Laravel Crypt::decrypt migration to ruby - php

Question

for a customer we are migrating a Laravel application to a Ruby application. We have some data stored in the database that we would like to decrypt in the ruby world.
This is the laravel part that was used to encrypt the data: https://laravel.com/docs/5.0/encryption
Now when importing the data to ruby we need a counter part that can decrypt the data.
In the laravel console I was able to decrypt the data like this:
>>> Crypt::decrypt('eyJpdiI6ImZyek9ZTjJNSW5ZYlhSa2ZYUldVbEE9PSIsInZhbHVlIjoia20zMTRLWEpCdXM2K05DZDBHSlE5SDlcL2pYVXk5aE5RWWR3dHFQT1dGQzA9IiwibWFjIjoiZWZlNGE3NTRhMDDlNzk2MjhlYjI1Mzc1NGNiYmRjNDMwZjM1NzdiMzkyZTU4ZjA4ZDNkMGE0YjUyOTBjMDAzOCJA')
=> "123123123123"
I am no laravel expert, but in the app.php file a secret key was set. So I need to be able to pass it somehow to the decrypt function.
The goal is to have a ruby function that takes the laravel password, encryption key and returns the decrypted value.
def decrypt_laravel_crypt(value, encryption_key)
end
Thanks for the help!

Answer 1

You can reverse engineer Laravel's Encrypter::decrypt method using mostly standard libs. Laravel will serialize data before encrypting it unless told explicitly not to. This means attempting to unserialize the decrypted string prior to using it.
require 'base64'
require 'openssl'
require 'json'
require 'php_serialize'
def lara_decrypt(encryptedString, appKey)
data = JSON.parse(Base64::decode64(encryptedString))
decipher = OpenSSL::Cipher.new('aes-256-cbc')
decipher.decrypt
decipher.key = Base64::decode64(appKey)
decipher.iv = Base64::decode64(data['iv'])
decrypted = decipher.update(Base64::decode64(data['value'])) + decipher.final
begin
PHP.unserialize(decrypted)
rescue
decrypted
end
end
Also when you set the app key be sure to drop base64: from the beginning of it (if it's there).