THCon - Crypto

Tue, 08 Apr 2025 00:00:00 +0000

Overview of the Challenge Link to heading

In this challenge we are given a Python script that performs a one-time pad (OTP) encryption on a file and a crypted file.

Here’s what happens:

1.OTP Generation: Link to heading

A 10-byte pad is generated using random bytes.

def generate_OTP():
 OTP = b''
 for _ in range(10):
 # Generates a random byte (0–255) and appends it to the OTP.
 OTP += int.to_bytes(randint(0,255), 1, 'big')
 return OTP

2.File Encryption: Link to heading

The script reads the input file in binary mode and encrypts it by XORing each byte with a corresponding byte from the OTP (repeating the OTP cyclically).

Thcon on Anthrace | CTF Writeups

THCon - Crypto

Overview of the Challenge Link to heading

1.OTP Generation: Link to heading

2.File Encryption: Link to heading