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+<?xml version="1.0" encoding="UTF-8"?>
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+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
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+ "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
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+
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+<book id="KernelCryptoAPI">
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+ <bookinfo>
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+ <title>Linux Kernel Crypto API</title>
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+
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+ <authorgroup>
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+ <author>
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+ <firstname>Stephan</firstname>
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+ <surname>Mueller</surname>
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+ <affiliation>
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+ <address>
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+ <email>smueller@chronox.de</email>
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+ </address>
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+ </affiliation>
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+ </author>
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+ <author>
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+ <firstname>Marek</firstname>
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+ <surname>Vasut</surname>
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+ <affiliation>
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+ <address>
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+ <email>marek@denx.de</email>
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+ </address>
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+ </affiliation>
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+ </author>
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+ </authorgroup>
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+
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+ <copyright>
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+ <year>2014</year>
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+ <holder>Stephan Mueller</holder>
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+ </copyright>
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+
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+
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+ <legalnotice>
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+ <para>
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+ This documentation is free software; you can redistribute
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+ it and/or modify it under the terms of the GNU General Public
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+ License as published by the Free Software Foundation; either
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+ version 2 of the License, or (at your option) any later
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+ version.
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+ </para>
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+
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+ <para>
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+ This program is distributed in the hope that it will be
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+ useful, but WITHOUT ANY WARRANTY; without even the implied
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+ warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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+ See the GNU General Public License for more details.
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+ </para>
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+
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+ <para>
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+ You should have received a copy of the GNU General Public
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+ License along with this program; if not, write to the Free
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+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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+ MA 02111-1307 USA
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+ </para>
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+
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+ <para>
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+ For more details see the file COPYING in the source
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+ distribution of Linux.
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+ </para>
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+ </legalnotice>
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+ </bookinfo>
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+
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+ <toc></toc>
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+
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+ <chapter id="Intro">
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+ <title>Kernel Crypto API Interface Specification</title>
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+
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+ <sect1><title>Introduction</title>
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+
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+ <para>
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+ The kernel crypto API offers a rich set of cryptographic ciphers as
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+ well as other data transformation mechanisms and methods to invoke
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+ these. This document contains a description of the API and provides
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+ example code.
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+ </para>
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+
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+ <para>
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+ To understand and properly use the kernel crypto API a brief
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+ explanation of its structure is given. Based on the architecture,
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+ the API can be separated into different components. Following the
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+ architecture specification, hints to developers of ciphers are
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+ provided. Pointers to the API function call documentation are
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+ given at the end.
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+ </para>
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+
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+ <para>
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+ The kernel crypto API refers to all algorithms as "transformations".
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+ Therefore, a cipher handle variable usually has the name "tfm".
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+ Besides cryptographic operations, the kernel crypto API also knows
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+ compression transformations and handles them the same way as ciphers.
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+ </para>
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+
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+ <para>
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+ The kernel crypto API serves the following entity types:
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+
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+ <itemizedlist>
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+ <listitem>
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+ <para>consumers requesting cryptographic services</para>
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+ </listitem>
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+ <listitem>
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+ <para>data transformation implementations (typically ciphers)
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+ that can be called by consumers using the kernel crypto
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+ API</para>
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+ </listitem>
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+ </itemizedlist>
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+ </para>
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+
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+ <para>
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+ This specification is intended for consumers of the kernel crypto
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+ API as well as for developers implementing ciphers. This API
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+ specification, however, does not discusses all API calls available
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+ to data transformation implementations (i.e. implementations of
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+ ciphers and other transformations (such as CRC or even compression
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+ algorithms) that can register with the kernel crypto API).
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+ </para>
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+
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+ <para>
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+ Note: The terms "transformation" and cipher algorithm are used
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+ interchangably.
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+ </para>
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+ </sect1>
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+
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+ <sect1><title>Terminology</title>
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+ <para>
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+ The transformation implementation is an actual code or interface
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+ to hardware which implements a certain transformation with precisely
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+ defined behavior.
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+ </para>
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+
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+ <para>
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+ The transformation object (TFM) is an instance of a transformation
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+ implementation. There can be multiple transformation objects
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+ associated with a single transformation implementation. Each of
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+ those transformation objects is held by a crypto API consumer or
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+ another transformation. Transformation object is allocated when a
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+ crypto API consumer requests a transformation implementation.
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+ The consumer is then provided with a structure, which contains
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+ a transformation object (TFM).
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+ </para>
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+
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+ <para>
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+ The structure that contains transformation objects may also be
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+ referred to as a "cipher handle". Such a cipher handle is always
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+ subject to the following phases that are reflected in the API calls
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+ applicable to such a cipher handle:
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+ </para>
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+
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+ <orderedlist>
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+ <listitem>
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+ <para>Initialization of a cipher handle.</para>
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+ </listitem>
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+ <listitem>
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+ <para>Execution of all intended cipher operations applicable
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+ for the handle where the cipher handle must be furnished to
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+ every API call.</para>
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+ </listitem>
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+ <listitem>
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+ <para>Destruction of a cipher handle.</para>
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+ </listitem>
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+ </orderedlist>
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+
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+ <para>
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+ When using the initialization API calls, a cipher handle is
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+ created and returned to the consumer. Therefore, please refer
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+ to all initialization API calls that refer to the data
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+ structure type a consumer is expected to receive and subsequently
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+ to use. The initialization API calls have all the same naming
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+ conventions of crypto_alloc_*.
