*CTF 2021 | MyEnc

*ctf_2021 rsa

#*CTF_2021 from Crypto.Util.number import getPrime,bytes_to_long import time,urandom from flag import flag iv=bytes_to_long(urandom(256)) assert len(flag)==15 keystream=bin(int(flag.encode('hex'),16))[2:].rjust(8*len(flag),'0') p=getPrime(…

2023-12-11

*CTF 2021 | MyCurve

*ctf_2021 何かしらの曲線 ecdlp binary_edwards_curve isomorphism pohlig-hellman_attack

#*CTF_2021 from Crypto.Util.number import bytes_to_long from flag import flag assert flag[:5]=='*CTF{' and flag[-1]=='}' flag=flag[5:-1] def add(P,Q): if Q==0: return P x1,y1=P x2,y2=Q return (d1*(x1+x2)+d2*(x1+y1)*(x2+y2)+(x1+x1^2)*(x2*(y…

2023-12-09

*CTF 2021 | Guess Key

*ctf_2021

*CTF 2021 from random import randint import os from flag import flag import sys N=64 key=randint(0,2**N) # print key key=bin(key)[2:].rjust(N,'0') count=0 while True: zeros=[0] # indices of 0 in key for j in range(len(key)): if key[j]=='0'…

2023-11-30

*CTF 2021 | little case

*ctf_2021 boneh_durfee_attack gcd(phi,_e)_!=_1のrsa

#*CTF_2021 from Crypto.Util.number import * from libnum import * from secret import flag,special,p,q,n def little_trick(msg): p1 = getPrime(1024) q1 = getPrime(1024) n1 = p1 * q1 d1=random.randint(1,2**256) e1=inverse(d1,(p1-1)*(q1-1)) pri…