Laravel 5：未定义的变量

When I am printing return value from controller in view page some error are showing. Please help me to solve this issue. I have added my code below

Error

Undefined variable: encrypt (View: C:\xampp\htdocs\ctesources\views\test\frontend.blade.php)

ProfileimageController.php

public function index($id)
    {
        $details             = User::select('id', 'created_at')->findOrFail($id);
        $encrypt             = md5($details->id.$details->created_at);
        return response($encrypt);
}

routes.php

Route::get('/', function () {
    return view('welcome');
});

Route::get('/dashboard', ['middleware' => 'auth', function () {
    return view('pages.dashboard');
}]);

// Test Env for frontend jquery
Route::get('ct', function() {
    return view('test.frontend');
});

// user input
Route::post('update/input', [
    'before'  => 'csrf',
    'as'      => 'userinput',
    'uses'    => 'InputController@update'
]);



/*
|--------------------------------------------------------------------------
| Authentication routes
|--------------------------------------------------------------------------
|
| All the functionality of auth
*/
// Authentication routes...
Route::get('auth/login', 'Auth\AuthController@getLogin');
Route::post('auth/login', 'Auth\AuthController@postLogin');
Route::get('auth/logout', 'Auth\AuthController@getLogout');

// Registration routes...
Route::get('auth/register', 'Auth\AuthController@getRegister');
Route::post('auth/register', 'Auth\AuthController@postRegister');

// Password reset link request routes...
Route::get('password/email', 'Auth\PasswordController@getEmail');
Route::post('password/email', 'Auth\PasswordController@postEmail');

// Password reset routes...
Route::get('password/reset/{token}', 'Auth\PasswordController@getReset');
Route::post('password/reset', 'Auth\PasswordController@postReset');

/*
|--------------------------------------------------------------------------
| Tag Interest
|--------------------------------------------------------------------------
|
| All the functionality of tag interest
*/
// Tag Interest Listout
Route::get('tag/interest', 'TagController@index');

// Tag Interest Insert
Route::post('/interest/update', [
    'before'  => 'csrf',
    'as'      => 'interestupdate',
    'uses'    => 'TagController@store'
]);

// Tag Interest Delete
Route::post('/interest/delete', [
    'before'  => 'csrf',
    'as'      => 'interestdelete',
    'uses'    => 'TagController@destroy'
]);


/*
|--------------------------------------------------------------------------
| Tag Language
|--------------------------------------------------------------------------
|
| All the functionality of tag language
*/
// Tag Languages Listout
Route::get('/tag/language', 'TaglanguageController@index');

// Tag Languages Insert
Route::post('/language/insert', [
    'before'  => 'csrf',
    'as'      => 'taglanguageinsert',
    'uses'    => 'TaglanguageController@store'
]);

// Tag Languages Update
Route::post('/language/update', [
    'before'  => 'csrf',
    'as'      => 'taglanguageupdate',
    'uses'    => 'TaglanguageController@update'
]);

// Tag Languages Delete
Route::post('/language/delete', [
    'before'  => 'csrf',
    'as'      => 'taglanguagedelete',
    'uses'    => 'TaglanguageController@destroy'
]);


/*
|--------------------------------------------------------------------------
| Profile Image
|--------------------------------------------------------------------------
|
| All the functionality of profile image
*/
// Upload profile image
Route::post('/uploadProfile/image/{id}',[
    'before'  => 'csrf',
    'as'      => 'uploadprofileimage',
    'uses'    => 'ProfileimageController@store']);

// View profile image
Route::get('/viewProfile/image/{id}', [
    'as' => 'viewprofileimage', 'uses' => 'ProfileimageController@index']);

// Delete profile image
Route::post('/deleteProfile/image',[
    'before'  => 'csrf',
    'as'      => 'deleteprofileimage',
    'uses'    => 'ProfileimageController@destroy']);




/*Route::any('/uploadProfile/image/{id}', function(){
    var_dump(Input::file('file'));
});*/




Route::post('update/privacy', function() {
    return var_dump($_POST);
});

frontend.blade.php

<?php
   echo $encrypt;
 ?>