python encode()

问题:

Has hex codec been excluded from python 3.3? When I write the code

>>> s="Hallo"
>>> s.encode('hex')
Traceback (most recent call last):
  File "<pyshell#24>", line 1, in <module>
    s.encode('hex')
LookupError: unknown encoding: hex

What does that mean? I know about binascii.hexlify() but still .encode() method is nice! Any suggestion?

回答1:

No, using encode() to hexlify isn't nice.

The way you use the hex codec worked in Python 2 because you can call encode() on 8-bit strings in Python 2, ie you can encode something that is already encoded. That doesn't make sense. encode() is for encoding Unicode strings into 8-bit strings, not for encoding 8-bit strings as 8-bit strings.

In Python 3 you can't call encode() on 8-bit strings anymore, so the hex codec became pointless and was removed.

Although you theoretically could have a hex codec and use it like this:

>>> import codecs
>>> hexlify = codecs.getencoder('hex')
>>> hexlify(b'Blaah')[0]
b'426c616168'

Using binascii is easier and nicer:

>>> import binascii
>>> binascii.hexlify(b'Blaah')
b'426c616168'

回答2:

this is the same answer for the above but i modified it so it works with python 3.

import binascii
from Crypto.Cipher import AES
from Crypto import Random

def encrypt(passwrd, message):
    msglist = []
    key = bytes(passwrd, "utf-8")
    iv = Random.new().read(AES.block_size)
    cipher = AES.new(key, AES.MODE_CFB, iv)
    msg = iv + cipher.encrypt(bytes(message, "utf-8"))
    msg = binascii.hexlify(msg)
    for letter in str(msg):
        msglist.append(letter)
    msglist.remove("b")
    msglist.remove("'")
    msglist.remove("'")
    for letter in msglist:
        print(letter, end="")
    print("")

def decrypt(passwrd, message):
    msglist = []
    key = bytes(passwrd, "utf-8")
    iv = Random.new().read(AES.block_size)
    cipher = AES.new(key, AES.MODE_CFB, iv)
    msg = cipher.decrypt(binascii.unhexlify(bytes(message, "utf-8")))[len(iv):]
    for letter in str(msg):
        msglist.append(letter)
    msglist.remove("b")
    msglist.remove("'")
    msglist.remove("'")
    for letter in msglist:
        print(letter, end="")
    print("")