42 lines
1.1 KiB
Python
42 lines
1.1 KiB
Python
|
import secrets
|
||
|
|
|
||
|
|
def xor(a: bytes, b: bytes):
|
||
|
|
if len(a)!=len(b):
|
||
|
|
raise Exception("Bad Length")
|
||
|
|
return bytes([a[i]^b[i] for i in range(len(a))])
|
||
|
|
|
||
|
|
def cbcXor(blocks, key: bytes, iv: bytes = None, BS=16):
|
||
|
|
if len(key)!=BS:
|
||
|
|
raise Exception("Bad key len")
|
||
|
|
if not iv:
|
||
|
|
iv = secrets.token_bytes(16)
|
||
|
|
lastBlock = iv
|
||
|
|
res = []
|
||
|
|
for block in blocks:
|
||
|
|
if len(block)!=BS:
|
||
|
|
raise Exception("Bad block length")
|
||
|
|
mid = xor(block, lastBlock)
|
||
|
|
enc = xor(mid, key)
|
||
|
|
lastBlock = enc
|
||
|
|
res.append(enc)
|
||
|
|
return res
|
||
|
|
|
||
|
|
def decCbcXor(blocks, key: bytes, iv: bytes = None, BS=16):
|
||
|
|
if len(key)!=BS:
|
||
|
|
raise Exception("Bad key len")
|
||
|
|
if not iv:
|
||
|
|
iv = secrets.token_bytes(16)
|
||
|
|
lastBlock = iv
|
||
|
|
res = []
|
||
|
|
for block in blocks:
|
||
|
|
if len(block)!=BS:
|
||
|
|
raise Exception("Bad block length")
|
||
|
|
mid = xor(block, key)
|
||
|
|
enc = xor(mid, lastBlock)
|
||
|
|
lastBlock = block
|
||
|
|
res.append(enc)
|
||
|
|
return res
|
||
|
|
|
||
|
|
def randBlocks(num: int = 64):
|
||
|
|
return [secrets.token_bytes(16) for i in range(num)]
|