[암호 프로그래밍] RSA를 이용한 암/복호화 , 서명

RSA 를 이용한 암/복호화

from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
import os
import sys


def main():

    mymsg = "samsjang loves python"

    prikey = RSA.generate(1024)
    pubkey = prikey.publickey()

    priPemFile = 'prikey.pem'
    pubPemFile = 'pubkey.pem'

    if os.path.exists(priPemFile) and os.path.exists(pubPemFile):
        print('[ OK ] key file exists.')
    else:
        createPEM(prikey, pubkey, priPemFile, pubPemFile)

    encMSg = rsaEnc(mymsg, pubPemFile)
    decMsg = rsaDec(encMSg, priPemFile)

    print(mymsg)
    print(encMSg)
    print(decMsg)
    pass


def rsaEnc(mymsg, file):
    return PKCS1_OAEP.new(readPem(file)).encrypt(mymsg.encode())


def rsaDec(encMsg, file):
    return PKCS1_OAEP.new(readPem(file)).decrypt(encMsg).decode()


def readPem(f):
    readPem = open(f, 'rb')
    pubkey = RSA.import_key(readPem.read())
    readPem.close()
    return pubkey


def createPEM(prikey, pubkey, priPemFile, pubPemFile):
    # input    : prikey , pubkey
    # output   : file(prikey.pem) , file(pubkey.pem)
    with open(priPemFile, 'wb') as priFile:
        priFile.write(prikey.export_key('PEM'))

    with open(pubPemFile, 'wb') as pubFile:
        pubFile.write(pubkey.export_key('PEM'))


if __name__ == '__main__':
    main()

 

RSA 를 이용한 서명

# 사전 준비 : private.pem 파일이 미리 필요하다

from Crypto.Signature import pkcs1_15
from Crypto.PublicKey import RSA
from Crypto.Hash import SHA256 as SHA


def readPEM(pemfile):
    h = open(pemfile, 'r')
    key = RSA.importKey(h.read())
    h.close()

    return key


def rsa_sign(msg):
    private_key = readPEM('prikey.pem')
    public_key = private_key.publickey()
    h = SHA.new(msg)
    signature = pkcs1_15.new(private_key).sign(h)

    return public_key, signature


def rsa_verify(msg, public_key, signature):
    h = SHA.new(msg)

    try:
        pkcs1_15.new(public_key).verify(h, signature)
        print('Authentic')
    except Exception as e:
        print('Error :', e)
        print('Not Authentic')


def main():
    #
    # Sender
    #
    msg = b'My name is samsjang'
    public_key, signature = rsa_sign(msg)

    #
    # Receiver
    #
    recv_msg = msg
    recv_pubkey = public_key
    recv_sign = signature
    rsa_verify(recv_msg, recv_pubkey, recv_sign)


if __name__ == '__main__':
    main()