CS challenge 2 - Submarine

aes_cbc_cipher.py

import base64
from Crypto.Cipher import AES

class AES_CBC_Cipher:
    def __init__( self, key ):
        self.key = key

    def pad(self, s):
        return s + (AES.block_size - len(s) % AES.block_size) * chr(AES.block_size - len(s) % AES.block_size)
    def unpad(self, s):
        return s[:-ord(s[len(s)-1:])]

    def encrypt( self, iv, raw ):
        raw = self.pad(raw)

        cipher = AES.new( self.key, AES.MODE_CBC, iv )
        return base64.b64encode( iv + cipher.encrypt( raw ) ) 

    def decrypt( self, enc ):
        enc = base64.b64decode(enc)
        iv = enc[:16]
        cipher = AES.new(self.key, AES.MODE_CBC, iv )
        return self.unpad(cipher.decrypt( enc[16:] ))

submarine.py

from aes_cbc_cipher import AES_CBC_Cipher
from Crypto import Random

secret_key = "abcdefghijklmnop" # not the real one =)

def validate_credentials(user, password):
    if user == "qwerty" and password == "asdf":
        return True
    else:
        return False

def login(user, password):

    if not validate_credentials(user, password):
        return False

    cipher = AES_CBC_Cipher(secret_key)
    
    IV = Random.new().read(16)
    return cipher.encrypt(IV, user)

def main():

    token = raw_input("Do you have a token? (y/n)\n")

    if token == "y":
        ciphertext = raw_input("token?\n")

        cipher = AES_CBC_Cipher(secret_key)
        user = cipher.decrypt(ciphertext)

        print "You are logged in as", user
    else:    
        user = raw_input("user?\n")
        password = raw_input("password?\n")

        token = login(user, password)

        if not token:
            print "Wrong credentials\n"
        else:
            print "Success. here's your token:"
            print token

if __name__ == "__main__":
    main()

Any hint?. Is it along the lines of padding oracle attack?

@shaduk without an oracle huh? lol