisi']],
+                        'Validasi gagal'
+                    ),
+                    ResponseCode::INVALID_FIELD->getHttpStatus()
+                )
+            );
+        }
+
+        if(!$xTimestamp){
+            throw new HttpResponseException(
+                response()->json(
+                    ResponseCode::INVALID_FIELD->toResponse(
+                        ['errors' => ['X-Timestamp' => 'Timestamp wajib diisi']],
+                        'Validasi gagal'
+                    ),
+                    ResponseCode::INVALID_FIELD->getHttpStatus()
+                )
+            );
+        }
+
+        // Validasi format timestamp ISO 8601
+        if (!preg_match('/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d{3})?Z?$/', $xTimestamp)) {
+            throw new HttpResponseException(
+                response()->json(
+                    ResponseCode::INVALID_FIELD->toResponse(
+                        ['errors' => ['X-Timestamp' => 'Format timestamp tidak valid. Gunakan format ISO 8601 (YYYY-MM-DDTHH:MM:SS.sssZ)']],
+                        'Validasi gagal'
+                    ),
+                    ResponseCode::INVALID_FIELD->getHttpStatus()
+                )
+            );
+        }
+
+        // Validasi timestamp tidak lebih dari 5 menit dari waktu sekarang
+        try {
+            $timestamp = new \DateTime($xTimestamp);
+            $now = new \DateTime();
+            $diff = $now->getTimestamp() - $timestamp->getTimestamp();
+
+            if (abs($diff) > 300) { // 5 menit = 300 detik
+                throw new HttpResponseException(
+                    response()->json(
+                        ResponseCode::INVALID_FIELD->toResponse(
+                            ['errors' => ['X-Timestamp' => 'Timestamp expired. Maksimal selisih 5 menit dari waktu sekarang']],
+                            'Validasi gagal'
+                        ),
+                        ResponseCode::INVALID_FIELD->getHttpStatus()
+                    )
+                );
+            }
+        } catch (\Exception $e) {
+            throw new HttpResponseException(
+                response()->json(
+                    ResponseCode::INVALID_FIELD->toResponse(
+                        ['errors' => ['X-Timestamp' => 'Timestamp tidak dapat diproses']],
+                        'Validasi gagal'
+                    ),
+                    ResponseCode::INVALID_FIELD->getHttpStatus()
+                )
+            );
+        }
+
         // Cek apakah ini karena invalid API key
         if ($xApiKey !== $expectedApiKey) {
             throw new HttpResponseException(
@@ -215,19 +313,5 @@ class BalanceSummaryRequest extends FormRequest
             'ip'         => $this->ip(),
             'user_agent' => $this->userAgent()
         ]);
-
-        $acount = AccountBalance::where('account_number', $this->account_number)->first();
-
-        if (!$acount) {
-            throw new HttpResponseException(
-                response()->json(
-                    ResponseCode::ACCOUNT_NOT_FOUND->toResponse(
-                        null,
-                        'Nomor rekening tidak ditemukan'
-                    ),
-                    ResponseCode::ACCOUNT_NOT_FOUND->getHttpStatus()
-                )
-            );
-        }
     }
 }
diff --git a/config/config.php b/config/config.php
index 40f5a20..d99ae5e 100644
--- a/config/config.php
+++ b/config/config.php
@@ -5,4 +5,17 @@ return [
 
     // ZIP file password configuration
     'zip_password' => env('WEBSTATEMENT_ZIP_PASSWORD', 'statement123'),
+    /*
+    |--------------------------------------------------------------------------
+    | API Configuration
+    |--------------------------------------------------------------------------
+    |
+    | These configuration values are used for API authentication using HMAC
+    | signature validation. These keys are used to validate incoming API
+    | requests and ensure secure communication.
+    |
+    */
+
+    'api_key' => env('API_KEY'),
+    'secret_key' => env('SECRET_KEY'),
 ];