First commands with basic structure.

- Moves DBManager to common.

watchtower-plugin/keys.py

@@ -0,0 +1,94 @@
+import os.path
+from pathlib import Path
+from binascii import hexlify
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import ec
+
+from exceptions import InvalidKey
+from common.cryptographer import Cryptographer
+
+
+def save_key(sk, filename):
+    """
+    Saves secret key on disk.
+
+    Args:
+        sk (:obj:`PrivateKey`): a private key file to be saved on disk.
+        filename (:obj:`str`): the name that will be given to the key file.
+    """
+
+    der = sk.private_bytes(
+        encoding=serialization.Encoding.DER,
+        format=serialization.PrivateFormat.PKCS8,
+        encryption_algorithm=serialization.NoEncryption(),
+    )
+
+    with open(filename, "wb") as der_out:
+        der_out.write(der)
+
+
+def generate_keys(data_dir):
+    """
+    Generates a key pair for the client.
+
+    Args:
+        data_dir (:obj:`str`): path to data directory where the keys will be stored.
+
+    Returns:
+        :obj:`tuple`: a tuple containing a ``PrivateKey`` and a ``str`` representing the client sk and compressed
+        pk respectively.
+
+    Raises:
+        :obj:`FileExistsError`: if the key pair already exists in the given directory.
+    """
+
+    # Create the output folder it it does not exist (and all the parents if they don't either)
+    Path(data_dir).mkdir(parents=True, exist_ok=True)
+    sk_file_name = os.path.join(data_dir, "cli_sk.der")
+
+    if os.path.exists(sk_file_name):
+        raise FileExistsError("The client key pair already exists")
+
+    sk = ec.generate_private_key(ec.SECP256K1, default_backend())
+    save_key(sk, sk_file_name)
+
+    compressed_pk = sk.public_key().public_bytes(
+        encoding=serialization.Encoding.X962, format=serialization.PublicFormat.CompressedPoint
+    )
+
+    return sk, hexlify(compressed_pk).decode("utf-8")
+
+
+def load_keys(data_dir):
+    """
+    Loads a the client key pair.
+
+    Args:
+        data_dir (:obj:`str`): path to data directory where the keys are stored.
+
+    Returns:
+        :obj:`tuple`: a tuple containing a ``PrivateKey`` and a ``str`` representing the client sk and compressed
+        pk respectively.
+
+    Raises:
+        :obj:`InvalidKey <cli.exceptions.InvalidKey>`: if any of the keys is invalid or cannot be loaded.
+    """
+
+    if not isinstance(data_dir, str):
+        raise ValueError("Invalid data_dir. Please check your settings")
+
+    sk_file_path = os.path.join(data_dir, "cli_sk.der")
+
+    cli_sk_der = Cryptographer.load_key_file(sk_file_path)
+    cli_sk = Cryptographer.load_private_key_der(cli_sk_der)
+
+    if cli_sk is None:
+        raise InvalidKey("Client private key is invalid or cannot be parsed")
+
+    compressed_cli_pk = Cryptographer.get_compressed_pk(cli_sk.public_key)
+
+    if compressed_cli_pk is None:
+        raise InvalidKey("Client public key cannot be loaded")
+
+    return cli_sk, compressed_cli_pk