rsa_extract.py

#!/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)