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+ </para>
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+
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+ <para>
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+ The transformation context is private data associated with
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+ the transformation object.
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+ </para>
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+ </sect1>
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+ </chapter>
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+
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+ <chapter id="Architecture"><title>Kernel Crypto API Architecture</title>
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+ <sect1><title>Cipher algorithm types</title>
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+ <para>
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+ The kernel crypto API provides different API calls for the
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+ following cipher types:
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+
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+ <itemizedlist>
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+ <listitem><para>Symmetric ciphers</para></listitem>
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+ <listitem><para>AEAD ciphers</para></listitem>
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+ <listitem><para>Message digest, including keyed message digest</para></listitem>
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+ <listitem><para>Random number generation</para></listitem>
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+ <listitem><para>User space interface</para></listitem>
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+ </itemizedlist>
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+ </para>
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+ </sect1>
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+
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+ <sect1><title>Ciphers And Templates</title>
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+ <para>
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+ The kernel crypto API provides implementations of single block
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+ ciphers and message digests. In addition, the kernel crypto API
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+ provides numerous "templates" that can be used in conjunction
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+ with the single block ciphers and message digests. Templates
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+ include all types of block chaining mode, the HMAC mechanism, etc.
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+ </para>
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+
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+ <para>
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+ Single block ciphers and message digests can either be directly
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+ used by a caller or invoked together with a template to form
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+ multi-block ciphers or keyed message digests.
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+ </para>
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+
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+ <para>
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+ A single block cipher may even be called with multiple templates.
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+ However, templates cannot be used without a single cipher.
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+ </para>
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+
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+ <para>
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+ See /proc/crypto and search for "name". For example:
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+
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+ <itemizedlist>
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+ <listitem><para>aes</para></listitem>
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+ <listitem><para>ecb(aes)</para></listitem>
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+ <listitem><para>cmac(aes)</para></listitem>
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+ <listitem><para>ccm(aes)</para></listitem>
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+ <listitem><para>rfc4106(gcm(aes))</para></listitem>
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+ <listitem><para>sha1</para></listitem>
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+ <listitem><para>hmac(sha1)</para></listitem>
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+ <listitem><para>authenc(hmac(sha1),cbc(aes))</para></listitem>
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+ </itemizedlist>
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+ </para>
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+
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+ <para>
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+ In these examples, "aes" and "sha1" are the ciphers and all
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+ others are the templates.
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+ </para>
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+ </sect1>
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+
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+ <sect1><title>Synchronous And Asynchronous Operation</title>
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+ <para>
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+ The kernel crypto API provides synchronous and asynchronous
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+ API operations.
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+ </para>
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+
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+ <para>
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+ When using the synchronous API operation, the caller invokes
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+ a cipher operation which is performed synchronously by the
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+ kernel crypto API. That means, the caller waits until the
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+ cipher operation completes. Therefore, the kernel crypto API
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+ calls work like regular function calls. For synchronous
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+ operation, the set of API calls is small and conceptually
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+ similar to any other crypto library.
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+ </para>
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+
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+ <para>
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+ Asynchronous operation is provided by the kernel crypto API
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+ which implies that the invocation of a cipher operation will
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+ complete almost instantly. That invocation triggers the
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+ cipher operation but it does not signal its completion. Before
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+ invoking a cipher operation, the caller must provide a callback
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+ function the kernel crypto API can invoke to signal the
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+ completion of the cipher operation. Furthermore, the caller
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+ must ensure it can handle such asynchronous events by applying
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+ appropriate locking around its data. The kernel crypto API
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+ does not perform any special serialization operation to protect
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+ the caller's data integrity.
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+ </para>
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+ </sect1>
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+
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+ <sect1><title>Crypto API Cipher References And Priority</title>
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+ <para>
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+ A cipher is referenced by the caller with a string. That string
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+ has the following semantics:
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+
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+ <programlisting>
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+ template(single block cipher)
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+ </programlisting>
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+
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+ where "template" and "single block cipher" is the aforementioned
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+ template and single block cipher, respectively. If applicable,
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+ additional templates may enclose other templates, such as
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+
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+ <programlisting>
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+ template1(template2(single block cipher)))
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+ </programlisting>
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+ </para>
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+
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+ <para>
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+ The kernel crypto API may provide multiple implementations of a
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+ template or a single block cipher. For example, AES on newer
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+ Intel hardware has the following implementations: AES-NI,
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+ assembler implementation, or straight C. Now, when using the
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+ string "aes" with the kernel crypto API, which cipher
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+ implementation is used? The answer to that question is the
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+ priority number assigned to each cipher implementation by the
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+ kernel crypto API. When a caller uses the string to refer to a
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+ cipher during initialization of a cipher handle, the kernel
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+ crypto API looks up all implementations providing an
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+ implementation with that name and selects the implementation
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+ with the highest priority.
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+ </para>
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+
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+ <para>
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+ Now, a caller may have the need to refer to a specific cipher
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+ implementation and thus does not want to rely on the
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+ priority-based selection. To accommodate this scenario, the
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+ kernel crypto API allows the cipher implementation to register
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+ a unique name in addition to common names. When using that
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+ unique name, a caller is therefore always sure to refer to
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+ the intended cipher implementation.
