Using python cryptography module to generate an RSA keypair, serialize, deserialize the keys and perform encryption and decryption

rsa_encryption.py

import base64
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import padding


def utf8(s: bytes):
    return str(s, 'utf-8')


private_key = rsa.generate_private_key(
    public_exponent=65537,
    key_size=4096,
    backend=default_backend()
)
public_key = private_key.public_key()


private_pem = private_key.private_bytes(
    encoding=serialization.Encoding.PEM,
    format=serialization.PrivateFormat.PKCS8,
    encryption_algorithm=serialization.NoEncryption()
)

with open('private_key.pem', 'wb') as f:
    f.write(private_pem)

public_pem = public_key.public_bytes(
    encoding=serialization.Encoding.PEM,
    format=serialization.PublicFormat.SubjectPublicKeyInfo
)
with open('public_key.pem', 'wb') as f:
    f.write(public_pem)


with open("private_key.pem", "rb") as key_file:
    private_key = serialization.load_pem_private_key(
        key_file.read(),
        password=None,
        backend=default_backend()
    )

with open("public_key.pem", "rb") as key_file:
    public_key = serialization.load_pem_public_key(
        key_file.read(),
        backend=default_backend()
    )


plaintext = b'this is the correct plaintext!'
print(f'plaintext: \033[1;33m{utf8(plaintext)}\033[0m')
encrypted = base64.b64encode(public_key.encrypt(
    plaintext,
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
))
print(f'encrypted: \033[1;32m{utf8(encrypted)}\033[0m')


decrypted = private_key.decrypt(
    base64.b64decode(encrypted),
    padding.OAEP(
        mgf=padding.MGF1(algorithm=hashes.SHA256()),
        algorithm=hashes.SHA256(),
        label=None
    )
)
print(f'decrypted: \033[1;31m{utf8(decrypted)}\033[0m')