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EDIT :: pysqlcipher.py

# sqlite/pysqlcipher.py # Copyright (C) 2005-2021 the SQLAlchemy authors and contributors # <see AUTHORS file> # # This module is part of SQLAlchemy and is released under # the MIT License: http://www.opensource.org/licenses/mit-license.php """ .. dialect:: sqlite+pysqlcipher :name: pysqlcipher :dbapi: pysqlcipher :connectstring: sqlite+pysqlcipher://:passphrase/file_path[?kdf_iter=<iter>] :url: https://pypi.python.org/pypi/pysqlcipher ``pysqlcipher`` is a fork of the standard ``pysqlite`` driver to make use of the `SQLCipher <https://www.zetetic.net/sqlcipher>`_ backend. ``pysqlcipher3`` is a fork of ``pysqlcipher`` for Python 3. This dialect will attempt to import it if ``pysqlcipher`` is non-present. .. versionadded:: 1.1.4 - added fallback import for pysqlcipher3 .. versionadded:: 0.9.9 - added pysqlcipher dialect Driver ------ The driver here is the `pysqlcipher <https://pypi.python.org/pypi/pysqlcipher>`_ driver, which makes use of the SQLCipher engine. This system essentially introduces new PRAGMA commands to SQLite which allows the setting of a passphrase and other encryption parameters, allowing the database file to be encrypted. `pysqlcipher3` is a fork of `pysqlcipher` with support for Python 3, the driver is the same. Connect Strings --------------- The format of the connect string is in every way the same as that of the :mod:`~sqlalchemy.dialects.sqlite.pysqlite` driver, except that the "password" field is now accepted, which should contain a passphrase:: e = create_engine('sqlite+pysqlcipher://:testing@/foo.db') For an absolute file path, two leading slashes should be used for the database name:: e = create_engine('sqlite+pysqlcipher://:testing@//path/to/foo.db') A selection of additional encryption-related pragmas supported by SQLCipher as documented at https://www.zetetic.net/sqlcipher/sqlcipher-api/ can be passed in the query string, and will result in that PRAGMA being called for each new connection. Currently, ``cipher``, ``kdf_iter`` ``cipher_page_size`` and ``cipher_use_hmac`` are supported:: e = create_engine('sqlite+pysqlcipher://:testing@/foo.db?cipher=aes-256-cfb&kdf_iter=64000') Pooling Behavior ---------------- The driver makes a change to the default pool behavior of pysqlite as described in :ref:`pysqlite_threading_pooling`. The pysqlcipher driver has been observed to be significantly slower on connection than the pysqlite driver, most likely due to the encryption overhead, so the dialect here defaults to using the :class:`.SingletonThreadPool` implementation, instead of the :class:`.NullPool` pool used by pysqlite. As always, the pool implementation is entirely configurable using the :paramref:`_sa.create_engine.poolclass` parameter; the :class:`.StaticPool` may be more feasible for single-threaded use, or :class:`.NullPool` may be used to prevent unencrypted connections from being held open for long periods of time, at the expense of slower startup time for new connections. """ # noqa from __future__ import absolute_import from .pysqlite import SQLiteDialect_pysqlite from ... import pool from ...engine import url as _url class SQLiteDialect_pysqlcipher(SQLiteDialect_pysqlite): driver = "pysqlcipher" pragmas = ("kdf_iter", "cipher", "cipher_page_size", "cipher_use_hmac") @classmethod def dbapi(cls): try: from pysqlcipher import dbapi2 as sqlcipher except ImportError as e: try: from pysqlcipher3 import dbapi2 as sqlcipher except ImportError: raise e return sqlcipher @classmethod def get_pool_class(cls, url): return pool.SingletonThreadPool def connect(self, *cargs, **cparams): passphrase = cparams.pop("passphrase", "") pragmas = dict((key, cparams.pop(key, None)) for key in self.pragmas) conn = super(SQLiteDialect_pysqlcipher, self).connect( *cargs, **cparams ) conn.execute('pragma key="%s"' % passphrase) for prag, value in pragmas.items(): if value is not None: conn.execute('pragma %s="%s"' % (prag, value)) return conn def create_connect_args(self, url): super_url = _url.URL( url.drivername, username=url.username, host=url.host, database=url.database, query=url.query, ) c_args, opts = super( SQLiteDialect_pysqlcipher, self ).create_connect_args(super_url) opts["passphrase"] = url.password return c_args, opts dialect = SQLiteDialect_pysqlcipher

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