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+ </para>
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+
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+ <para>
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+ The list of available ciphers is given in /proc/crypto. However,
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+ that list does not specify all possible permutations of
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+ templates and ciphers. Each block listed in /proc/crypto may
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+ contain the following information -- if one of the components
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+ listed as follows are not applicable to a cipher, it is not
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+ displayed:
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+ </para>
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+
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+ <itemizedlist>
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+ <listitem>
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+ <para>name: the generic name of the cipher that is subject
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+ to the priority-based selection -- this name can be used by
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+ the cipher allocation API calls (all names listed above are
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+ examples for such generic names)</para>
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+ </listitem>
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+ <listitem>
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+ <para>driver: the unique name of the cipher -- this name can
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+ be used by the cipher allocation API calls</para>
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+ </listitem>
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+ <listitem>
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+ <para>module: the kernel module providing the cipher
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+ implementation (or "kernel" for statically linked ciphers)</para>
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+ </listitem>
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+ <listitem>
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+ <para>priority: the priority value of the cipher implementation</para>
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+ </listitem>
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+ <listitem>
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+ <para>refcnt: the reference count of the respective cipher
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+ (i.e. the number of current consumers of this cipher)</para>
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+ </listitem>
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+ <listitem>
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+ <para>selftest: specification whether the self test for the
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+ cipher passed</para>
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+ </listitem>
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+ <listitem>
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+ <para>type:
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+ <itemizedlist>
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+ <listitem>
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+ <para>blkcipher for synchronous block ciphers</para>
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+ </listitem>
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+ <listitem>
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+ <para>ablkcipher for asynchronous block ciphers</para>
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+ </listitem>
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+ <listitem>
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+ <para>cipher for single block ciphers that may be used with
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+ an additional template</para>
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+ </listitem>
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+ <listitem>
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+ <para>shash for synchronous message digest</para>
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+ </listitem>
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+ <listitem>
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+ <para>ahash for asynchronous message digest</para>
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+ </listitem>
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+ <listitem>
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+ <para>aead for AEAD cipher type</para>
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+ </listitem>
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+ <listitem>
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+ <para>compression for compression type transformations</para>
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+ </listitem>
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+ <listitem>
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+ <para>rng for random number generator</para>
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+ </listitem>
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+ <listitem>
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+ <para>givcipher for cipher with associated IV generator
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+ (see the geniv entry below for the specification of the
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+ IV generator type used by the cipher implementation)</para>
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+ </listitem>
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+ </itemizedlist>
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+ </para>
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+ </listitem>
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+ <listitem>
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+ <para>blocksize: blocksize of cipher in bytes</para>
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+ </listitem>
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+ <listitem>
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+ <para>keysize: key size in bytes</para>
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+ </listitem>
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+ <listitem>
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+ <para>ivsize: IV size in bytes</para>
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+ </listitem>
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+ <listitem>
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+ <para>seedsize: required size of seed data for random number
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+ generator</para>
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+ </listitem>
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+ <listitem>
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+ <para>digestsize: output size of the message digest</para>
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+ </listitem>
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+ <listitem>
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+ <para>geniv: IV generation type:
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+ <itemizedlist>
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+ <listitem>
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+ <para>eseqiv for encrypted sequence number based IV
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+ generation</para>
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+ </listitem>
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+ <listitem>
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+ <para>seqiv for sequence number based IV generation</para>
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+ </listitem>
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+ <listitem>
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+ <para>chainiv for chain iv generation</para>
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+ </listitem>
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+ <listitem>
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+ <para><builtin> is a marker that the cipher implements
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+ IV generation and handling as it is specific to the given
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+ cipher</para>
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+ </listitem>
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+ </itemizedlist>
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+ </para>
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+ </listitem>
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+ </itemizedlist>
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+ </sect1>
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+
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+ <sect1><title>Key Sizes</title>
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+ <para>
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+ When allocating a cipher handle, the caller only specifies the
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+ cipher type. Symmetric ciphers, however, typically support
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|
+ multiple key sizes (e.g. AES-128 vs. AES-192 vs. AES-256).
|
|
|
+ These key sizes are determined with the length of the provided
|
|
|
+ key. Thus, the kernel crypto API does not provide a separate
|
|
|
+ way to select the particular symmetric cipher key size.
|
|
|
+ </para>
|
|
|
+ </sect1>
|
|
|
+
|
|
|
+ <sect1><title>Cipher Allocation Type And Masks</title>
|
|
|
+ <para>
|
|
|
+ The different cipher handle allocation functions allow the
|
|
|
+ specification of a type and mask flag. Both parameters have
|
|
|
+ the following meaning (and are therefore not covered in the
|
|
|
+ subsequent sections).
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ The type flag specifies the type of the cipher algorithm.
