diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/CHANGELOG.md b/plugins/_bundled/sirsoft-pay_nhnkcp/CHANGELOG.md
index cce347b9..794174ce 100644
--- a/plugins/_bundled/sirsoft-pay_nhnkcp/CHANGELOG.md
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/CHANGELOG.md
@@ -4,6 +4,12 @@
 형식은 [Keep a Changelog](https://keepachangelog.com/ko/1.1.0/)를 따르며,
 [Semantic Versioning](https://semver.org/lang/ko/)을 준수합니다.
 
+## [Unreleased]
+
+### Fixed
+
+- 비회원 NHN KCP 주문완료/주문상세에서 매출전표 조회가 인증 사용자 전용 라우트에 막히지 않도록 게스트 주문 토큰과 결제 성공 후 임시 영수증 쿠키 접근을 지원했습니다.
+
 ## [1.0.0-beta.5] - 2026-06-23
 
 ### Fixed
diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/src/Concerns/IssuesReceiptCookie.php b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Concerns/IssuesReceiptCookie.php
new file mode 100644
index 00000000..84666529
--- /dev/null
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Concerns/IssuesReceiptCookie.php
@@ -0,0 +1,69 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Plugins\Sirsoft\PayNhnkcp\Concerns;
+
+use Illuminate\Cookie\CookieJar;
+use Symfony\Component\HttpFoundation\Cookie;
+
+trait IssuesReceiptCookie
+{
+    public const RECEIPT_COOKIE_NAME = 'nhnkcp_receipt_token';
+    private const RECEIPT_COOKIE_TTL_MINUTES = 5;
+
+    protected function queueReceiptCookie(string $orderNumber): void
+    {
+        $expiresTs = time() + (self::RECEIPT_COOKIE_TTL_MINUTES * 60);
+        $signature = $this->signReceiptToken($orderNumber, $expiresTs);
+        $tokenValue = $orderNumber.'|'.$expiresTs.'|'.$signature;
+
+        /** @var CookieJar $jar */
+        $jar = app(CookieJar::class);
+
+        $jar->queue(new Cookie(
+            name: self::RECEIPT_COOKIE_NAME,
+            value: $tokenValue,
+            expire: $expiresTs,
+            path: '/',
+            domain: null,
+            secure: request()->isSecure(),
+            httpOnly: true,
+            raw: false,
+            sameSite: Cookie::SAMESITE_LAX,
+        ));
+    }
+
+    protected function verifyReceiptCookie(?string $cookieValue, string $expectedOrderNumber): bool
+    {
+        if (! is_string($cookieValue) || $cookieValue === '') {
+            return false;
+        }
+
+        $parts = explode('|', $cookieValue);
+        if (count($parts) !== 3) {
+            return false;
+        }
+
+        [$orderNumber, $expiresTs, $signature] = $parts;
+
+        if ($orderNumber !== $expectedOrderNumber) {
+            return false;
+        }
+
+        if (! ctype_digit($expiresTs) || (int) $expiresTs < time()) {
+            return false;
+        }
+
+        if (! ctype_xdigit($signature) || strlen($signature) !== 64) {
+            return false;
+        }
+
+        return hash_equals($this->signReceiptToken($orderNumber, (int) $expiresTs), $signature);
+    }
+
+    private function signReceiptToken(string $orderNumber, int $expiresTs): string
+    {
+        return hash_hmac('sha256', $orderNumber.'|'.$expiresTs, (string) config('app.key', ''));
+    }
+}
diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/PaymentCallbackController.php b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/PaymentCallbackController.php
index 94e5f13f..4156ebb5 100644
--- a/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/PaymentCallbackController.php
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/PaymentCallbackController.php
@@ -18,6 +18,7 @@ use Modules\Sirsoft\Ecommerce\Helpers\DeviceDetector;
 use Modules\Sirsoft\Ecommerce\Models\Order;
 use Modules\Sirsoft\Ecommerce\Services\OrderProcessingService;
 use Plugins\Sirsoft\PayNhnkcp\Concerns\PreventsReplayCallback;
+use Plugins\Sirsoft\PayNhnkcp\Concerns\IssuesReceiptCookie;
 use Plugins\Sirsoft\PayNhnkcp\Concerns\RecordsPaymentWindowClosure;
 use Plugins\Sirsoft\PayNhnkcp\Concerns\ResolvesEasyPayDisplay;
 use Plugins\Sirsoft\PayNhnkcp\Concerns\SanitizesPgResponse;
@@ -37,6 +38,7 @@ use Plugins\Sirsoft\PayNhnkcp\Services\NhnKcpApiService;
 class PaymentCallbackController
 {
     use PreventsReplayCallback;
+    use IssuesReceiptCookie;
     use RecordsPaymentWindowClosure;
     use ResolvesEasyPayDisplay;
     use SanitizesPgResponse;
@@ -217,6 +219,8 @@ class PaymentCallbackController
                     'transaction_id' => $order->payment?->transaction_id,
                 ]);
 
