RsaCtfTool

RSA tool for ctf - uncipher data from weak public key and try to recover private key Automatic selection of best attack for the given public key

Attacks :

• Weak public key factorization
• Wiener's attack
• Hastad's attack (Small exponent attack)
• Small q (q<100,000)
• Common factor between ciphertext and modulus attack
• Fermat's factorisation for close p and q
• Gimmicky Primes method

Usage:

usage: RsaCtfTool.py [-h] (--publickey PUBLICKEY | --createpub) [--uncipher UNCIPHER] [--verbose] [--private] [--n N] [--e E]

Mode 1 - Attack RSA (specify --publickey)

• publickey : public rsa key to crack
• uncipher : cipher message to decrypt
• private : display private rsa key if recovered

Mode 2 - Create a Public Key File Given n and e (specify --createpub)

• n - modulus
• e - public exponent

Uncipher file :

./RsaCtfTool.py --publickey ./key.pub --uncipher ./ciphered_file

Print private key :

./RsaCtfTool.py --publickey ./key.pub --private

Generate a public key :

./RsaCtfTool.py --createpub --n 7828374823761928712873129873981723...12837182 --e 65537

Examples :

• weak_public.pub, weak_public.cipher : weak public key
• wiener.pub, wiener.cipher : key vulnerable to Wiener's attack
• small\exponent.pub, small_exponent.cipher : key with e=3, vulnerable to Hastad's attack
• small_q.pub, small_q.cipher : public key with a small prime
• close_primes.pub, close_primes.cipher : public key with primes suceptible to fermat factorization
• elite_primes.pub : public key with a gimmick prime
• fermat.pub : public key with another vulnerability to fermat factorization

Requirements:

• GMPY
• libnum (https://github.com/hellman/libnum.git)