|
|
|
+ The caller usually provides a 0 when the caller wants the
|
|
|
+ default handling. Otherwise, the caller may provide the
|
|
|
+ following selections which match the the aforementioned
|
|
|
+ cipher types:
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <itemizedlist>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_CIPHER Single block cipher</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_COMPRESS Compression</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_AEAD Authenticated Encryption with
|
|
|
+ Associated Data (MAC)</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_BLKCIPHER Synchronous multi-block cipher</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_ABLKCIPHER Asynchronous multi-block cipher</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_GIVCIPHER Asynchronous multi-block
|
|
|
+ cipher packed together with an IV generator (see geniv field
|
|
|
+ in the /proc/crypto listing for the known IV generators)</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_DIGEST Raw message digest</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_HASH Alias for CRYPTO_ALG_TYPE_DIGEST</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_SHASH Synchronous multi-block hash</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_AHASH Asynchronous multi-block hash</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_RNG Random Number Generation</para>
|
|
|
+ </listitem>
|
|
|
+ <listitem>
|
|
|
+ <para>CRYPTO_ALG_TYPE_PCOMPRESS Enhanced version of
|
|
|
+ CRYPTO_ALG_TYPE_COMPRESS allowing for segmented compression /
|
|
|
+ decompression instead of performing the operation on one
|
|
|
+ segment only. CRYPTO_ALG_TYPE_PCOMPRESS is intended to replace
|
|
|
+ CRYPTO_ALG_TYPE_COMPRESS once existing consumers are converted.</para>
|
|
|
+ </listitem>
|
|
|
+ </itemizedlist>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ The mask flag restricts the type of cipher. The only allowed
|
|
|
+ flag is CRYPTO_ALG_ASYNC to restrict the cipher lookup function
|
|
|
+ to asynchronous ciphers. Usually, a caller provides a 0 for the
|
|
|
+ mask flag.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ When the caller provides a mask and type specification, the
|
|
|
+ caller limits the search the kernel crypto API can perform for
|
|
|
+ a suitable cipher implementation for the given cipher name.
|
|
|
+ That means, even when a caller uses a cipher name that exists
|
|
|
+ during its initialization call, the kernel crypto API may not
|
|
|
+ select it due to the used type and mask field.
|
|
|
+ </para>
|
|
|
+ </sect1>
|
|
|
+ </chapter>
|
|
|
+
|
|
|
+ <chapter id="Development"><title>Developing Cipher Algorithms</title>
|
|
|
+ <sect1><title>Registering And Unregistering Transformation</title>
|
|
|
+ <para>
|
|
|
+ There are three distinct types of registration functions in
|
|
|
+ the Crypto API. One is used to register a generic cryptographic
|
|
|
+ transformation, while the other two are specific to HASH
|
|
|
+ transformations and COMPRESSion. We will discuss the latter
|
|
|
+ two in a separate chapter, here we will only look at the
|
|
|
+ generic ones.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Before discussing the register functions, the data structure
|
|
|
+ to be filled with each, struct crypto_alg, must be considered
|
|
|
+ -- see below for a description of this data structure.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ The generic registration functions can be found in
|
|
|
+ include/linux/crypto.h and their definition can be seen below.
|
|
|
+ The former function registers a single transformation, while
|
|
|
+ the latter works on an array of transformation descriptions.
|
|
|
+ The latter is useful when registering transformations in bulk.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <programlisting>
|
|
|
+ int crypto_register_alg(struct crypto_alg *alg);
|
|
|
+ int crypto_register_algs(struct crypto_alg *algs, int count);
|
|
|
+ </programlisting>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ The counterparts to those functions are listed below.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <programlisting>
|
|
|
+ int crypto_unregister_alg(struct crypto_alg *alg);
|
|
|
+ int crypto_unregister_algs(struct crypto_alg *algs, int count);
|
|
|
+ </programlisting>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Notice that both registration and unregistration functions
|
|
|
+ do return a value, so make sure to handle errors. A return
|
|
|
+ code of zero implies success. Any return code < 0 implies
|
|
|
+ an error.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ The bulk registration / unregistration functions require
|
|
|
+ that struct crypto_alg is an array of count size. These
|
|
|
+ functions simply loop over that array and register /
|
|
|
+ unregister each individual algorithm. If an error occurs,
|
|
|
+ the loop is terminated at the offending algorithm definition.
|
|
|
+ That means, the algorithms prior to the offending algorithm
|
|
|
+ are successfully registered. Note, the caller has no way of
|
|
|
+ knowing which cipher implementations have successfully
|
|
|
+ registered. If this is important to know, the caller should
|
|
|
+ loop through the different implementations using the single
|
|
|
+ instance *_alg functions for each individual implementation.
|
|
|
+ </para>
|
|
|
+ </sect1>
|
|
|
+
|
|
|
+ <sect1><title>Single-Block Symmetric Ciphers [CIPHER]</title>
|
|
|
+ <para>
|
|
|
+ Example of transformations: aes, arc4, ...
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ This section describes the simplest of all transformation
|
|
|
+ implementations, that being the CIPHER type used for symmetric
|
|
|
+ ciphers. The CIPHER type is used for transformations which
|
|
|
+ operate on exactly one block at a time and there are no
|
|
|
+ dependencies between blocks at all.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <sect2><title>Registration specifics</title>
|
|
|
+ <para>
|
|
|
+ The registration of [CIPHER] algorithm is specific in that
|
|
|
+ struct crypto_alg field .cra_type is empty. The .cra_u.cipher
|
|
|
+ has to be filled in with proper callbacks to implement this
|
|
|
+ transformation.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ See struct cipher_alg below.
|
|
|
+ </para>
|
|
|
+ </sect2>
|
|
|
+
|
|
|
+ <sect2><title>Cipher Definition With struct cipher_alg</title>
|
|
|
+ <para>
|
|
|
+ Struct cipher_alg defines a single block cipher.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Here are schematics of how these functions are called when
|
|
|
+ operated from other part of the kernel. Note that the
|
|
|
+ .cia_setkey() call might happen before or after any of these
|
|
|
+ schematics happen, but must not happen during any of these
|
|
|
+ are in-flight.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ <programlisting>
|
|
|
+ KEY ---. PLAINTEXT ---.
