Posts
Writeups
Cancel

Given source file from Crypto.Cipher import AES import hashlib import secrets def header(): print(""" _____ _ __ __ _ | __ \(_)/ _|/ _(_) | | | |_| |_| |_ _ ___ | | | | | _| _| ...

This is an easy challenge. The prime is small so we can just brute force it. Just run through every possible int from 1 to p, square them and check if there are equal to the numbers. If they are th...

This makes you create a function to calculate if a number is a quadratic root faster. The math is pretty simple so here is the code for the function. NB: since pow() returns a positive interger and...

Source code from Crypto.Cipher import AES KEY = ? FLAG = ? @chal.route('/lazy_cbc/encrypt/<plaintext>/') def encrypt(plaintext): plaintext = bytes.fromhex(plaintext) if len(plain...

Common modulus attack In this case imagine that Alice sent the SAME message more than once using the same public key but thanks to the laws of the world, a problem happened and the public key chan...

Hastad Attack Let’s go over the math of the attack: Assume Bob sends the same message to multiple people using RSA with different modulus but the same e for all of the messages. Assume that this ...

We see that there is a form. At the bottom we can see the username we are supposed to use. It doesn’t take a genius to see that the password is most likely the flag. While testing we see that we c...

Source code and output #!/usr/bin/env python3 from Crypto.Util.number import * from hashlib import sha1 from Crypto.Cipher import AES from Crypto.Util.Padding import pad from secret import flag, n...