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Commit 44821d57 authored by Karl Berry's avatar Karl Berry Committed by Niels Möller
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Fixes from Karl Berry. Changed license to GNU 

FDL, with no invariant sections. Added some more index terms.

Rev: nettle/nettle.texinfo:1.4
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nettle/nettle.texinfo
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\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename nettle.info
@settitle The Nettle low-level cryptographic library.
@c %**end of header
@settitle Nettle: a low-level cryptographic library
@documentencoding ISO-8859-1
@footnotestyle end
@syncodeindex fn cp
@c %**end of header
@dircategory GNU Libraries
@direntry
* Nettle: (nettle). A low-level cryptographics library.
@end direntry
@set COPYRIGHT-YEARS 2001, 2004, 2005
@set UPDATED-FOR 2.0
@c Latin-1 doesn't work with TeX output.
@c Also lookout for é characters.
@iftex
@set AUTHOR Niels M@"oller
@end iftex
@ifnottex
@set UPDATED-FOR 1.15
@set AUTHOR Niels Möller
@end ifnottex
@ifinfo
Manual for the Nettle library. This manual corresponds to version
@value{UPDATED-FOR}.
@copying
This manual is for the Nettle library (version @value{UPDATED-FOR}), a
low-level cryptographic library.
Copyright @value{COPYRIGHT-YEARS} @value{AUTHOR}
Copyright 2001, 2004, 2005, 2009 @value{AUTHOR}.
Permission is granted to make and distribute verbatim
copies of this manual provided the copyright notice and
this permission notice are preserved on all copies.
@ignore
Permission is granted to process this file through TeX
and print the results, provided the printed document
carries a copying permission notice identical to this
one except for the removal of this paragraph (this
paragraph not being relevant to the printed manual).
@end ignore
Permission is granted to copy and distribute modified
versions of this manual under the conditions for
verbatim copying, provided also that the sections
entitled ``Copying'' and ``GNU General Public License''
are included exactly as in the original, and provided
that the entire resulting derived work is distributed
under the terms of a permission notice identical to this
one.
Permission is granted to copy and distribute
translations of this manual into another language,
under the above conditions for modified versions,
except that this permission notice may be stated in a
translation approved by the Free Software Foundation.
@end ifinfo
@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
Texts. A copy of the license is included in
@ref{GNU Free Documentation License}.
@end quotation
@end copying
@titlepage
@sp 10
@c @center @titlefont{Nettle Manual}
@title Nettle Manual
@subtitle For the Nettle Library version @value{UPDATED-FOR}
@author @value{AUTHOR}
@c The following two commands start the copyright page.
@page
@vskip 0pt plus 1filll
Copyright @copyright{} @value{COPYRIGHT-YEARS} @value{AUTHOR}
Permission is granted to make and distribute verbatim
copies of this manual provided the copyright notice and
this permission notice are preserved on all copies.
Permission is granted to copy and distribute modified
versions of this manual under the conditions for
verbatim copying, provided also that the sections
entitled ``Copying'' and ``GNU General Public License''
are included exactly as in the original, and provided
that the entire resulting derived work is distributed
under the terms of a permission notice identical to this
one.
Permission is granted to copy and distribute
translations of this manual into another language,
under the above conditions for modified versions,
except that this permission notice may be stated in a
translation approved by the Free Software Foundation.
@insertcopying
@end titlepage
@dircategory Encryption
@direntry
* Nettle: (nettle). A low-level cryptographic library.
@end direntry
@contents
@ifnottex
......@@ -105,12 +47,11 @@ translation approved by the Free Software Foundation.
@comment node-name, next, previous, up
@top Nettle
This document describes the nettle low-level cryptographic library. You
can use the library directly from your C programs, or (recommended)
write or use an object-oriented wrapper for your favorite language or
application.
This document describes the Nettle low-level cryptographic library. You
can use the library directly from your C programs, or write or use an
object-oriented wrapper for your favorite language or application.
This manual corresponds to version @value{UPDATED-FOR} of the library.
@insertcopying
@menu
* Introduction:: What is Nettle?
......@@ -121,6 +62,7 @@ This manual corresponds to version @value{UPDATED-FOR} of the library.
* Reference:: All Nettle functions and features.
* Nettle soup:: For the serious nettle hacker.
* Installation:: How to install Nettle.
* GNU Free Documentation License::
* Index:: Function and concept index.
@end menu
......@@ -336,7 +278,7 @@ This chapter describes all the Nettle functions, grouped by family.