|
|
|
+ v v
|
|
|
+ .cia_setkey() -> .cia_encrypt()
|
|
|
+ |
|
|
|
+ '-----> CIPHERTEXT
|
|
|
+ </programlisting>
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Please note that a pattern where .cia_setkey() is called
|
|
|
+ multiple times is also valid:
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ <programlisting>
|
|
|
+
|
|
|
+ KEY1 --. PLAINTEXT1 --. KEY2 --. PLAINTEXT2 --.
|
|
|
+ v v v v
|
|
|
+ .cia_setkey() -> .cia_encrypt() -> .cia_setkey() -> .cia_encrypt()
|
|
|
+ | |
|
|
|
+ '---> CIPHERTEXT1 '---> CIPHERTEXT2
|
|
|
+ </programlisting>
|
|
|
+ </para>
|
|
|
+
|
|
|
+ </sect2>
|
|
|
+ </sect1>
|
|
|
+
|
|
|
+ <sect1><title>Multi-Block Ciphers [BLKCIPHER] [ABLKCIPHER]</title>
|
|
|
+ <para>
|
|
|
+ Example of transformations: cbc(aes), ecb(arc4), ...
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ This section describes the multi-block cipher transformation
|
|
|
+ implementations for both synchronous [BLKCIPHER] and
|
|
|
+ asynchronous [ABLKCIPHER] case. The multi-block ciphers are
|
|
|
+ used for transformations which operate on scatterlists of
|
|
|
+ data supplied to the transformation functions. They output
|
|
|
+ the result into a scatterlist of data as well.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <sect2><title>Registration Specifics</title>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ The registration of [BLKCIPHER] or [ABLKCIPHER] algorithms
|
|
|
+ is one of the most standard procedures throughout the crypto API.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Note, if a cipher implementation requires a proper alignment
|
|
|
+ of data, the caller should use the functions of
|
|
|
+ crypto_blkcipher_alignmask() or crypto_ablkcipher_alignmask()
|
|
|
+ respectively to identify a memory alignment mask. The kernel
|
|
|
+ crypto API is able to process requests that are unaligned.
|
|
|
+ This implies, however, additional overhead as the kernel
|
|
|
+ crypto API needs to perform the realignment of the data which
|
|
|
+ may imply moving of data.
|
|
|
+ </para>
|
|
|
+ </sect2>
|
|
|
+
|
|
|
+ <sect2><title>Cipher Definition With struct blkcipher_alg and ablkcipher_alg</title>
|
|
|
+ <para>
|
|
|
+ Struct blkcipher_alg defines a synchronous block cipher whereas
|
|
|
+ struct ablkcipher_alg defines an asynchronous block cipher.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Please refer to the single block cipher description for schematics
|
|
|
+ of the block cipher usage. The usage patterns are exactly the same
|
|
|
+ for [ABLKCIPHER] and [BLKCIPHER] as they are for plain [CIPHER].
|
|
|
+ </para>
|
|
|
+ </sect2>
|
|
|
+
|
|
|
+ <sect2><title>Specifics Of Asynchronous Multi-Block Cipher</title>
|
|
|
+ <para>
|
|
|
+ There are a couple of specifics to the [ABLKCIPHER] interface.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ First of all, some of the drivers will want to use the
|
|
|
+ Generic ScatterWalk in case the hardware needs to be fed
|
|
|
+ separate chunks of the scatterlist which contains the
|
|
|
+ plaintext and will contain the ciphertext. Please refer
|
|
|
+ to the ScatterWalk interface offered by the Linux kernel
|
|
|
+ scatter / gather list implementation.
|
|
|
+ </para>
|
|
|
+ </sect2>
|
|
|
+ </sect1>
|
|
|
+
|
|
|
+ <sect1><title>Hashing [HASH]</title>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Example of transformations: crc32, md5, sha1, sha256,...
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <sect2><title>Registering And Unregistering The Transformation</title>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ There are multiple ways to register a HASH transformation,
|
|
|
+ depending on whether the transformation is synchronous [SHASH]
|
|
|
+ or asynchronous [AHASH] and the amount of HASH transformations
|
|
|
+ we are registering. You can find the prototypes defined in
|
|
|
+ include/crypto/internal/hash.h:
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <programlisting>
|
|
|
+ int crypto_register_ahash(struct ahash_alg *alg);
|
|
|
+
|
|
|
+ int crypto_register_shash(struct shash_alg *alg);
|
|
|
+ int crypto_register_shashes(struct shash_alg *algs, int count);
|
|
|
+ </programlisting>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ The respective counterparts for unregistering the HASH
|
|
|
+ transformation are as follows:
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <programlisting>
|
|
|
+ int crypto_unregister_ahash(struct ahash_alg *alg);
|
|
|
+
|
|
|
+ int crypto_unregister_shash(struct shash_alg *alg);
|
|
|
+ int crypto_unregister_shashes(struct shash_alg *algs, int count);
|
|
|
+ </programlisting>
|
|
|
+ </sect2>
|
|
|
+
|
|
|
+ <sect2><title>Cipher Definition With struct shash_alg and ahash_alg</title>
|
|
|
+ <para>
|
|
|
+ Here are schematics of how these functions are called when
|
|
|
+ operated from other part of the kernel. Note that the .setkey()
|
|
|
+ call might happen before or after any of these schematics happen,
|
|
|
+ but must not happen during any of these are in-flight. Please note
|
|
|
+ that calling .init() followed immediately by .finish() is also a
|
|
|
+ perfectly valid transformation.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <programlisting>
|
|
|
+ I) DATA -----------.
