Onionr/src/safedb/securestring/__init__.py

"""Onionr - Private P2P Communication

Wrap RinseOff, a c# CLI tool for secure data erasure via a keyfile.

Intended for encrypting database entries.

It is quite slow since it spawns an external process,
but an ext process is necessary to keep the key out
of memory as much as possible
"""
import os
from typing import Union

import subprocess

from filepaths import secure_erase_key_file, app_root
import logger
"""
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.
"""


_rinseoff = f"{app_root}/src/rinseoff/rinseoffcli"


def generate_key_file():
    if os.path.exists(secure_erase_key_file):
        raise FileExistsError(
            "Key file for rinseoff secure erase already exists")

    with open(secure_erase_key_file, 'wb') as f:
        f.write(os.urandom(32))


def protect_string(plaintext: Union[bytes, bytearray, str]) -> bytes:
    """Create a "secure" string. Dont really rely on this, and dont use for comms

    This is just to make forensics a little harder"""
    try:
        plaintext = plaintext.encode('utf-8')
    except AttributeError:
        pass

    process = subprocess.Popen(
                           ["dotnet", "run",
                            "--project", _rinseoff,
                            "store", "stdout", f"{secure_erase_key_file}"],
                           stdout=subprocess.PIPE,
                           stderr=subprocess.PIPE,
                           stdin=subprocess.PIPE)
    res = process.communicate(plaintext)

    if res[0] and not res[1]:
        return res[0]
    else:
        logger.warn("Error when protecting string for database", terminal=True)
        for line in res[1].decode('utf-8').split('\n'):
            logger.error(line, terminal=True)
        raise subprocess.CalledProcessError(
            "Error protecting string")


def unprotect_string(ciphertext: Union[bytes, bytearray]) -> bytes:
    process = subprocess.Popen(
                           ["dotnet", "run",
                            "--project", _rinseoff,
                            "load", "stdin", f"{secure_erase_key_file}"],
                           stdout=subprocess.PIPE,
                           stderr=subprocess.PIPE,
                           stdin=subprocess.PIPE)
    res = process.communicate(ciphertext)

    if res[0] and not res[1]:
        return res[0]
    else:
        logger.warn(
            "Error when decrypting ciphertext from database", terminal=True)
        for line in res[1].decode('utf-8').split('\n'):
            logger.error(line, terminal=True)
        raise subprocess.CalledProcessError(
            "Error unprotecting string")