Python/ciphers/elgamal_key_generator.py

72 lines
2.1 KiB
Python
Raw Normal View History

import os
import random
import sys
from . import cryptomath_module as cryptoMath
from . import rabin_miller as rabinMiller
min_primitive_root = 3
def main():
2019-10-05 05:14:13 +00:00
print("Making key files...")
makeKeyFiles("elgamal", 2048)
print("Key files generation successful")
# I have written my code naively same as definition of primitive root
# however every time I run this program, memory exceeded...
# so I used 4.80 Algorithm in
# Handbook of Applied Cryptography(CRC Press, ISBN : 0-8493-8523-7, October 1996)
# and it seems to run nicely!
def primitiveRoot(p_val):
print("Generating primitive root of p")
while True:
2019-10-05 05:14:13 +00:00
g = random.randrange(3, p_val)
if pow(g, 2, p_val) == 1:
continue
if pow(g, p_val, p_val) == 1:
continue
return g
def generateKey(keySize):
2019-10-05 05:14:13 +00:00
print("Generating prime p...")
p = rabinMiller.generateLargePrime(keySize) # select large prime number.
e_1 = primitiveRoot(p) # one primitive root on modulo p.
d = random.randrange(3, p) # private_key -> have to be greater than 2 for safety.
e_2 = cryptoMath.findModInverse(pow(e_1, d, p), p)
publicKey = (keySize, e_1, e_2, p)
privateKey = (keySize, d)
return publicKey, privateKey
def makeKeyFiles(name, keySize):
2019-10-05 05:14:13 +00:00
if os.path.exists("%s_pubkey.txt" % name) or os.path.exists(
"%s_privkey.txt" % name
):
print("\nWARNING:")
print(
'"%s_pubkey.txt" or "%s_privkey.txt" already exists. \n'
"Use a different name or delete these files and re-run this program."
% (name, name)
)
sys.exit()
publicKey, privateKey = generateKey(keySize)
2019-10-05 05:14:13 +00:00
print("\nWriting public key to file %s_pubkey.txt..." % name)
with open("%s_pubkey.txt" % name, "w") as fo:
fo.write(
"%d,%d,%d,%d" % (publicKey[0], publicKey[1], publicKey[2], publicKey[3])
)
2019-10-05 05:14:13 +00:00
print("Writing private key to file %s_privkey.txt..." % name)
with open("%s_privkey.txt" % name, "w") as fo:
fo.write("%d,%d" % (privateKey[0], privateKey[1]))
2019-10-05 05:14:13 +00:00
if __name__ == "__main__":
main()