|
|
|
+ v
|
|
|
+ .init() -> .update() -> .final() ! .update() might not be called
|
|
|
+ ^ | | at all in this scenario.
|
|
|
+ '----' '---> HASH
|
|
|
+
|
|
|
+ II) DATA -----------.-----------.
|
|
|
+ v v
|
|
|
+ .init() -> .update() -> .finup() ! .update() may not be called
|
|
|
+ ^ | | at all in this scenario.
|
|
|
+ '----' '---> HASH
|
|
|
+
|
|
|
+ III) DATA -----------.
|
|
|
+ v
|
|
|
+ .digest() ! The entire process is handled
|
|
|
+ | by the .digest() call.
|
|
|
+ '---------------> HASH
|
|
|
+ </programlisting>
|
|
|
+
|
|
|
+ <para>
|
|
|
+ Here is a schematic of how the .export()/.import() functions are
|
|
|
+ called when used from another part of the kernel.
|
|
|
+ </para>
|
|
|
+
|
|
|
+ <programlisting>
|
|
|
+ KEY--. DATA--.
|
|
|
+ v v ! .update() may not be called
|
|
|
+ .setkey() -> .init() -> .update() -> .export() at all in this scenario.
|
|
|
+ ^ | |
|
|
|
+ '-----' '--> PARTIAL_HASH
|
|
|
+
|
|
|
+ ----------- other transformations happen here -----------
|
|
|
+
|
|
|
+ PARTIAL_HASH--. DATA1--.
|
|
|
+ v v
|
|
|
+ .import -> .update() -> .final() ! .update() may not be called
|
|
|
+ ^ | | at all in this scenario.
|
|
|
+ '----' '--> HASH1
|
|
|
+
|
|
|
+ PARTIAL_HASH--. DATA2-.
|
|
|
+ v v
|
|
|
+ .import -> .finup()
|
|
|
+ |
|
|
|
+ '---------------> HASH2
|
|
|
+ </programlisting>
|
|
|
+ </sect2>
|
|
|
+
|
|
|
+ <sect2><title>Specifics Of Asynchronous HASH Transformation</title>
|
|
|
+ <para>
|
|
|
+ Some of the drivers will want to use the Generic ScatterWalk
|
|
|
+ in case the implementation needs to be fed separate chunks of the
|
|
|
+ scatterlist which contains the input data. The buffer containing
|
|
|
+ the resulting hash will always be properly aligned to
|
|
|
+ .cra_alignmask so there is no need to worry about this.
|
|
|
+ </para>
|
|
|
+ </sect2>
|
|
|
+ </sect1>
|
|
|
+ </chapter>
|
|
|
+
|
|
|
+ <chapter id="API"><title>Programming Interface</title>
|
|
|
+ <sect1><title>Block Cipher Context Data Structures</title>
|
|
|
+!Pinclude/linux/crypto.h Block Cipher Context Data Structures
|
|
|
+!Finclude/linux/crypto.h aead_request
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Block Cipher Algorithm Definitions</title>
|
|
|
+!Pinclude/linux/crypto.h Block Cipher Algorithm Definitions
|
|
|
+!Finclude/linux/crypto.h crypto_alg
|
|
|
+!Finclude/linux/crypto.h ablkcipher_alg
|
|
|
+!Finclude/linux/crypto.h aead_alg
|
|
|
+!Finclude/linux/crypto.h blkcipher_alg
|
|
|
+!Finclude/linux/crypto.h cipher_alg
|
|
|
+!Finclude/linux/crypto.h rng_alg
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Asynchronous Block Cipher API</title>
|
|
|
+!Pinclude/linux/crypto.h Asynchronous Block Cipher API
|
|
|
+!Finclude/linux/crypto.h crypto_alloc_ablkcipher
|
|
|
+!Finclude/linux/crypto.h crypto_free_ablkcipher
|
|
|
+!Finclude/linux/crypto.h crypto_has_ablkcipher
|
|
|
+!Finclude/linux/crypto.h crypto_ablkcipher_ivsize
|
|
|
+!Finclude/linux/crypto.h crypto_ablkcipher_blocksize
|
|
|
+!Finclude/linux/crypto.h crypto_ablkcipher_setkey
|
|
|
+!Finclude/linux/crypto.h crypto_ablkcipher_reqtfm
|
|
|
+!Finclude/linux/crypto.h crypto_ablkcipher_encrypt
|
|
|
+!Finclude/linux/crypto.h crypto_ablkcipher_decrypt
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Asynchronous Cipher Request Handle</title>
|
|
|
+!Pinclude/linux/crypto.h Asynchronous Cipher Request Handle
|
|
|
+!Finclude/linux/crypto.h crypto_ablkcipher_reqsize
|
|
|
+!Finclude/linux/crypto.h ablkcipher_request_set_tfm
|
|
|
+!Finclude/linux/crypto.h ablkcipher_request_alloc
|
|
|
+!Finclude/linux/crypto.h ablkcipher_request_free
|
|
|
+!Finclude/linux/crypto.h ablkcipher_request_set_callback
|
|
|
+!Finclude/linux/crypto.h ablkcipher_request_set_crypt
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Authenticated Encryption With Associated Data (AEAD) Cipher API</title>
|
|
|
+!Pinclude/linux/crypto.h Authenticated Encryption With Associated Data (AEAD) Cipher API
|
|
|
+!Finclude/linux/crypto.h crypto_alloc_aead
|
|
|
+!Finclude/linux/crypto.h crypto_free_aead
|
|
|
+!Finclude/linux/crypto.h crypto_aead_ivsize
|
|
|
+!Finclude/linux/crypto.h crypto_aead_authsize
|
|
|
