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.. index:: Windows; NT hash
==================================================================
:class:`passlib.hash.nthash` - Windows' NT-HASH
==================================================================
.. include:: ../_fragments/trivial_hash_warning.rst
.. versionadded:: 1.6
.. currentmodule:: passlib.hash
This class implements the NT-HASH algorithm, used by Microsoft Windows NT
and successors to store user account passwords, supplanting
the much weaker :doc:`lmhash <passlib.hash.lmhash>` algorithm.
This class can be used directly as follows::
>>> from passlib.hash import nthash
>>> # hash password
>>> h = nthash.hash("password")
>>> h
'8846f7eaee8fb117ad06bdd830b7586c'
>>> # verify password
>>> nthash.verify("password", h)
True
>>> nthash.verify("secret", h)
False
.. seealso:: the generic :ref:`PasswordHash usage examples <password-hash-examples>`
Interface
=========
.. autoclass:: nthash()
Format & Algorithm
==================
A nthash consists of 32 hexadecimal digits, which encode the digest.
An example hash (of ``password``) is ``8846f7eaee8fb117ad06bdd830b7586c``.
The digest is calculated by encoding the secret using ``UTF-16-LE``,
taking the MD4 digest, and then encoding
that as hexadecimal.
FreeBSD Variant
===============
For cross-compatibility, FreeBSD's :func:`!crypt` supports storing
NTHASH digests in a manner compatible with the :ref:`modular-crypt-format`,
to enable administrators to store user passwords in a manner compatible with
the SMB/CIFS protocol. This is accomplished by assigning NTHASH digests the
identifier ``$3$``, and prepending the identifier to the normal (lowercase)
NTHASH digest. An example digest (of ``password``) is
``$3$$8846f7eaee8fb117ad06bdd830b7586c`` (note the doubled ``$$``).
.. data:: bsd_nthash
This object supports FreeBSD's representation of NTHASH
(which is compatible with the :ref:`modular-crypt-format`),
and follows the :ref:`password-hash-api`.
It has no salt and a single fixed round.
The :meth:`~passlib.ifc.PasswordHash.hash` and :meth:`~passlib.ifc.PasswordHash.genconfig` methods accept no optional keywords.
.. versionchanged:: 1.6
This hash was named ``nthash`` under previous releases of Passlib.
Security Issues
===============
This algorithm should be considered *completely* broken:
* It has no salt.
* The MD4 message digest has been severely compromised by collision and
preimage attacks.
* Brute-force and pre-computed attacks exist targeting MD4 hashes in general,
and the encoding used by NTHASH in particular.
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