cryprography_encryption_rsa.py

# Generating a key
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.asymmetric import rsa
private_key = rsa.generate_private_key(
        public_exponent=65537,
        key_size=1024,
        backend=default_backend()
    )

public_key = private_key.public_key()

# Storing the keys
from cryptography.hazmat.primitives import serialization
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:
    print(pem)
    f.write(pem)

pem = public_key.public_bytes(
        encoding=serialization.Encoding.PEM,
        format=serialization.PublicFormat.SubjectPublicKeyInfo
    )

with open('public_key.pem', 'wb') as f:
    print(pem)
    f.write(pem)


# Reading the keys back in (for demonstration purposes)
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import serialization
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()
        )


print(public_key)
print(private_key)

# Encrypting and decrypting
import base64
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric import padding

message = b'Encrypt my message'
encrypted = public_key.encrypt(
        message,
        padding.OAEP(
            mgf=padding.MGF1(algorithm=hashes.SHA256()),
            algorithm=hashes.SHA256(),
            label=None
        )
    )
print(encrypted)
print(base64.b64encode(encrypted).decode('ascii'))

original_message = private_key.decrypt(
        encrypted,
        padding.OAEP(
            mgf=padding.MGF1(algorithm=hashes.SHA256()),
            algorithm=hashes.SHA256(),
            label=None
        )
    )
print(original_message)