+                $this->queueReceiptCookie($ordrIdxx);
+
                 return redirect($this->resolveSuccessUrl($ordrIdxx));
             }
 
@@ -302,6 +306,7 @@ class PaymentCallbackController
             // Replay 가드: 동일 tno 가 이미 paid 상태면 중복 처리하지 않고 성공 페이지로 복귀
             if ($this->wasAlreadyPaid($tno)) {
                 $this->logReplayDetected($tno, $ordrIdxx, 'authCallback (card)');
+                $this->queueReceiptCookie($ordrIdxx);
 
                 return redirect($this->resolveSuccessUrl($ordrIdxx));
             }
@@ -359,6 +364,8 @@ class PaymentCallbackController
             // (기본 PG가 타 PG일 때 주문이 해당 PG provider로 생성되는 경우 대비)
             $order->payment()->update(['pg_provider' => 'nhnkcp']);
 
+            $this->queueReceiptCookie($ordrIdxx);
+
             return redirect($this->resolveSuccessUrl($ordrIdxx));
 
         } catch (LockTimeoutException $e) {
@@ -369,6 +376,8 @@ class PaymentCallbackController
             $latestOrder = $this->orderService->findByOrderNumber($ordrIdxx);
             if (($latestOrder?->payment?->isPaid() ?? false)
                 || $latestOrder?->order_status === OrderStatusEnum::PAYMENT_COMPLETE) {
+                $this->queueReceiptCookie($ordrIdxx);
+
                 return redirect($this->resolveSuccessUrl($ordrIdxx));
             }
 
@@ -740,6 +749,8 @@ class PaymentCallbackController
             ]));
         }
 
+        $this->queueReceiptCookie($ordrIdxx);
+
         return redirect($this->resolveSuccessUrl($ordrIdxx));
     }
 
diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/UserReceiptController.php b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/UserReceiptController.php
index ce69d344..723e5336 100644
--- a/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/UserReceiptController.php
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Controllers/UserReceiptController.php
@@ -8,11 +8,14 @@ use App\Services\PluginSettingsService;
 use Illuminate\Http\JsonResponse;
 use Illuminate\Http\Request;
 use Illuminate\Support\Facades\DB;
+use Modules\Sirsoft\Ecommerce\Services\GuestOrderAuthService;
+use Plugins\Sirsoft\PayNhnkcp\Concerns\IssuesReceiptCookie;
 use Plugins\Sirsoft\PayNhnkcp\Concerns\ResolvesEasyPayDisplay;
 use Plugins\Sirsoft\PayNhnkcp\Services\NhnKcpApiService;
 
 class UserReceiptController
 {
+    use IssuesReceiptCookie;
     use ResolvesEasyPayDisplay;
 
     private const PLUGIN_IDENTIFIER = 'sirsoft-pay_nhnkcp';
@@ -30,6 +33,7 @@ class UserReceiptController
     public function __construct(
         private readonly PluginSettingsService $pluginSettingsService,
         private readonly NhnKcpApiService $apiService,
+        private readonly GuestOrderAuthService $guestOrderAuthService,
     ) {}
 
