cryptohard

Kiss ASIS

ASIS CTF

Task: break a modified RSA with phi=(p^k-1)(q^k-1) and very large private exponent d. Solution: apply continued fraction expansion on e/N^k for k=1..6 to recover d from convergents, handling both e*d≡1 and e*d≡-1 (mod phi) cases.

$ ls tags/ techniques/

modular_inverse rsa continued_fractions lattice_attack modified_rsa wiener_variant large_private_exponent generalized_wiener

Continued fraction expansion on e/N^kConvergent enumeration for key recoveryHandling e*d ≡ -1 (mod phi) caseModular inverse decryption

Analysis

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$ python3 exploit.py --target 192.168.1.1 --port 8080
[*] Connecting to target...
[+] Shell obtained!

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