Eloquent Encryption/Decryption for Laravel 5

Automatically encrypt and decrypt Laravel 5 Eloquent values.

READ THIS FIRST

Encrypted values are usually longer than plain text values. Sometimes much longer. You may find that the column widths in your database tables need to be extended to store the encrypted values.

If you are encrypting long strings such as JSON blobs then the encrypted values may be longer than a VARCHAR field can support, and you may need to extend your column types to TEXT or LONGTEXT.

What Does This Do?

This encrypts and decrypts columns stored in database tables in Laravel applications transparently, by encrypting data as it is stored in the model attributes and decrypting data as it is recalled from the model attributes.

All data that is encrypted is prefixed with a tag (default __ELOCRYPT__:) so that encrypted data can be easily identified.

This supports columns that store either encrypted or non-encrypted data to make migration easier. Data can be read from columns correctly regardless of whether it is encrypted or not but will be automatically encrypted when it is saved back into those columns.

Requirements and Recommendations

• Laravel 5.1 LTS (untested on 5.2 and later versions)
• PHP > 5.6.0 (need the hash_equals() function which was added in PHP 5.6)
• PHP openssl extension.
• A working OpenSSL implementation on your OS. OpenSSL comes pre-built with most Linux distributions and other forms of Unix such as *BSD. There may or may not be a working OpenSSL implementation on a Windows system depending on how your LA?P stack was built. I cannot offer support for installing or using ElocryptFive on systems that do not have an OpenSSL library.

Contributors

This is Darren Taylor's Laravel 4 "elocrypt" package, ported to Laravel 5. I have made the following additions/changes:

• Do the encryption in separate functions (encryptedAttribute and decryptedAttribute rather than inside __set and __get, and call those from setAttribute and getAttribute as that's more appropriate for Laravel 5 with the new casts features. So, for example, you can add a field to $casts and also to $encrypts so that an array can be cast to a JSON string first, and then encrypted. It should also work for Lumen.

• Prefix all encrypted values with a tag string (default __ELOCRYPT__: ) so that plain text data can be detected and handled correctly. The task of writing a script to traverse your existing database and update all plain text data to encrypted data is left to the reader.

The original Laravel 4 package is here: https://github.com/dtisgodsson/elocrypt

Thanks to Brandon Surowiec for some extensive refactoring of the internal methods.

Installation

This package can be installed via Composer by adding the following to your composer.json file:

    "require": {
        "delatbabel/elocryptfive": "~1.0"
    }

You must then run the following command:

    composer update

Once composer update has finished, then add the service provider to the providers array in your application's config/app.php file:

    'providers' => [
        ...
        Delatbabel\Elocrypt\ElocryptServiceProvider::class,
    ],

Configuration

Publish the config file with:

    php artisan vendor:publish --provider='Delatbabel\Elocrypt\ElocryptServiceProvider'

You may then change the default prefix tag string in your .env config file:

    ELOCRYPT_PREFIX=__This_is_encrypted_data__

or alternatively you can change the default right in the config/elocrypt.php file:

    return [
        'prefix' => env('ELOCRYPT_PREFIX', '__This_is_encrypted_data__')
    ]

Usage

Simply reference the Elocrypt trait in any Eloquent Model you wish to apply encryption to and define an $encrypts array containing a list of the attributes to encrypt.

For example:

    use Delatbabel\Elocrypt\Elocrypt;

    class User extends Eloquent {

        use Elocrypt;
       
        /**
         * The attributes that should be encrypted on save.
         *
         * @var array
         */
        protected $encrypts = [
            'address_line_1', 'first_name', 'last_name', 'postcode'
        ];
    }

You can combine $casts and $encrypts to store encrypted arrays. An array will first be converted to JSON and then encrypted.

For example:

    use Delatbabel\Elocrypt\Elocrypt;

    class User extends Eloquent {

        use Elocrypt;

        protected $casts = ['extended_data' => 'array'];

        protected $encrypts = ['extended_data'];
    }

How it Works?

By including the Elocrypt trait, the setAttribute() and getAttributeFromArray() methods provided by Eloquent are overridden to include an additional step. This additional step simply checks whether the attribute being set or get is included in the $encrypts array on the model, and either encrypts/decrypts it accordingly.

Summary of Methods in Illuminate\Database\Eloquent\Model

This surveys the major methods in the Laravel Model class as of Laravel v 5.1.12 and checks to see how those models set attributes and hence how they are affected by this trait.

• constructor -- calls fill()
• fill() -- calls setAttribute() which has been extended to encrypt the data.
• hydrate() -- TBD
• create() -- calls constructor and hence fill()
• firstOrCreate -- calls constructor
• firstOrNew -- calls constructor
• updateOrCreate -- calls fill()
• update() -- calls fill()
• toArray() -- calls attributesToArray()
• jsonSerialize() -- calls toArray()
• toJson() -- calls toArray()
• attributesToArray() -- calls getArrayableAttributes().
• getAttribute -- calls getAttributeValue()
• getAttributeValue -- calls getAttributeFromArray()
• getAttributeFromArray -- calls getArrayableAttributes()
• getArrayableAttributes -- has been extended here to decrypt the data.
• setAttribute -- has been extended here to encrypt the data.
• getAttributes -- has been extended here to decrypt the data.

Keys and IVs

The key and encryption algorithm used are as per the Laravel Encrypter service, and defined in config/app.php as follows:

    'key' => env('APP_KEY', 'SomeRandomString'),

    'cipher' => 'AES-256-CBC',

I recommend generating a random 32 character string for the encryption key, and using AES-256-CBC as the cipher for encrypting data. If you are encrypting long data strings then AES-256-CBC-HMAC-SHA1 will be better.

The IV for encryption is randomly generated.

FAQ

Manually Encrypting Data

You can manually encrypt or decrypt data using the encryptedAttribute() and decryptedAttribute() functions. An example is as follows:

    $user = new User();
    $encryptedEmail = $user->encryptedAttribute(Input::get("email"));

Encryption and Searching

You will not be able to search on encrypted data, because it is encrypted. Comparing encrypted values would require a fixed IV which introduces security issues.

If you need to search on data then either:

• Leave it unencrypted, or
• Hash the data and search on the hash instead of the encrypted value. Use a well known hash algorithm such as SHA256.

You could store both a hashed and an encrypted value, use the hashed value for searching and retrieve the encrypted value for other uses.

Encryption and Authentication

The same problem with searching applies for authentication because authentication requires a user search.

If you have an authentication table where you encrypt the user data including the login data (for example the email), this will prevent Auth::attempt from working. For example this code will not work:

    $auth = Auth::attempt(array(
                "email"     =>  Input::get("email"),
                "password"  =>  Input::get("password"),
    ), $remember);

As for searching, comparing the encrypted email will not work, because it would require a fixed IV which introduces security issues.

What you will need to do instead is to hash the email address using a well known hash function (e.g. SHA256 or RIPE-MD160) rather than encrypt it, and then in the Auth::attempt function you can compare the hashes.

If you need access to the email address then you could store both a hashed and an encrypted email address, use the hashed value for authentication and retrieve the encrypted value for other uses (e.g. sending emails).