from Crypto import Random
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_v1_5
from Crypto.Hash import SHA512
from base64 import b64encode, b64decode

data_to_sign = "Secret"
data_to_verify_1 = data_to_sign
data_to_verify_2 = data_to_sign + "1"


def rsa_keys():
    length = 2048
    private_key = RSA.generate(length, Random.new().read)
    public_key = private_key.publickey()
    return private_key.exportKey('PEM'), public_key.exportKey('PEM')


def rsa_sign(private_key, data):
    digest = SHA512.new()
    digest.update(data.encode())
    signer = PKCS1_v1_5.new(private_key)
    return b64encode(signer.sign(digest))


def rsa_verify(public_key, data, sign):
    sign = b64decode(sign)
    digest = SHA512.new()
    digest.update(data.encode())
    verifier = PKCS1_v1_5.new(public_key)
    return verifier.verify(digest, sign)


def main():
    # GENERATE & EXPORT RSA KEYS
    # private_key, public_key = rsa_keys()
    # with open("public.key", 'w') as file:
    #     file.write(public_key.decode())
    # with open("private.key", 'w') as file:
    #     file.write(private_key.decode())
    # LOAD KEYS
    private_key = RSA.importKey(open("private.key", 'r').read())
    public_key = RSA.importKey(open("public.key", 'r').read())
    # CREATE SIGNATURE
    sign = rsa_sign(private_key, data_to_sign)

    # VERIFY SIGNATURE
    print("STATUS: ", end='')
    if rsa_verify(public_key, data_to_verify_1, sign):
        print("VERIFIED")
    else:
        print("FAILED")


if __name__ == '__main__':
    main()