pyssb/ssb/util.py

# SPDX-License-Identifier: MIT
#
# Copyright (c) 2017 PySSB contributors (see AUTHORS for more details)
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# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in all
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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"""Utility functions"""

from base64 import b64decode, b64encode
import os
from typing import Optional, TypedDict

from nacl.signing import SigningKey, VerifyKey
import yaml


class SSBSecret(TypedDict):
    """Dictionary to hold an SSB identity"""

    keypair: SigningKey
    id: str


class ConfigException(Exception):
    """Exception to raise if there is a problem with the configuration data"""


def tag(key: VerifyKey) -> bytes:
    """Create tag from public key"""

    return b"@" + b64encode(bytes(key)) + b".ed25519"


def load_ssb_secret(filename: Optional[str] = None) -> SSBSecret:
    """Load SSB keys from ``filename`` or, if unset, from ``~/.ssb/secret``"""

    filename = filename or os.path.expanduser("~/.ssb/secret")

    with open(filename, encoding="utf-8") as f:
        config = yaml.load(f, Loader=yaml.SafeLoader)

    if config["curve"] != "ed25519":
        raise ConfigException("Algorithm not known: " + config["curve"])

    server_prv_key = b64decode(config["private"][:-8])
    return {"keypair": SigningKey(server_prv_key[:32]), "id": config["id"]}