ssh_keygen_rsa.py

#!/usr/bin/env python3

import argparse
from Crypto.PublicKey import RSA
from Crypto import Random
import sys


def createKeys(bits=2048):
    rnd = Random.new()
    RSAkey = RSA.generate(bits, rnd.read)
    passphrase = rnd.read(128)
    privateKey = RSAkey.exportKey('PEM', passphrase=passphrase)
    publicKey = RSAkey.publickey().exportKey('PEM', passphrase=passphrase)
    return privateKey.decode('utf-8'), publicKey.decode('utf-8')


def parseargs(a):
    parser = argparse.ArgumentParser()
    parser.add_argument('--bits', type=int, default=2048)
    parser.add_argument('--file')
    return parser.parse_args()

if __name__ == '__main__':
    params = parseargs(sys.argv)
    pri, pub = createKeys(params.bits)
    try:
        open(params.file, 'w', encoding='utf-8').write(pri + '\n')
        open(params.file + '.pub', 'w', encoding='utf-8').write(pub + '\n')
    except Exception as e:
        print(e)
        sys.exit(1)