@node Hash functions, Cipher functions, Reference, Reference
@comment node-name, next, previous, up
@section Hash functions
@cindex Hash function
A cryptographic @dfn{hash function} is a function that takes variable
size strings, and maps them to strings of fixed, short, length. There
are naturally lots of collisions, as there are more possible 1MB files
......@@ -347,10 +289,12 @@ to find the collisions. More precisely, a cryptographic hash function
@table @emph
@item One-way
@cindex One-way
Given a hash value @code{H(x)} it is hard to find a string @code{x}
that hashes to that value.
@item Collision-resistant
@cindex Collision-resistant
It is hard to find two different strings, @code{x} and @code{y}, such
that @code{H(x)} = @code{H(y)}.
......@@ -587,6 +531,7 @@ These are all the hash functions that Nettle implements.
@node Cipher functions, Cipher modes, Hash functions, Reference
@comment node-name, next, previous, up
@section Cipher functions
@cindex Cipher
A @dfn{cipher} is a function that takes a message or @dfn{plaintext}
and a secret @dfn{key} and transforms it to a @dfn{ciphertext}. Given
......@@ -594,6 +539,9 @@ only the ciphertext, but not the key, it should be hard to find the
plaintext. Given matching pairs of plaintext and ciphertext, it should
be hard to find the key.
@cindex Block Cipher
@cindex Stream Cipher
There are two main classes of ciphers: Block ciphers and stream ciphers.
A block cipher can process data only in fixed size chunks, called
......@@ -1163,6 +1111,9 @@ secure.
@subsection Cipher Block Chaining
@cindex Cipher Block Chaining
@cindex CBC Mode
When using @acronym{CBC} mode, plaintext blocks are not encrypted
independently of each other, like in Electronic Cook Book mode. Instead,
when encrypting a block in @acronym{CBC} mode, the previous ciphertext
......@@ -1251,10 +1202,13 @@ an @code{struct aes_ctx} context with the @code{des_encrypt} function.
@subsection Counter mode
Counter mode uses the block cipher as a keyed pseudo-random generator.
The output of the generator is XORed with the data to be encrypted. It
can be understood as a way to transform a block cipher to a stream
cipher.
@cindex Counter Mode
@cindex CTR Mode
Counter mode (@acronym{CTR}) uses the block cipher as a keyed
pseudo-random generator. The output of the generator is XORed with the
data to be encrypted. It can be understood as a way to transform a block
cipher to a stream cipher.
The message is divided into @code{n} blocks @code{M_1},@dots{}
@code{M_n}, where @code{M_n} is of size @code{m} which may be smaller
......@@ -1325,6 +1279,10 @@ operation.
@comment node-name, next, previous, up
@section Keyed Hash Functions
@cindex Keyed Hash Function
@cindex Message Authentication Code
@cindex MAC
A @dfn{keyed hash function}, or @dfn{Message Authentication Code}
(@acronym{MAC}) is a function that takes a key and a message, and
produces fixed size @acronym{MAC}. It should be hard to compute a
......@@ -1540,6 +1498,9 @@ secure way. And if there are many users or entities that need to
communicate, each @emph{pair} needs a shared secret key known by nobody
else.
@cindex Public Key Cryptography
@cindex One-way function
Public-key cryptography uses trapdoor one-way functions. A
@dfn{one-way function} is a function @code{F} such that it is easy to
compute the value @code{F(x)} for any @code{x}, but given a value
......@@ -1999,6 +1960,8 @@ Returns 1 on success, and 0 on failure. The function will fail if
@comment node-name, next, previous, up
@section Randomness
@cindex Randomness
A crucial ingredient in many cryptographic contexts is randomness: Let
@code{p} be a random prime, choose a random initialization vector
@code{iv}, a random key @code{k} and a random exponent @code{e}, etc. In
......@@ -2048,6 +2011,9 @@ other information he knows about the seeding process, still can't guess
the seed correctly, then the conditional entropy is more than @code{n}
bits.
@cindex Entropy
@cindex Conditional entropy
Let's look at an example. Say information about timing of received
network packets is used in the seeding process. If there is some random
network traffic going on, this will contribute some bits of entropy or
......@@ -2409,7 +2375,7 @@ smaks
Servera med kokta ägghalvor.
@end ignore
@node Installation, Index, Nettle soup, Top
@node Installation, GNU Free Documentation License, Nettle soup, Top
@comment node-name, next, previous, up
@chapter Installation
......@@ -2438,7 +2404,12 @@ Using GNU make is recommended. For other make programs, in particular
BSD make, you may have to use the @option{--disable-dependency-tracking}
option to @command{./configure}.
@node Index, , Installation, Top
@node GNU Free Documentation License, Index, Installation, Top
@appendix GNU Free Documentation License
@cindex Free Documentation License
@include fdl.texi
@node Index, , GNU Free Documentation License, Top
@comment node-name, next, previous, up
@unnumbered Function and Concept Index
......
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