.. module: sha3


****************
SHA3 secure hash
****************

This module implements the interface to NIST’s secure hash algorithm, known as SHA-3. 
It is used in the same way as all crypto hash modules: an instance of the SHA3 class is
created, then feed this object with arbitrary strings/bytes using the update() method, and at any point you can ask it for the digest of the
concatenation of the strings fed to it so far.

The class supports 4 variants of SHA3, selectable in the constructor with one of the following constants:

    * :samp:`SHA224`
    * :samp:`SHA256`
    * :samp:`SHA284`
    * :samp:`SHA512`

The module is based on the C library `cifra <https://github.com/ctz/cifra>`_.
==============
The SHA3 class
==============
    
.. class:: SHA3(hashtype=SHA256)

       This class allows the generation of SHA3 hashes. It is thread safe. By default, it calculates the SHA256 variant
       of SHA3. This behaviour can be changed by passing a different value for *hashtype*
    
.. method:: update(data)

    Update the sha object with the string *data*. Repeated calls are equivalent to a single call with the concatenation of all
    the arguments: m.update(a); m.update(b) is equivalent to m.update(a+b).
        
.. method:: digest()

    Return the digest of the strings passed to the update method so far. This is a byte object with length depending on
    the SHA3 variant.
        
.. method:: hexdigest()

    Like digest except the digest is returned as a string containing only hexadecimal digits.