Python中的AES-128 CBC解密

Question

我正在尝试在python中实现此代码（我是python新手），它给我以下错误：

attribute error:“str”对象没有属性“decode”

如果我们删除 .decode（“十六进制”）只是为了避免这样的错误：

from itertools import product
from Crypto.Cipher import AES
import Crypto.Cipher.AES

key = ('2b7e151628aed2a6abf7158809cf4f3c').decode('hex')
IV = ('000102030405060708090a0b0c0d0e0f').decode('hex')
plaintext1 = ('6bc1bee22e409f96e93d7e117393172a').decode('hex')
plaintext2 = ('ae2d8a571e03ac9c9eb76fac45af8e51').decode('hex')
plaintext3 = ('30c81c46a35ce411e5fbc1191a0a52ef').decode('hex')
cipher = AES.new(key, AES.MODE_CBC, IV)
ciphertext = cipher.encrypt(plaintext1 + plaintext2 + plaintext3)
(ciphertext).encode('hex')
decipher = AES.new(key, AES.MODE_CBC, IV)
plaintext = decipher.decrypt(ciphertext)
(plaintext).encode('hex')

但它给我以下错误：

ValueError:IV必须为16字节长

因为算法需要. decode（'hex'），我必须删除

from itertools import product
from Crypto.Cipher import AES
import Crypto.Cipher.AES

key = ('2b7e151628aed2a6abf7158809cf4f3c')
IV = ('000102030405060708090a0b0c0d0e0f')
plaintext1 = ('6bc1bee22e409f96e93d7e117393172a')
plaintext2 = ('ae2d8a571e03ac9c9eb76fac45af8e51')
plaintext3 = ('30c81c46a35ce411e5fbc1191a0a52ef')
cipher = AES.new(key,AES.MODE_CBC,IV)
ciphertext = cipher.encrypt(plaintext1 + plaintext2 + plaintext3)
(ciphertext).encode('hex')
decipher = AES.new(key,AES.MODE_CBC,IV)
plaintext = decipher.decrypt(ciphertext)
(plaintext).encode('hex')

有没有人知道我该怎么做才能使这段代码工作？

Answer 1

您使用的是蟒蛇 3，而不是蟒蛇 2。你不能在Python 3中的字符串上使用decode（），它们已经是文本，所以字节到字节的编解码器（如“十六进制”）不能以这种方式应用。

改用binascii模块：

from binascii import hexlify, unhexlify

key = unhexlify('2b7e151628aed2a6abf7158809cf4f3c')
IV = unhexlify('000102030405060708090a0b0c0d0e0f')
plaintext1 = unhexlify('6bc1bee22e409f96e93d7e117393172a')
plaintext2 = unhexlify('ae2d8a571e03ac9c9eb76fac45af8e51')
plaintext3 = unhexlify('30c81c46a35ce411e5fbc1191a0a52ef')

和

ciphertext_hex = hexlify(ciphertext)
# ...
plaintext_hex = hexlify(plaintext)

因此，要将十六进制字符串解码为字节，请使用＜code＞binascii。unaxlify（），要将其编码回十六进制，请使用binascii.hexlify。请注意，您不能就地转换数据，您必须将结果存储回变量中（或打印出值等）。

演示：

>>> from Crypto.Cipher import AES
>>> import Crypto.Cipher.AES
>>> from binascii import hexlify, unhexlify
>>> key = unhexlify('2b7e151628aed2a6abf7158809cf4f3c')
>>> IV = unhexlify('000102030405060708090a0b0c0d0e0f')
>>> plaintext1 = unhexlify('6bc1bee22e409f96e93d7e117393172a')
>>> plaintext2 = unhexlify('ae2d8a571e03ac9c9eb76fac45af8e51')
>>> plaintext3 = unhexlify('30c81c46a35ce411e5fbc1191a0a52ef')
>>> cipher = AES.new(key,AES.MODE_CBC,IV)
>>> ciphertext = cipher.encrypt(plaintext1 + plaintext2 + plaintext3)
>>> hexlify(ciphertext)
b'7649abac8119b246cee98e9b12e9197d5086cb9b507219ee95db113a917678b273bed6b8e3c1743b7116e69e22229516'
>>> decipher = AES.new(key,AES.MODE_CBC,IV)
>>> plaintext = decipher.decrypt(ciphertext)
>>> plaintext == plaintext1 + plaintext2 + plaintext3  # test if decryption was successful
True
>>> hexlify(plaintext)
b'6bc1bee22e409f96e93d7e117393172aae2d8a571e03ac9c9eb76fac45af8e5130c81c46a35ce411e5fbc1191a0a52ef'