在安装laravel执行Auth 系统时，网站报错。

FatalThrowableError in Encrypter.php line 66:
Fatal error: Call to undefined function Illuminate\Encryption\openssl_encrypt()
in Encrypter.php line 66
at Encrypter->encrypt('xadrTxfVrZ7knoSYQDC2RREWMV1NxjMeq8HOuF18') in EncryptCookies.php line 131
at EncryptCookies->encrypt(object(Response)) in EncryptCookies.php line 59
at EncryptCookies->handle(object(Request), object(Closure))
at call_user_func_array(array(object(EncryptCookies), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 32
at Pipeline->Illuminate\Routing{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 102
at Pipeline->then(object(Closure)) in Router.php line 726
at Router->runRouteWithinStack(object(Route), object(Request)) in Router.php line 699
at Router->dispatchToRoute(object(Request)) in Router.php line 675
at Router->dispatch(object(Request)) in Kernel.php line 246
at Kernel->Illuminate\Foundation\Http{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 52
at Pipeline->Illuminate\Routing{closure}(object(Request)) in CheckForMaintenanceMode.php line 44
at CheckForMaintenanceMode->handle(object(Request), object(Closure))
at call_user_func_array(array(object(CheckForMaintenanceMode), 'handle'), array(object(Request), object(Closure))) in Pipeline.php line 124
at Pipeline->Illuminate\Pipeline{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 32
at Pipeline->Illuminate\Routing{closure}(object(Request))
at call_user_func(object(Closure), object(Request)) in Pipeline.php line 102
at Pipeline->then(object(Closure)) in Kernel.php line 132
at Kernel->sendRequestThroughRouter(object(Request)) in Kernel.php line 99
at Kernel->handle(object(Request)) in index.php line 53
at require_once('D:\laravel-v5.2.15\public\index.php') in server.php line 2