Do you wanna air my dirty laundry? How to solve Recovering PRNG The challenge uses 256-bit LFSR PRNG, of which seed is the lower 256-bit of 1024-bit prime number. Let’s see pailler_enc unction. def paillier_enc(m, p, noise): p = next_prime(p + noise) q = getStrongPrime(512) n = p * q g = (1 + prng.rand() * n) % n**2 c = pow(g, m, n**2) * pow(prng.rand(), n, n**2) % n**2 return n, g, c The value p is 1024-bit, so n should be 1536-bit....
nc 18.179.178.246 3002 (This was all of the description) Overview From the organizer’s write-up(Link): FiniteGeneralLinearGroup is just a matrix class over a finite field. We can encrypt and decrypt arbitrary messages. Encryption is defined as: $Y = UXU^{-1}$. Decryption is defined as: $X = U^{-1}YU$. The size of matrix (from the server) is 6×6. How to solve You cannot decrypt the flag directly, because it only accepts the matrix with values in the range 0~255....
I made a cipher-signature system by myself. nc 18.179.178.246 3001 How to Solve In the challenge, you can (1) encrypt and sign, (2) verify encrypted message, and (3) get public key. The public key of the server is always fixed. If you see the verify function of server.py, you can find out that it will let you know the hash of the decrypted message. if h == H: sock.send(b"Signature OK!\n") else: sock....
오늘 부산의 중국비자서비스센터에 다녀왔습니다. 안타깝게도 중국을 다녀오려면 비자가 꼭 필요하더라고요. 0CTF/TCTF 측에서 그래서 초청장을 보내왔습니다. 초청장을 갖...
The .Wat ness is open for testing! http://watness.pwni.ng:7744/ When it came out in 2016, the Witness impressed with its ability to gradually teach new players the rules of the game by simply having them play it. With the .Wat ness, we take this just a small step further. How to solve First of all, this write-up has a lot of guesses. Also, teammate imnotkind helped in downloading resources and reversing typescript files!...