cryptimer.py

from Crypto.Cipher import AES
import random

MIN_CIPHER = 1000000000000000
MAX_CIPHER = 1000000000010000
PLAIN_TEXT = 'test some plain text here'.rjust(32)


### encrypt ###
def generate_ciphers(ciphers_len):
    return [str(random.randint(MIN_CIPHER, MAX_CIPHER)) for i in range(ciphers_len)]

def encrypt(ciphers_len=100,plain_text=PLAIN_TEXT):
    ciphers = generate_ciphers(ciphers_len)
    hashes = []
    msg = plain_text
    hashes.append(hash(msg))
    for i in ciphers:
        cipher = AES.new(i,AES.MODE_ECB)
        msg = cipher.encrypt(msg) # encrypt the msg
        hashes.append(hash(msg)) # save the hash of the msg
    return msg, hashes # TODO: write to file for backup

def get_bruteforce_rate():
    '''
    return decryptions per second on average, for tuning encryption's parameters
    '''
    pass

### decrypt ###
def decrypt(encrypted_msg,hashes):
    msg = encrypted_msg
    for i in hashes[::-1]: # iterates over hashes, reversed since the last hash should be decrypted first
        j=MIN_CIPHER
        while j<MAX_CIPHER:
            cipher = AES.new(str(j),AES.MODE_ECB)
            candidate_msg = cipher.decrypt(msg) # try to decrypt
            if hash(candidate_msg) == i: # if we found the right hash we can continue to the next hash
                msg = candidate_msg
#                print "hash found!"
                break
            j+=1
    return msg 

### main ###
encrypted_msg,hashes = encrypt()
print decrypt(encrypted_msg,hashes)