+!Finclude/linux/crypto.h crypto_aead_blocksize
|
|
|
+!Finclude/linux/crypto.h crypto_aead_setkey
|
|
|
+!Finclude/linux/crypto.h crypto_aead_setauthsize
|
|
|
+!Finclude/linux/crypto.h crypto_aead_encrypt
|
|
|
+!Finclude/linux/crypto.h crypto_aead_decrypt
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Asynchronous AEAD Request Handle</title>
|
|
|
+!Pinclude/linux/crypto.h Asynchronous AEAD Request Handle
|
|
|
+!Finclude/linux/crypto.h crypto_aead_reqsize
|
|
|
+!Finclude/linux/crypto.h aead_request_set_tfm
|
|
|
+!Finclude/linux/crypto.h aead_request_alloc
|
|
|
+!Finclude/linux/crypto.h aead_request_free
|
|
|
+!Finclude/linux/crypto.h aead_request_set_callback
|
|
|
+!Finclude/linux/crypto.h aead_request_set_crypt
|
|
|
+!Finclude/linux/crypto.h aead_request_set_assoc
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Synchronous Block Cipher API</title>
|
|
|
+!Pinclude/linux/crypto.h Synchronous Block Cipher API
|
|
|
+!Finclude/linux/crypto.h crypto_alloc_blkcipher
|
|
|
+!Finclude/linux/crypto.h crypto_free_blkcipher
|
|
|
+!Finclude/linux/crypto.h crypto_has_blkcipher
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_name
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_ivsize
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_blocksize
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_setkey
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_encrypt
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_encrypt_iv
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_decrypt
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_decrypt_iv
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_set_iv
|
|
|
+!Finclude/linux/crypto.h crypto_blkcipher_get_iv
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Single Block Cipher API</title>
|
|
|
+!Pinclude/linux/crypto.h Single Block Cipher API
|
|
|
+!Finclude/linux/crypto.h crypto_alloc_cipher
|
|
|
+!Finclude/linux/crypto.h crypto_free_cipher
|
|
|
+!Finclude/linux/crypto.h crypto_has_cipher
|
|
|
+!Finclude/linux/crypto.h crypto_cipher_blocksize
|
|
|
+!Finclude/linux/crypto.h crypto_cipher_setkey
|
|
|
+!Finclude/linux/crypto.h crypto_cipher_encrypt_one
|
|
|
+!Finclude/linux/crypto.h crypto_cipher_decrypt_one
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Synchronous Message Digest API</title>
|
|
|
+!Pinclude/linux/crypto.h Synchronous Message Digest API
|
|
|
+!Finclude/linux/crypto.h crypto_alloc_hash
|
|
|
+!Finclude/linux/crypto.h crypto_free_hash
|
|
|
+!Finclude/linux/crypto.h crypto_has_hash
|
|
|
+!Finclude/linux/crypto.h crypto_hash_blocksize
|
|
|
+!Finclude/linux/crypto.h crypto_hash_digestsize
|
|
|
+!Finclude/linux/crypto.h crypto_hash_init
|
|
|
+!Finclude/linux/crypto.h crypto_hash_update
|
|
|
+!Finclude/linux/crypto.h crypto_hash_final
|
|
|
+!Finclude/linux/crypto.h crypto_hash_digest
|
|
|
+!Finclude/linux/crypto.h crypto_hash_setkey
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Message Digest Algorithm Definitions</title>
|
|
|
+!Pinclude/crypto/hash.h Message Digest Algorithm Definitions
|
|
|
+!Finclude/crypto/hash.h hash_alg_common
|
|
|
+!Finclude/crypto/hash.h ahash_alg
|
|
|
+!Finclude/crypto/hash.h shash_alg
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Asynchronous Message Digest API</title>
|
|
|
+!Pinclude/crypto/hash.h Asynchronous Message Digest API
|
|
|
+!Finclude/crypto/hash.h crypto_alloc_ahash
|
|
|
+!Finclude/crypto/hash.h crypto_free_ahash
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_init
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_digestsize
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_reqtfm
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_reqsize
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_setkey
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_finup
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_final
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_digest
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_export
|
|
|
+!Finclude/crypto/hash.h crypto_ahash_import
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Asynchronous Hash Request Handle</title>
|
|
|
+!Pinclude/crypto/hash.h Asynchronous Hash Request Handle
