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"""Pure-Python AES implementation."""
from cryptomath import *
from AES import *
from rijndael import rijndael
def new(key, mode, IV):
return Python_AES(key, mode, IV)
class Python_AES(AES):
def __init__(self, key, mode, IV):
AES.__init__(self, key, mode, IV, "python")
self.rijndael = rijndael(key, 16)
self.IV = IV
def encrypt(self, plaintext):
AES.encrypt(self, plaintext)
plaintextBytes = stringToBytes(plaintext)
chainBytes = stringToBytes(self.IV)
#CBC Mode: For each block...
for x in range(len(plaintextBytes)/16):
#XOR with the chaining block
blockBytes = plaintextBytes[x*16 : (x*16)+16]
for y in range(16):
blockBytes[y] ^= chainBytes[y]
blockString = bytesToString(blockBytes)
#Encrypt it
encryptedBytes = stringToBytes(self.rijndael.encrypt(blockString))
#Overwrite the input with the output
for y in range(16):
plaintextBytes[(x*16)+y] = encryptedBytes[y]
#Set the next chaining block
chainBytes = encryptedBytes
self.IV = bytesToString(chainBytes)
return bytesToString(plaintextBytes)
def decrypt(self, ciphertext):
AES.decrypt(self, ciphertext)
ciphertextBytes = stringToBytes(ciphertext)
chainBytes = stringToBytes(self.IV)
#CBC Mode: For each block...
for x in range(len(ciphertextBytes)/16):
#Decrypt it
blockBytes = ciphertextBytes[x*16 : (x*16)+16]
blockString = bytesToString(blockBytes)
decryptedBytes = stringToBytes(self.rijndael.decrypt(blockString))
#XOR with the chaining block and overwrite the input with output
for y in range(16):
decryptedBytes[y] ^= chainBytes[y]
ciphertextBytes[(x*16)+y] = decryptedBytes[y]
#Set the next chaining block
chainBytes = blockBytes
self.IV = bytesToString(chainBytes)
return bytesToString(ciphertextBytes)
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