     /**
@@ -41,20 +45,37 @@ class UserReceiptController
      * 결제 영수증 URL(신용카드)과 현금영수증 URL(현금/계좌이체)을 반환한다.
      * receipt_url 이 비어있으면 transaction_id (tno) 로 KCP 영수증 URL 을 동적 생성.
      *
-     * @param  Request  $request  인증된 사용자 요청
+     * @param  Request  $request  회원 또는 비회원 영수증 요청
      * @param  string  $orderNumber  주문번호
      * @return JsonResponse receipt_url / cash_receipt_url 또는 404
      */
     public function show(Request $request, string $orderNumber): JsonResponse
     {
         $user = $request->user();
-
-        $payment = DB::table('ecommerce_order_payments as p')
+        $query = DB::table('ecommerce_order_payments as p')
             ->join('ecommerce_orders as o', 'o.id', '=', 'p.order_id')
             ->where('o.order_number', $orderNumber)
-            ->where('o.user_id', $user->id)
             ->where('p.pg_provider', 'nhnkcp')
-            ->whereNotNull('p.transaction_id')
+            ->whereNotNull('p.transaction_id');
+
+        if ($user) {
+            $query->where('o.user_id', $user->id);
+        } else {
+            $order = $this->guestOrderAuthService->verifyToken($request->header('X-Guest-Order-Token'), $orderNumber);
+
+            if ($order) {
+                $query->whereNull('o.user_id')->where('o.id', $order->id);
+            } elseif ($this->verifyReceiptCookie($request->cookie(self::RECEIPT_COOKIE_NAME), $orderNumber)) {
+                $query->whereNull('o.user_id')
+                    ->where('o.id', function ($sub) use ($orderNumber) {
+                        $sub->select('id')->from('ecommerce_orders')->where('order_number', $orderNumber);
+                    });
+            } else {
+                return response()->json(['error' => 'Not found'], 404);
+            }
+        }
+
+        $payment = $query
             ->select([
                 'p.transaction_id',
                 'p.payment_meta',
diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/src/Providers/PayNhnkcpServiceProvider.php b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Providers/PayNhnkcpServiceProvider.php
new file mode 100644
index 00000000..d3729e65
--- /dev/null
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/src/Providers/PayNhnkcpServiceProvider.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Plugins\Sirsoft\PayNhnkcp\Providers;
+
+use App\Extension\BasePluginServiceProvider;
+use Illuminate\Cookie\Middleware\EncryptCookies;
+
+class PayNhnkcpServiceProvider extends BasePluginServiceProvider
+{
+    protected string $pluginIdentifier = 'sirsoft-pay_nhnkcp';
+
+    public function boot(): void
+    {
+        parent::boot();
+
+        // PG callback 이 발급하는 영수증 쿠키는 HMAC 으로 자체 무결성 보장하므로
+        // EncryptCookies 대상에서 제외한다. 암호화 대상이면 callback 응답에서
+        // 직접 발급한 평문 쿠키가 다음 API 요청에서 복호화 실패로 폐기될 수 있다.
+        // 값 동기화: IssuesReceiptCookie::RECEIPT_COOKIE_NAME 과 동일해야 함.
+        EncryptCookies::except(['nhnkcp_receipt_token']);
+    }
+}
diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/src/routes/api.php b/plugins/_bundled/sirsoft-pay_nhnkcp/src/routes/api.php
index 2f32d9b8..64b6128c 100644
--- a/plugins/_bundled/sirsoft-pay_nhnkcp/src/routes/api.php
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/src/routes/api.php
@@ -29,10 +29,11 @@ Route::post('/payment/close-report', [PaymentCloseReportController::class, 'stor
 Route::post('/payment/retry', [PaymentRetryController::class, 'store'])
     ->name('payment.retry');
 
-Route::middleware(['auth:sanctum'])->group(function () {
-    Route::get('/user/orders/{orderNumber}/receipt', [UserReceiptController::class, 'show'])
-        ->name('user.orders.receipt');
+Route::get('/user/orders/{orderNumber}/receipt', [UserReceiptController::class, 'show'])
+    ->middleware('optional.sanctum')
+    ->name('user.orders.receipt');
 
