[SIGINT CTF] RSA

	#!/usr/bin/env python
	from time import time
	from os import system
	from Crypto.PublicKey import RSA
	SEED = int(time())
	def randfunc(n):
	def rand():
	global SEED
	ret = SEED*0x1333370023004200babe004141414100e9a1192355de965ab8cc1239cf015a4e35 + 1
	SEED = ret
	return (ret >> 0x10) & 0x7fff
	ret = ""
	while len(ret) < n:
	ret += chr(rand() & 0xff)
	return ret
	keypair = RSA.generate(1024, randfunc)
	with open("pub", "w") as pubfile, open("id_rsa", "w") as privfile:
	privfile.write(keypair.exportKey())
	pubfile.write(keypair.publickey().exportKey())
	system("ssh-keygen -m PKCS8 -i -f pub > id_rsa.pub && rm pub")

view raw genrsa.py hosted with ❤ by GitHub

	#!/usr/bin/python
	import sys
	import base64
	import struct
	filename = sys.argv[1]
	file_contents = open(filename,'rb').read()
	base64_encoded_info = file_contents.split(' ')[1]
	raw_bytes = base64.b64decode(base64_encoded_info)
	length = struct.unpack('>I',raw_bytes[0:4])[0]
	raw_bytes = raw_bytes[4:]
	data = raw_bytes[0:length]
	print 'Obtained string: %s'%(data)
	raw_bytes = raw_bytes[length:]
	exponent_size = struct.unpack('>I',raw_bytes[0:4])[0]
	print 'Exponent size: %d'%(exponent_size)
	raw_bytes = raw_bytes[4:]
	exponent = 0
	for i in range(0,exponent_size):
	exponent<<=8
	exponent += ord(raw_bytes[i])
	print 'Exponent: '+str(exponent)
	raw_bytes = raw_bytes[exponent_size:]
	modulus_size = struct.unpack('>I',raw_bytes[0:4])[0]
	raw_bytes = raw_bytes[4:]
	print 'Modulus size: %d'%(modulus_size)
	modulus = 0
	for i in range(0,modulus_size):
	modulus<<=8
	modulus += ord(raw_bytes[i])
	print 'Modulus: '+str(modulus)

view raw rsa_extract.py hosted with ❤ by GitHub

	from Crypto.PublicKey import pubkey
	from Crypto.Util import number
	import fractions
	import sys
	MIN_SEED = int(sys.argv[1])
	MAX_SEED = int(sys.argv[2])
	SEED = MAX_SEED
	def randfunc(n):
	def rand():
	global SEED
	ret = SEED*0x1333370023004200babe004141414100e9a1192355de965ab8cc1239cf015a4e35 + 1
	SEED = ret
	return (ret >> 0x10) & 0x7fff
	ret = ""
	while len(ret) < n:
	ret += chr(rand() & 0xff)
	return ret
	correct_modulus = 133542334266816908873627788991135098836872531174929294246169531210661376429243860064170039541966242804413057715139822380296022355504905790916703933165069728724833411797448828615450127927989084469577103148831167203596018572102137170380105783557008648639360019823792278259940952368577709045086814405497576841683
	e = long(65537)
	bits = 1024
	debug = 1
	while MAX_SEED > MIN_SEED:
	SEED = MAX_SEED
	p = q = 1L
	while number.size(p*q) < bits:
	p = pubkey.getStrongPrime(bits>>1, e, 1e-12, randfunc)
	q = pubkey.getStrongPrime(bits - (bits>>1), e, 1e-12, randfunc)
	modulus = p*q
	gcd = fractions.gcd( modulus, correct_modulus )
	if gcd > 1:
	print 'GCD: %d\np: %d\nq: %d\n'%(gcd,p,q)
	break
	MAX_SEED-=1

view raw pwn_rsa.py hosted with ❤ by GitHub

	from Crypto.PublicKey import pubkey
	from Crypto.Util import number
	from Crypto.PublicKey import RSA
	from Crypto.PublicKey import _slowmath
	import fractions
	import sys
	import os
	e = long(65537)
	p = long(13097286606179453667665592444299109782484218865253457545521978739889248320232481682880143106432871469494586765663594908396375009598486558938138835723794021)
	q = long(10196183246368760603869192593971202143897281417220455881063414616103901438182656326076501376638806928762094749150020638960102206987607293047096627515275223)
	n = long(p*q)
	d = long(pubkey.inverse(e, (p-1)*(q-1)))
	key = _slowmath._RSAKey()
	key.e = e
	key.p = p
	key.q = q
	key.n = n
	key.d = d
	keypair = RSA._RSAobj(RSA.RSAImplementation(),key)
	with open("pub", "w") as pubfile, open("id_rsa", "w") as privfile:
	privfile.write(keypair.exportKey())
	pubfile.write(keypair.publickey().exportKey())
	os.system("ssh-keygen -m PKCS8 -i -f pub > id_rsa.pub && rm pub")

view raw key_gen.py hosted with ❤ by GitHub