Python3：试图将 b' ' 字符串解码为 ascii

Question

I'm trying to decrypt a OTP. The key is generated with the following code:

class OTPGenerator(metaclass=Singleton):
_OTP_LEN = 128

def __init__(self):
    self.otp = os.urandom(OTPGenerator._OTP_LEN)

def get_otp(self):
    return self.otp

I get receive the encrypted text thru a socket connection:

b'7Vf\xba\xe1\xb1.\xeb\x05Y\xccL 1\xb2\xec\xb1<0\xb36\xce\xc3\x02\xd6^\xc6z\x15_\x88\x14k\xe9\x8c\xb1\xa5{\xd5\xe3LKE8\x16\xe2\xe1\xf0\xe1+[_\xd47\x13\xd8T\xa7E\x8f\xf3SR\xd1'

And another encrypted text given by be as plaintext:

input = flag
Encrypted Input: b'\t\x17J\x9c'

I'm trying to decode them before XOR-ing them, but they are casted as strings.

Has anyone encountered a similar issue before?

Answer 1

The os.urandom module produces N random bytes with N being passed as argument. In that sense, I'm not sure what you want to decode since this is random data.

In any way, there is this answer that might be what you are looking for, which converts the data produce by os.urandom into a base64 encoded string.

from base64 import b64encode
from os import urandom

random_bytes = urandom(64)
token = b64encode(random_bytes).decode('utf-8')