#hakatashi #TSGCTF_2021 require 'openssl' require 'digest' STDOUT.sync = true class OpenSSL::PKey::EC::Point def xy n = to_bn(:uncompressed).to_i mask = (1 << group.degree) - 1 return (n >> group.degree) & mask, n & mask end alias_method :…

#TSGCTF_2021 #hakatashi require 'openssl' require 'digest' STDOUT.sync = true class OpenSSL::PKey::EC::Point def xy n = to_bn(:uncompressed).to_i mask = (1 << group.degree) - 1 return (n >> group.degree) & mask, n & mask end alias_method :…

#TSGCTF_2021 #hakatashi # See also https://github.com/tsg-ut/pycryptodome from Crypto.PublicKey import DSA from Crypto.Signature import DSS from Crypto.Hash import SHA256 from Crypto.Util.number import getPrime from Crypto.Random.random im…

#TSGCTF_2021 #hakatashi from secret import e from Crypto.Util.number import getStrongPrime, isPrime p = getStrongPrime(1024) q = getStrongPrime(1024) N = p * q phi = (p - 1) * (q - 1) with open('flag.txt', 'rb') as f: flag = int.from_bytes…