Crypto Challenge! Encryption and Decryption with PBKDF2 and AES

I was challenged to make a functioning PHP program to encrypt text with a password, as part of my criptography study group.

Some may think dealing with cryptography is hard, but in reality, dealing with PHP is way harder.

How it works

Avoid spoilers by trying it out by yourself! Instructions are below.

The encrypt_thing.php script will prompt you for a secret you wish to save, e.g. your credit card details (they sure will be safe), and then it will prompt you for a password to store it. Finally, it will create a readable file called encrypted_secret.txt.

$ php encrypt_thing.php

Type a secret you wish to store. It will be encrypted and stored in a file.
> Hello, world!
Create a password to protect this file.
> 123456
Your secret has been encrypted and stored in the 'encrypted_secret.txt' file.

Now if we take a look at the encrypted_secret.txt file, it will contain some encrypted stuff.

$ cat encrypted_secret.txt

4fc435f68fd016b58cb514a1fb55190e54a21d35d449440fb0ba8dbf1e24772159642b3168655a44495a353541626870432f4f5542413d3d

The decrypt_thing.php will decrypt the encrypted_secret.txt. To do so, it will prompt you for your password and display the original secret to you.

$ php decrypt_thing.php

Type in the password you've used to encrypt the 'encrypted_secret.txt' file.
> 123456
Your original secret was:
Hello, world!

Usage

Running with docker - more portable and doesn't taint your machine with PHP

Run script with ./docker-run <script_name.php>, it will do everything automatically.

e.g. run the encryption script with ./docker-run encrypt_thing.php.

Running locally

If you're brave enough to have PHP installed locally, just run the desired script, e.g. php encrypt_thing.php.