Implementing-cryptography-using-python

Chapter 2 ■ Cryptographic Protocols and Perfect Secrecy 55
Armed with this information, you can now encrypt plaintext to an encrypted
value and retrieve it only with a secret password, as shown here:
import binascii
def xorKey(secret):
secret = secret.encode()
hexstr = binascii.hexlify(secret)
key = int(hexstr, 16)
print ("key: ", key)
return key
def xorEnc(msg, key):
msg = msg.encode()
hexstr = binascii.hexlify(msg)
print ("hexstr: ", hexstr)
ciphertext = int(hexstr, 16) ^ key
print ("ciphertext: ", ciphertext)
return ciphertext
def xorDec(msg, key):
xorMsgKey = msg ^ key
back2hex = format(xorMsgKey, 'x')
print ("back2hex: ", back2hex)
evenpad = ('0' * (len(back2hex) % 2)) + back2hex
plaintext = binascii.unhexlify(evenpad)
print ("plaintext: ", plaintext)
return plaintext
key = xorKey("mysecret")
key2 = xorKey("wrongpass")
cipher = xorEnc('Hello world',key)
plain = xorDec(cipher,key)
wrongplain = xorDec(cipher, key2)
As you can see, only using the right key will result in the correct message.
The preceding should return the following:
key: 7888463101613466996
key: 2203408475604721431411
hexstr: 48656c6c6f20776f726c64
ciphertext: 87521610353724475878410512
back2hex: 48656c6c6f20776f726c64
plaintext: Hello world
back2hex: 48651b73793d757c617a63
plaintext: Hey=u|azc