RsaCtfTool

RsaCtfTool is a utility to uncipher data from a weak public key and try to recover the private key. Here is the list of attacks implemented in RsaCtfTool:

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
Self-Initializing Quadratic Sieve (SIQS) using Yafu
Common factor attacks across multiple keys

Installation

pip install -r requirements.txt

Usage

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

Mode 1 - Attack RSA (--publickey)

publickey : public rsa key to crack. You can import multiple public keys with wildcards.
uncipher : cipher message to decrypt
private : display private rsa key if recovered

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

n - modulus
e - public exponent

Uncipher file

python RsaCtfToolcli.py --publickey key.pub --uncipher data.cipher

Print private key

python RsaCtfToolcli.py --publickey key.pub --private

Generate a public key

python RsaCtfToolcli.py --createpub --n 7828374823761928712873129873981723 --e 65537

Todo

Implement multiple ciphertext handling for more attacks
Implement ECM factoring
Implement support for MultiPrime RSA (see 0ctf 2016)
Possibly implement Msieve support...
Some kind of polynomial search...
Brainstorm moar attack types!
Saw a CTF where the supplied N was a 2048 bit prime. Detect this and solve using phi = (n - 1) * (n - 1) which seemed to work for that CTF
Replace pycrypto dependency with cryptography.io

Tests

Find examples of code api usage and sample data in tests. Run tests:

./runtests tests/

xmunoz/RsaCtfTool