#ECDH #InvalidCurveAttack #CRT 楕円曲線の位数がある程度小さい数を含むように素因数分解できる場合に、楕円曲線のgenerator * (order / factor)をやると、位数がfactorな部分群のgeneratorが求まる（位数を調整するテク）。あとは #CRT で復元 #!/usr/bin…

#ECDH #ECDLP """ supercurve.py An implementation of a weak elliptic curve over a prime field in standard Weirstrauss form: y^2 = x^3 + ax + b Derived from: https://github.com/andreacorbellini/ecc/blob/master/logs/common.py """ class SuperC…

#ECDH #ECDLP #Pohlig-Hellman_Attack Elliptic Curve: y^2 = x^3 + A*x + B mod M M = 93556643250795678718734474880013829509320385402690660619699653921022012489089 A = 660015981440128658766741155702689908063145067111045210367475336127984349047…

#googlectf2021 #!/usr/bin/python3 import os import hashlib from cryptography.hazmat.backends import default_backend from cryptography.hazmat.primitives import padding from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, m…

#nullconHackIM2019 https://ctftime.org/task/7528 https://gitlab.com/n0tsobad/ctf-writeups/tree/master/2019-02-01-nullcon/Singular https://grosquildu.github.io/writeups/2019/01/03/nullcon-singular/ https://crypto.stackexchange.com/questions…

#ECDH from flag import FLAG FLAG = int(FLAG.encode('hex'),16) P = 0xd3ceec4c84af8fa5f3e9af91e00cabacaaaecec3da619400e29a25abececfdc9bd678e2708a58acb1bd15370acc39c596807dab6229dca11fd3a217510258d1b A = 0x95fc77eb3119991a0022168c83eee7178e6c…

#TAMUCTF19 https://ctftime.org/task/7746 Mike, the System Administrator, thought it would be a good idea to implement his own Elliptic Curve Diffie Hellman key exchange using unnamed curves to use across the network. We managed to capture …