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 public 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
- Past CTF Primes method
- Self-Initializing Quadratic Sieve (SIQS) using Yafu
- Common factor attacks across multiple keys
- Small fractions method when p/q is close to a small fraction
- Boneh Durfee Method when the private exponent d is too small compared to the modulus (i.e d < n^0.292)
- Elliptic Curve Method
usage: RsaCtfTool.py [-h] (--publickey PUBLICKEY | --createpub | --dumpkey) [--uncipher UNCIPHER] [--verbose] [--private] [--n N] [--e E] [--ecmdigits DIGITS] [--key KEY]
Mode 1 - Attack RSA (specify --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 (specify --createpub)
- n - modulus
- e - public exponent
Mode 3 - Dump the public and/or private numbers from a PEM/DER format public or private key (specify --dumpkey)
- key - the public or private key in PEM or DER format
./RsaCtfTool.py --publickey ./key.pub --uncipher ./ciphered\_file
./RsaCtfTool.py --publickey ./key.pub --private
Attempt to break multiple public keys with common factor attacks or individually - use quotes around wildcards to stop bash expansion
./RsaCtfTool.py --publickey "*.pub" --private
./RsaCtfTool.py --createpub --n 7828374823761928712873129873981723...12837182 --e 65537
./RsaCtfTool.py --dumpkey --key ./key.pub
./RsaCtfTool.py --publickey key.pub --ecmdigits 25 --verbose --private
- 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
- pastctfprimes.pub : public key with a prime from a past CTF
- siqs.pub: 256bit public key that is factored in 30 seconds with SIQS
- factordb_parsing.pub: a public key with a prime that is described as an expression on factordb.com
- smallfraction.pub: a public key where p/q is close to a small fraction
- boneh_durfee.pub: a public key factorable using boneh_durfee method
- multikey-0.pub and multikey-1.pub: Public keys that share a common factor
- ecm_method.pub: Public key with a 25 digit prime factorable with ECM method in around 2 minutes (use --ecmdigits 25 to test)
- GMPY
- SymPy
- libnum (https://github.com/hellman/libnum.git)
- PyCrypto
- Requests
- SageMath - optional but advisable
If pip install -r "requirements.txt"
fails to install requirements accessible within environment, the following command may work.
easy_install `cat requirements.txt`
- Implement multiple ciphertext handling for more attacks
- 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
- Pollards p-1 for relatively smooth numbers
- Replicate all functionality of rsatool.py
- Support more types of expression based primes from factordb.com?