pwcryptolib.py 文件源码

def encrypt_with_ecc(public_ecc_key, message, nonce=None):
    """Takes elliptic curve isntance (public_ecc_key) and a byte string
    (message), and outputs a ciphertext
    """
    assert isinstance(public_ecc_key, ECC.EccKey),\
        "public_ecc_key should be ECC key. Got {}".format(type(public_ecc_key))
    random_ecc_key = ECC.generate(curve=public_ecc_key.curve)
    new_point = public_ecc_key.pointQ * random_ecc_key.d
    h = SHA256.new(str(new_point.x))
    h.update('XXX' + str(new_point.y)) # 'XXX' is a delimiter
    key = h.digest()
    if not nonce:
        nonce = os.urandom(16)
    aes_engine = AES.new(key=key, mode=AES.MODE_EAX, nonce=nonce)
    ctx, tag = aes_engine.encrypt_and_digest(message)
    # Return: <ephemeral_pub_key>, <nonce>, <ciphertext>, <tag>
    return (random_ecc_key.public_key().export_key(format='OpenSSH'),
            aes_engine.nonce, ctx, tag)