+Route::middleware(['auth:sanctum'])->group(function () {
     // 테스트 모드 가상계좌 모의입금 정보 (입금대기 상태일 때만 데이터 반환)
     Route::get('/user/orders/{orderNumber}/vbank-mock-deposit-info', [UserVbankMockDepositController::class, 'show'])
         ->name('user.orders.vbank-mock-deposit-info');
diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/tests/Feature/Controllers/UserReceiptControllerTest.php b/plugins/_bundled/sirsoft-pay_nhnkcp/tests/Feature/Controllers/UserReceiptControllerTest.php
index e8f07439..b31af577 100644
--- a/plugins/_bundled/sirsoft-pay_nhnkcp/tests/Feature/Controllers/UserReceiptControllerTest.php
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/tests/Feature/Controllers/UserReceiptControllerTest.php
@@ -5,15 +5,26 @@ declare(strict_types=1);
 namespace Plugins\Sirsoft\PayNhnkcp\Tests\Feature\Controllers;
 
 use App\Models\User;
+use Illuminate\Cookie\Middleware\EncryptCookies;
+use Illuminate\Support\Facades\Hash;
 use Modules\Sirsoft\Ecommerce\Database\Factories\OrderFactory;
 use Modules\Sirsoft\Ecommerce\Database\Factories\OrderPaymentFactory;
 use Modules\Sirsoft\Ecommerce\Enums\OrderStatusEnum;
 use Modules\Sirsoft\Ecommerce\Enums\PaymentMethodEnum;
 use Modules\Sirsoft\Ecommerce\Enums\PaymentStatusEnum;
+use Modules\Sirsoft\Ecommerce\Services\GuestOrderAuthService;
 use Plugins\Sirsoft\PayNhnkcp\Tests\PluginTestCase;
 
