wrap_openssl.py

import os
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
from cryptography.hazmat.backends.openssl import backend as openssl
from cryptography.hazmat.primitives.hashes import SHA256, SHA512
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.primitives.asymmetric.padding import PSS, OAEP, MGF1


class OpenSSLWrapper:
    backend = openssl
    def __init__(self):
        pass

    def aes_encrypt(self, s, key):
        iv = os.urandom(16)
        cipher = Cipher(algorithms.AES(key), modes.CTR(iv),
            backend=OpenSSLWrapper.backend)
        encryptor = cipher.encryptor()
        ct = encryptor.update(s) + encryptor.finalize()
        return iv + ct

    def aes_decrypt(self, s, key):
        iv = s[:16]
        cipher = Cipher(algorithms.AES(key), modes.CTR(iv),
            backend=OpenSSLWrapper.backend)
        decryptor = cipher.decryptor()
        p = decryptor.update(s[16:]) + decryptor.finalize()
        return p

    def rsa_sign(self, msg, user_pri_key):
        signer = user_pri_key.signer(
            PSS(mgf=MGF1(SHA512()),
            salt_length=PSS.MAX_LENGTH), SHA512())
        signer.update(msg)
        signature = signer.finalize()
        sig_length = (len(signature)).to_bytes(4, byteorder='big')
        return sig_length + signature + msg

    def rsa_verify(self, msg, user_pub_key):
        sig_length_bytes = msg[:4]
        sig_length = int.from_bytes(sig_length_bytes, byteorder='big')
        signature = msg[4:4+sig_length]
        s = msg[4+sig_length:]
        verifier = user_pub_key.verifier(
            signature,
            PSS(mgf=MGF1(SHA512()), salt_length=PSS.MAX_LENGTH), SHA512())
        verifier.update(s)
        verifier.verify()
        return s

    def sha256(self, msg):
        digest = hashes.Hash(SHA256(), backend=OpenSSLWrapper.backend)
        digest.update(msg)
        return digest.finalize()

    def random(self, length):
        return os.urandom(length)



class CryptoOps:

    def __init__(self, user_pri_key):
        self.openSSL = OpenSSLWrapper()

    def encrypt_sign(s, aes_key):
        c = self.openSSL.aes_encrypt(s, aes_key)
        p = openSSL.rsa_sign(c, user_pri_key)