argon2-cffi/docs/api.rst
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API Reference
=============
.. module:: argon2
*argon2-cffi* comes with an high-level API and uses the officially recommended low-memory Argon2 parameters that result in a verification time of 40--50ms on recent-ish hardware.
.. warning::
The current memory requirement is set to rather conservative 64 MB.
However, in memory constrained environments such as Docker containers that can lead to problems.
One possible non-obvious symptom are apparent freezes that are caused by swapping.
Please check :doc:`parameters` for more details.
Unless you have any special needs, all you need to know is:
.. doctest::
>>> from argon2 import PasswordHasher
>>> ph = PasswordHasher()
>>> hash = ph.hash("correct horse battery staple")
>>> hash # doctest: +SKIP
'$argon2id$v=19$m=65536,t=3,p=4$MIIRqgvgQbgj220jfp0MPA$YfwJSVjtjSU0zzV/P3S9nnQ/USre2wvJMjfCIjrTQbg'
>>> ph.verify(hash, "correct horse battery staple")
True
>>> ph.check_needs_rehash(hash)
False
>>> ph.verify(hash, "Tr0ub4dor&3")
Traceback (most recent call last):
...
argon2.exceptions.VerifyMismatchError: The password does not match the supplied hash
A login function could thus look like this:
.. literalinclude:: login_example.py
:language: python
----
While the :class:`PasswordHasher` class has the aspiration to be good to use out of the box, it has all the parametrization you'll need:
.. autoclass:: PasswordHasher
:members: from_parameters, hash, verify, check_needs_rehash
If you don't specify any parameters, the following constants are used:
.. data:: DEFAULT_RANDOM_SALT_LENGTH
.. data:: DEFAULT_HASH_LENGTH
.. data:: DEFAULT_TIME_COST
.. data:: DEFAULT_MEMORY_COST
.. data:: DEFAULT_PARALLELISM
They are taken from :data:`argon2.profiles.RFC_9106_LOW_MEMORY`.
Profiles
--------
.. automodule:: argon2.profiles
You can try them out using the :doc:`cli` interface.
For example:
.. code-block:: console
$ python -m argon2 --profile RFC_9106_HIGH_MEMORY
Running Argon2id 100 times with:
hash_len: 32 bytes
memory_cost: 2097152 KiB
parallelism: 4 threads
time_cost: 1 iterations
Measuring...
866.5ms per password verification
That should give you a feeling on how they perform in *your* environment.
.. data:: RFC_9106_HIGH_MEMORY
Called "FIRST RECOMMENDED option" by `RFC 9106`_.
Requires beefy 2 GiB, so be careful in memory-contrained systems.
.. versionadded:: 21.2.0
.. data:: RFC_9106_LOW_MEMORY
Called "SECOND RECOMMENDED option" by `RFC 9106`_.
The main difference is that it only takes 64 MiB of RAM.
The values from this profile are the default parameters used by :class:`argon2.PasswordHasher`.
.. versionadded:: 21.2.0
.. data:: PRE_21_2
The default values that *argon2-cffi* used from 18.2.0 until 21.2.0.
Needs 100 MiB of RAM.
.. versionadded:: 21.2.0
.. data:: CHEAPEST
This is the cheapest-possible profile.
.. warning::
This is only for testing purposes!
Do **not** use in production!
.. versionadded:: 21.2.0
.. _`RFC 9106`: https://www.rfc-editor.org/rfc/rfc9106.html
Exceptions
----------
.. autoexception:: argon2.exceptions.VerificationError
.. autoexception:: argon2.exceptions.VerifyMismatchError
.. autoexception:: argon2.exceptions.HashingError
.. autoexception:: argon2.exceptions.InvalidHash
Utilities
---------
.. autofunction:: argon2.extract_parameters
.. autoclass:: argon2.Parameters
Low Level
---------
.. automodule:: argon2.low_level
.. autoclass:: Type
:members: D, I, ID
.. autodata:: ARGON2_VERSION
.. autofunction:: hash_secret
.. doctest::
>>> import argon2
>>> argon2.low_level.hash_secret(
... b"secret", b"somesalt",
... time_cost=1, memory_cost=8, parallelism=1, hash_len=64, type=argon2.low_level.Type.D
... )
b'$argon2d$v=19$m=8,t=1,p=1$c29tZXNhbHQ$ba2qC75j0+JAunZZ/L0hZdQgCv+tOieBuKKXSrQiWm7nlkRcK+YqWr0i0m0WABJKelU8qHJp0SZzH0b1Z+ITvQ'
.. autofunction:: verify_secret
The raw hash can also be computed:
.. autofunction:: hash_secret_raw
.. doctest::
>>> argon2.low_level.hash_secret_raw(
... b"secret", b"somesalt",
... time_cost=1, memory_cost=8, parallelism=1, hash_len=8, type=argon2.low_level.Type.D
... )
b'\xe4n\xf5\xc8|\xa3>\x1d'
The super low-level ``argon2_core()`` function is exposed too if you need access to very specific options:
.. autofunction:: core
In order to use :func:`core`, you need access to *argon2-cffi*'s FFI objects.
Therefore it is OK to use ``argon2.low_level.ffi`` and ``argon2.low_level.lib`` when working with it:
.. doctest::
>>> from argon2.low_level import ARGON2_VERSION, Type, core, ffi, lib
>>> pwd = b"secret"
>>> salt = b"12345678"
>>> hash_len = 8
>>> # Make sure you keep FFI objects alive until *after* the core call!
>>> cout = ffi.new("uint8_t[]", hash_len)
>>> cpwd = ffi.new("uint8_t[]", pwd)
>>> csalt = ffi.new("uint8_t[]", salt)
>>> ctx = ffi.new(
... "argon2_context *", dict(
... version=ARGON2_VERSION,
... out=cout, outlen=hash_len,
... pwd=cpwd, pwdlen=len(pwd),
... salt=csalt, saltlen=len(salt),
... secret=ffi.NULL, secretlen=0,
... ad=ffi.NULL, adlen=0,
... t_cost=1,
... m_cost=8,
... lanes=1, threads=1,
... allocate_cbk=ffi.NULL, free_cbk=ffi.NULL,
... flags=lib.ARGON2_DEFAULT_FLAGS,
... )
... )
>>> ctx
<cdata 'struct Argon2_Context *' owning 120 bytes>
>>> core(ctx, Type.D.value)
0
>>> out = bytes(ffi.buffer(ctx.out, ctx.outlen))
>>> out
b'\xb4\xe2HjO\x14d\x9b'
>>> out == argon2.low_level.hash_secret_raw(pwd, salt, 1, 8, 1, 8, Type.D)
True
All constants and types on ``argon2.low_level.lib`` are guaranteed to stay as long they are not altered by Argon2 itself.
.. autofunction:: error_to_str
Deprecated APIs
---------------
These APIs are from the first release of *argon2-cffi* and proved to live in an unfortunate mid-level.
On one hand they have defaults and check parameters but on the other hand they only consume byte strings.
Therefore the decision has been made to replace them by a high-level (:class:`argon2.PasswordHasher`) and a low-level (:mod:`argon2.low_level`) solution.
There are no immediate plans to remove them though.
.. autofunction:: argon2.hash_password
.. autofunction:: argon2.hash_password_raw
.. autofunction:: argon2.verify_password