 class UserReceiptControllerTest extends PluginTestCase
 {
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        // 운영에서는 PayNhnkcpServiceProvider::boot 가 동일하게 등록한다.
+        EncryptCookies::except(['nhnkcp_receipt_token']);
+    }
+
     public function test_receipt_response_includes_easy_pay_display_label(): void
     {
         app()->setLocale('ko');
@@ -62,4 +73,121 @@ class UserReceiptControllerTest extends PluginTestCase
             $data['payment_method_display_label'] ?? null,
         );
     }
+
+    public function test_guest_receipt_requires_valid_token(): void
+    {
+        $order = $this->createGuestOrder();
+        $this->createKcpPayment($order, 'KCP_TNO_GUEST_001');
+
+        $this->getJson("/api/plugins/sirsoft-pay_nhnkcp/user/orders/{$order->order_number}/receipt")
+            ->assertNotFound();
+
+        $this->withHeader('X-Guest-Order-Token', (time() + 1800).'|'.str_repeat('0', 64))
+            ->getJson("/api/plugins/sirsoft-pay_nhnkcp/user/orders/{$order->order_number}/receipt")
+            ->assertNotFound();
+    }
+
+    public function test_guest_receipt_returns_receipt_url_with_valid_header_token(): void
+    {
+        app()->setLocale('ko');
+
+        $order = $this->createGuestOrder();
+        $this->createKcpPayment($order, 'KCP_TNO_GUEST_002');
+
+        $response = $this->withHeader('X-Guest-Order-Token', $this->issueGuestToken($order))
+            ->getJson("/api/plugins/sirsoft-pay_nhnkcp/user/orders/{$order->order_number}/receipt")
+            ->assertOk()
+            ->assertJsonPath('receipt_url', 'https://testadmin8.kcp.co.kr/assist/bill.BillActionNew.do?cmd=card_bill&tno=KCP_TNO_GUEST_002&order_no='.$order->order_number.'&trade_mony=1000');
+
+        $this->assertContains($response->json('payment_method_label'), ['신용카드', 'Credit Card']);
+    }
+
+    public function test_guest_receipt_returns_receipt_url_with_valid_cookie(): void
+    {
+        $order = $this->createGuestOrder();
+        $this->createKcpPayment($order, 'KCP_TNO_GUEST_003');
+
+        $this->withUnencryptedCookie('nhnkcp_receipt_token', $this->issueReceiptCookie($order->order_number))
+            ->withCredentials()
+            ->getJson("/api/plugins/sirsoft-pay_nhnkcp/user/orders/{$order->order_number}/receipt")
+            ->assertOk()
+            ->assertJsonPath('receipt_url', 'https://testadmin8.kcp.co.kr/assist/bill.BillActionNew.do?cmd=card_bill&tno=KCP_TNO_GUEST_003&order_no='.$order->order_number.'&trade_mony=1000');
+    }
+
+    public function test_guest_token_for_other_order_cannot_access_receipt(): void
+    {
+        $order1 = $this->createGuestOrder();
+        $order2 = $this->createGuestOrder();
+        $this->createKcpPayment($order1, 'KCP_TNO_GUEST_004');
+        $this->createKcpPayment($order2, 'KCP_TNO_GUEST_005');
+
+        $this->withHeader('X-Guest-Order-Token', $this->issueGuestToken($order1))
+            ->getJson("/api/plugins/sirsoft-pay_nhnkcp/user/orders/{$order2->order_number}/receipt")
+            ->assertNotFound();
+    }
+
+    public function test_authenticated_user_cannot_access_guest_order_receipt_via_token(): void
+    {
+        $user = User::factory()->create();
+        $order = $this->createGuestOrder();
+        $this->createKcpPayment($order, 'KCP_TNO_GUEST_006');
+
+        $this->actingAs($user)
+            ->withHeader('X-Guest-Order-Token', $this->issueGuestToken($order))
+            ->getJson("/api/plugins/sirsoft-pay_nhnkcp/user/orders/{$order->order_number}/receipt")
+            ->assertNotFound();
+    }
+
+    private function createGuestOrder()
+    {
+        return OrderFactory::new()->create([
+            'user_id' => null,
+            'guest_lookup_password_hash' => Hash::make('test1234'),
+            'order_number' => 'ORD-KCP-GUEST-' . random_int(10000, 99999),
+            'order_status' => OrderStatusEnum::PAYMENT_COMPLETE,
+            'total_amount' => 1000,
+            'total_due_amount' => 0,
+            'total_paid_amount' => 1000,
+            'paid_at' => now(),
+        ]);
+    }
+
+    private function createKcpPayment($order, string $transactionId): void
+    {
+        OrderPaymentFactory::new()->create([
+            'order_id' => $order->id,
+            'payment_status' => PaymentStatusEnum::PAID,
+            'payment_method' => PaymentMethodEnum::CARD,
+            'pg_provider' => 'nhnkcp',
+            'transaction_id' => $transactionId,
+            'paid_amount_local' => 1000,
+            'paid_at' => now(),
