Supported Platforms

Passlib requires Python 2 (>= 2.6) or Python 3 (>= 3.3). It is known to work with the following Python implementations:


Passlib 1.8 will drop support for Python 2.x, 3.3, and 3.4; and will require Python >= 3.5. The 1.7 series will be the last to support Python 2. (See issue 119 for rationale).

  • CPython 2 – v2.6 or newer.
  • CPython 3 – v3.3 or newer.
  • PyPy – v2.0 or newer.
  • PyPy3 – v5.3 or newer.
  • Jython – v2.7 or newer.

Passlib should work with all operating systems and environments, as it contains builtin fallbacks for almost all OS-dependant features. Google App Engine is supported as well.

Changed in version 1.7: Support for Python 2.5, 3.0-3.2 was dropped. Support for PyPy 1.x was dropped.

Optional Libraries

  • bcrypt, py-bcrypt, or bcryptor


    Support for py-bcrypt and bcryptor will be dropped in Passlib 1.8, as these libraries are unmaintained.

    If any of these packages are installed, they will be used to provide support for the BCrypt hash algorithm. This is required if you want to handle BCrypt hashes, and your OS does not provide native BCrypt support via stdlib’s crypt (which includes pretty much all non-BSD systems).

    bcrypt is currently the recommended option – it’s actively maintained, and compatible with both CPython and PyPy.

    Use pip install passlib[bcrypt] to get the recommended bcrypt setup.

  • argon2_cffi (>= 18.2.0), or argon2pure (>= 1.3)

    If any of these packages are installed, they will be used to provide support for the argon2 hash algorithm. argon2_cffi is currently the recommended option.

    Use pip install passlib[argon2] to get the recommended argon2 setup.

  • Cryptography

    If installed, will be used to enable encryption of TOTP secrets for storage (see passlib.totp).

    Use pip install passlib[totp] to get the recommended TOTP setup.

  • fastpbkdf2

    If installed, will be used to greatly speed up pbkdf2_hmac(), and any pbkdf2-based hashes.

  • SCrypt (>= 0.6)

    If installed, this will be used to provide support for the scrypt hash algorithm. If not installed, a MUCH slower builtin reference implementation will be used.

Changed in version 1.7: Added fastpbkdf2, cryptography, argon2_cffi, argon2pure, and scrypt support. Removed M2Crypto support.

Installation Instructions


All PyPI releases are signed with the gpg key 4D8592DF4CE1ED31.

To install from PyPi using pip:

pip install passlib

To install from the source using

python install


Passlib contains a comprehensive set of unittests (about 38% of the total code), which provide nearly complete coverage, and verification of the hash algorithms using multiple external sources (if detected at runtime).

All unit tests are contained within the passlib.tests subpackage, and are designed to be run using the Nose unit testing library (as well as the unittest2 library under Python 2.6).

Once Passlib and Nose have been installed, the main suite of tests may be run using:

nosetests --tests passlib.tests

By default, this runs the main battery of tests, but omits some additional ones (such as internal cross-checks, and mock-testing of features not provided natively by the host OS). To run these tests as well, set the following environmental variable:

PASSLIB_TEST_MODE="full" nosetests --tests passlib.tests

To run a quick check to confirm just basic functionality, with a pared-down set of tests:

PASSLIB_TEST_MODE="quick" nosetests --tests passlib.tests

Tests may also be run via test or the included tox.ini file. The tox.ini file is used to test passlib before each release, and contains a number different environment setups. These tests require tox 2.5 or later.

Building the Documentation

The latest copy of this documentation should always be available online at If you wish to generate your own copy of the documentation, you will need to:

  1. Download the Passlib source, extract it, and cd into the source directory.
  2. Install all the dependencies required via pip install -e .[build_docs].
  3. Run python build_sphinx.
  4. Once Sphinx completes its run, point a web browser to the file at SOURCE/build/sphinx/html/index.html to access the Passlib documentation in html format.