# RSA Key Generator # http://inventwithpython.com/hacking (BSD Licensed) import random, sys, os, rabinMiller, cryptomath def main(): # create a public/private keypair with 1024 bit keys print('Making key files...') makeKeyFiles('al_sweigart', 1024) print('Key files made.') def generateKey(keySize): # Creates a public/private key pair with keys that are keySize bits in # size. This function may take a while to run. # Step 1: Create two prime numbers, p and q. Calculate n = p * q. print('Generating p prime...') p = rabinMiller.generateLargePrime(keySize) print('Generating q prime...') q = rabinMiller.generateLargePrime(keySize) n = p * q # Step 2: Create a number e that is relatively prime to (p-1)*(q-1). print('Generating e that is relatively prime to (p-1)*(q-1)...') while True: # Keep trying random numbers for e until one is valid. e = random.randrange(2 ** (keySize - 1), 2 ** (keySize)) if cryptomath.gcd(e, (p - 1) * (q - 1)) == 1: break # Step 3: Calculate d, the mod inverse of e. print('Calculating d that is mod inverse of e...') d = cryptomath.findModInverse(e, (p - 1) * (q - 1)) publicKey = (n, e) privateKey = (n, d) print('Public key:', publicKey) print('Private key:', privateKey) return (publicKey, privateKey) def makeKeyFiles(name, keySize): # Creates two files 'x_pubkey.txt' and 'x_privkey.txt' (where x is the # value in name) with the the n,e and d,e integers written in them, # delimited by a comma. # Our safety check will prevent us from overwriting our old key files: if os.path.exists('%s_pubkey.txt' % (name)) or os.path.exists('%s_privkey.txt' % (name)): sys.exit('WARNING: The file %s_pubkey.txt or %s_privkey.txt already exists! Use a different name or delete these files and re-run this program.' % (name, name)) publicKey, privateKey = generateKey(keySize) print() print('The public key is a %s and a %s digit number.' % (len(str(publicKey[0])), len(str(publicKey[1])))) print('Writing public key to file %s_pubkey.txt...' % (name)) fo = open('%s_pubkey.txt' % (name), 'w') fo.write('%s,%s,%s' % (keySize, publicKey[0], publicKey[1])) fo.close() print() print('The private key is a %s and a %s digit number.' % (len(str(publicKey[0])), len(str(publicKey[1])))) print('Writing private key to file %s_privkey.txt...' % (name)) fo = open('%s_privkey.txt' % (name), 'w') fo.write('%s,%s,%s' % (keySize, privateKey[0], privateKey[1])) fo.close() # If makeRsaKeys.py is run (instead of imported as a module) call # the main() function. if __name__ == '__main__': main()