+            'payment_meta' => [],
+        ]);
+    }
+
+    private function issueGuestToken($order): string
+    {
+        $svc = app(GuestOrderAuthService::class);
+        $rc = new \ReflectionClass($svc);
+        $signMethod = $rc->getMethod('sign');
+        $signMethod->setAccessible(true);
+        $suffixMethod = $rc->getMethod('passwordHashSuffix');
+        $suffixMethod->setAccessible(true);
+
+        $expiresTs = time() + 1800;
+        $suffix = $suffixMethod->invoke($svc, $order);
+        $sig = $signMethod->invoke($svc, $order->order_number, (int) $order->id, $expiresTs, $suffix);
+
+        return $expiresTs.'|'.$sig;
+    }
+
+    private function issueReceiptCookie(string $orderNumber): string
+    {
+        $expiresTs = time() + 300;
+        $payload = $orderNumber.'|'.$expiresTs;
+        $signature = hash_hmac('sha256', $payload, (string) config('app.key', ''));
+
+        return $payload.'|'.$signature;
+    }
 }
diff --git a/plugins/_bundled/sirsoft-pay_nhnkcp/tests/Unit/Concerns/IssuesReceiptCookieTest.php b/plugins/_bundled/sirsoft-pay_nhnkcp/tests/Unit/Concerns/IssuesReceiptCookieTest.php
new file mode 100644
index 00000000..e3f9f09f
--- /dev/null
+++ b/plugins/_bundled/sirsoft-pay_nhnkcp/tests/Unit/Concerns/IssuesReceiptCookieTest.php
@@ -0,0 +1,92 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Plugins\Sirsoft\PayNhnkcp\Tests\Unit\Concerns;
+
+use Plugins\Sirsoft\PayNhnkcp\Concerns\IssuesReceiptCookie;
+use Plugins\Sirsoft\PayNhnkcp\Tests\PluginTestCase;
+
+/**
+ * 영수증 cookie HMAC 검증 로직 단위 테스트.
+ *
+ * HTTP 통합(callback → Set-Cookie → 후속 호출에서 cookie 자동 첨부) 검증은
+ * Playwright 시나리오로 다룬다 — Laravel 의 EncryptCookies 미들웨어와 PHPUnit
+ * HTTP 테스트 환경의 cookie 처리 흐름이 production 과 일부 다르기 때문.
+ */
+class IssuesReceiptCookieTest extends PluginTestCase
+{
+    private object $subject;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        // IssuesReceiptCookie 는 trait — 익명 클래스로 인스턴스화
+        $this->subject = new class {
+            use IssuesReceiptCookie {
+                verifyReceiptCookie as public;
+            }
+        };
+    }
+
+    public function test_verify_succeeds_with_fresh_token_matching_order_number(): void
+    {
+        $orderNumber = 'ORD-RECEIPT-12345';
+        $cookieValue = $this->buildToken($orderNumber, time() + 300);
+
+        $this->assertTrue($this->subject->verifyReceiptCookie($cookieValue, $orderNumber));
+    }
+
+    public function test_verify_fails_when_cookie_missing(): void
+    {
+        $this->assertFalse($this->subject->verifyReceiptCookie(null, 'ORD-RECEIPT-99999'));
+        $this->assertFalse($this->subject->verifyReceiptCookie('', 'ORD-RECEIPT-99999'));
+    }
+
+    public function test_verify_fails_when_token_format_invalid(): void
+    {
+        // 3-파트 미충족
+        $this->assertFalse($this->subject->verifyReceiptCookie('ORD-X|123', 'ORD-X'));
+        // 만료시각이 숫자 아님
+        $this->assertFalse($this->subject->verifyReceiptCookie('ORD-X|abc|'.str_repeat('0', 64), 'ORD-X'));
+        // 서명이 hex 아님
+        $this->assertFalse($this->subject->verifyReceiptCookie('ORD-X|'.(time() + 300).'|invalid_sig', 'ORD-X'));
+    }
+
+    public function test_verify_fails_when_token_expired(): void
+    {
+        $orderNumber = 'ORD-RECEIPT-EXPIRED';
+        $expiredCookie = $this->buildToken($orderNumber, time() - 60);
+
+        $this->assertFalse($this->subject->verifyReceiptCookie($expiredCookie, $orderNumber));
+    }
+
+    public function test_verify_fails_when_order_number_mismatched(): void
+    {
+        $tokenFor = 'ORD-RECEIPT-AAA';
+        $accessing = 'ORD-RECEIPT-BBB';
+        $cookieValue = $this->buildToken($tokenFor, time() + 300);
+
+        // cookie 의 payload 가 다른 주문번호이므로 reject
+        $this->assertFalse($this->subject->verifyReceiptCookie($cookieValue, $accessing));
+    }
+
+    public function test_verify_fails_when_signature_tampered(): void
+    {
+        $orderNumber = 'ORD-RECEIPT-TAMPER';
+        $expiresTs = time() + 300;
+        // 정상 서명 대신 0으로 가득 찬 위조 서명
+        $tampered = $orderNumber.'|'.$expiresTs.'|'.str_repeat('0', 64);
+
+        $this->assertFalse($this->subject->verifyReceiptCookie($tampered, $orderNumber));
+    }
+
+    private function buildToken(string $orderNumber, int $expiresTs): string
+    {
+        $payload = $orderNumber.'|'.$expiresTs;
+        $signature = hash_hmac('sha256', $payload, (string) config('app.key', ''));
+
+        return $orderNumber.'|'.$expiresTs.'|'.$signature;
+    }
+}