\input texinfo   @c -*-texinfo-*-
@c %**start of header
@documentencoding UTF-8
@include macros.texinfo
@copying
@c --------------------------------------------------------------------------------
Copyright @copyright{} 2015  Mattias Andrée @e{maandree@@member.fsf.org}

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version@tie{}1.3
or any later version published by the Free Software Foundation; with the
Invariant Sections being the ``GNU Affero General Public License'', the
``GNU Free Documentation License'', with no Front-Cover Texts, and with
no Back-Cover Texts. A copy of the license is included in the section
entitled ``GNU Free Documentation License''.
@end quotation
@c --------------------------------------------------------------------------------
@end copying


@setfilename libkeccak.info
@settitle libkeccak -- Library for the Keccak-family hash functions
@documentlanguage en_GB
@finalout
@frenchspacing on
@afourpaper

@c @paragraphindent asis
@c @firstparagraphindent none
@c @exampleindent asis

@dircategory Libraries
@direntry
* libkeccak: (libkeccak).       Library for the Keccak-family hash functions.
@end direntry

@documentdescription
Developer reference manual for libkeccak, a library
for hashing with Keccak, SHA-3 RawSHAKE and SHAKE,
with support for bit-oriented data.
@end documentdescription
@c %**end of header



@ifnottex
@node Top
@top libkeccak -- Library for the Keccak-family hash functions
@insertcopying
@end ifnottex

@titlepage
@title libkeccak
@subtitle Library for the Keccak-family hash functions

@author by Mattias Andrée (maandree)

@page
@center `Kecak! Kecak! Kecak! Kecak! Kecak! Kecak! Kecak! Kecak! …'
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents



@menu
* Overview::                                  Brief overview of libkeccak.
* Linking::                                   How to use libkeccak in your software.

* GNU Affero General Public License::         Copying and sharing libkeccak.
* GNU Free Documentation License::            Copying and sharing this manual.

* Concept index::                             Index of concepts.
* Data type index::                           Index of data types.
* Function index::                            Index of functions.
@end menu
@c TODO @detailmenu (`C-c C-u m`)



@node Overview
@chapter Overview

libkeccak is a free software bit-oriented implementation
of the cryptographic hash function Keccak and its subsets
SHA-3 (Secure Hash Algorithm@tie{}3), RawSHAKE and SHAKE.

Being bit-oriented means that it supports messages of length
consisting of a non-whole number of bytes.

Keccak is a generic and tunable cryptographic hash function
that can be used for all customary tasks that required a
cryptographic hash function:
@itemize @bullet{}
@item
Password verification@footnote{Using additional squeezes, but not using iterated hashing.}
@item
Proof-of-work
@item
File and data identification
@item
Data integrity
@item
Pseudorandom generation@footnote{Although not too random, since entropi is not utilised.}
@item
Key derivation
@end itemize

libkeccak support secure erasure of sensitive data,
marshalling of hashing state, and indefinite output length.
It also has builting functions for hashing files and
wrapping the hash functions with HMAC@footnote{Although
doing so is unnecessary because the key can securely be
prepended to the message when using Keccak to produce
a message authentication code.}. This library implements
the Keccak algorithm using a lanewise implementation.
libkeccak must compelling feature however is that it is
licensed under the strongest free software license:
GNU Affero General Public License version@tie{}3
(see @ref{GNU Affero General Public License},) which
gives the user the four essential freedoms:
@itemize @bullet{}
@item
The freedom to run the program as you wish, for any purpose (freedom 0).
@item
The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1).
@item
The freedom to redistribute copies so you can help your neighbor (freedom 2).
@item
The freedom to distribute copies of your modified versions to others (freedom 3).
@end itemize



@node Linking
@chapter Linking

libkeccak's API is C standard library independent. This means
that libkeccak does not need to be compiled with the same
C standard library as software using it. However, the header
files contain @code{__attributes__}:s for GCC, if these are
incompatible with your compiler, your should temporarily define
a macro named @code{__attributes__} to remove all attributes.

Because of libkeccak's simplicity it does not have a pkg-config
file. Instead, you only need to specify the flag @code{-lkeccak}
when linking your binaries. No flags are required during compilation
(of object files.)

To make libkeccak's API available, include the header file
@file{<libkeccak.h>} in your source files.



@node GNU Affero General Public License
@appendix GNU Affero General Public License
@include agpl-3.0.texinfo

@node GNU Free Documentation License
@appendix GNU Free Documentation License
@include fdl-1.3.texinfo

@node Concept index
@unnumbered Concept index
@printindex cp

@node Data type index
@unnumbered Data type index
@printindex tp

@node Function index
@unnumbered Function index
@printindex fn


@bye