diff --git a/ciphers/elgamal_key_generator.py b/ciphers/elgamal_key_generator.py new file mode 100644 index 000000000..6a8751f69 --- /dev/null +++ b/ciphers/elgamal_key_generator.py @@ -0,0 +1,63 @@ +import os +import random +import sys +import rabin_miller as rabinMiller, cryptomath_module as cryptoMath + +min_primitive_root = 3 + + +def main(): + 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: + 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): + 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): + 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) + 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])) + + 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])) + + +if __name__ == '__main__': + main() + \ No newline at end of file