|
|
|
+!Finclude/crypto/hash.h ahash_request_set_tfm
|
|
|
+!Finclude/crypto/hash.h ahash_request_alloc
|
|
|
+!Finclude/crypto/hash.h ahash_request_free
|
|
|
+!Finclude/crypto/hash.h ahash_request_set_callback
|
|
|
+!Finclude/crypto/hash.h ahash_request_set_crypt
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Synchronous Message Digest API</title>
|
|
|
+!Pinclude/crypto/hash.h Synchronous Message Digest API
|
|
|
+!Finclude/crypto/hash.h crypto_alloc_shash
|
|
|
+!Finclude/crypto/hash.h crypto_free_shash
|
|
|
+!Finclude/crypto/hash.h crypto_shash_blocksize
|
|
|
+!Finclude/crypto/hash.h crypto_shash_digestsize
|
|
|
+!Finclude/crypto/hash.h crypto_shash_descsize
|
|
|
+!Finclude/crypto/hash.h crypto_shash_setkey
|
|
|
+!Finclude/crypto/hash.h crypto_shash_digest
|
|
|
+!Finclude/crypto/hash.h crypto_shash_export
|
|
|
+!Finclude/crypto/hash.h crypto_shash_import
|
|
|
+!Finclude/crypto/hash.h crypto_shash_init
|
|
|
+!Finclude/crypto/hash.h crypto_shash_update
|
|
|
+!Finclude/crypto/hash.h crypto_shash_final
|
|
|
+!Finclude/crypto/hash.h crypto_shash_finup
|
|
|
+ </sect1>
|
|
|
+ <sect1><title>Crypto API Random Number API</title>
|
|
|
+!Pinclude/crypto/rng.h Random number generator API
|
|
|
+!Finclude/crypto/rng.h crypto_alloc_rng
|
|
|
+!Finclude/crypto/rng.h crypto_rng_alg
|
|
|
+!Finclude/crypto/rng.h crypto_free_rng
|
|
|
+!Finclude/crypto/rng.h crypto_rng_get_bytes
|
|
|
+!Finclude/crypto/rng.h crypto_rng_reset
|
|
|
+!Finclude/crypto/rng.h crypto_rng_seedsize
|
|
|
+!Cinclude/crypto/rng.h
|
|
|
+ </sect1>
|
|
|
+ </chapter>
|
|
|
+
|
|
|
+ <chapter id="Code"><title>Code Examples</title>
|
|
|
+ <sect1><title>Code Example For Asynchronous Block Cipher Operation</title>
|
|
|
+ <programlisting>
|
|
|
+
|
|
|
+struct tcrypt_result {
|
|
|
+ struct completion completion;
|
|
|
+ int err;
|
|
|
+};
|
|
|
+
|
|
|
+/* tie all data structures together */
|
|
|
+struct ablkcipher_def {
|
|
|
+ struct scatterlist sg;
|
|
|
+ struct crypto_ablkcipher *tfm;
|
|
|
+ struct ablkcipher_request *req;
|
|
|
+ struct tcrypt_result result;
|
|
|
+};
|
|
|
+
|
|
|
+/* Callback function */
|
|
|
+static void test_ablkcipher_cb(struct crypto_async_request *req, int error)
|
|
|
+{
|
|
|
+ struct tcrypt_result *result = req->data;
|
|
|
+
|
|
|
+ if (error == -EINPROGRESS)
|
|
|
+ return;
|
|
|
+ result->err = error;
|
|
|
+ complete(&result->completion);
|
|
|
+ pr_info("Encryption finished successfully\n");
|
|
|
+}
|
|
|
+
|
|
|
+/* Perform cipher operation */
|
|
|
+static unsigned int test_ablkcipher_encdec(struct ablkcipher_def *ablk,
|
|
|
+ int enc)
|
|
|
+{
|
|
|
+ int rc = 0;
|
|
|
+
|
|
|
+ if (enc)
|
|
|
+ rc = crypto_ablkcipher_encrypt(ablk->req);
|
|
|
+ else
|
|
|
+ rc = crypto_ablkcipher_decrypt(ablk->req);
|
|
|
+
|
|
|
+ switch (rc) {
|
|
|
+ case 0:
|
|
|
+ break;
|
|
|
+ case -EINPROGRESS:
|
|
|
+ case -EBUSY:
|
|
|
+ rc = wait_for_completion_interruptible(
|
|
|
+ &ablk->result.completion);
|
|
|
+ if (!rc && !ablk->result.err) {
|
|
|
+ reinit_completion(&ablk->result.completion);
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ default:
|
|
|
+ pr_info("ablkcipher encrypt returned with %d result %d\n",
|
|
|
+ rc, ablk->result.err);
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ init_completion(&ablk->result.completion);
|
|
|
+
|
|
|
+ return rc;
|
|
|
+}
|
|
|
+
|
|
|
+/* Initialize and trigger cipher operation */
|
|
|
+static int test_ablkcipher(void)
|
|
|
+{
|
|
|
+ struct ablkcipher_def ablk;
|
|
|
+ struct crypto_ablkcipher *ablkcipher = NULL;
|
|
|
+ struct ablkcipher_request *req = NULL;
|
|
|
+ char *scratchpad = NULL;
|
|
|
+ char *ivdata = NULL;
|
|
|
+ unsigned char key[32];
|
|
|
+ int ret = -EFAULT;
|
|
|
+
|
|
|
+ ablkcipher = crypto_alloc_ablkcipher("cbc-aes-aesni", 0, 0);
|
|
|
+ if (IS_ERR(ablkcipher)) {
|
|
|
+ pr_info("could not allocate ablkcipher handle\n");
|
|
|
+ return PTR_ERR(ablkcipher);
|
|
|
+ }
|
|
|
+
|
|
|
+ req = ablkcipher_request_alloc(ablkcipher, GFP_KERNEL);
|
|
|
+ if (IS_ERR(req)) {
|
|
|
+ pr_info("could not allocate request queue\n");
|
|
|
+ ret = PTR_ERR(req);
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+
|
|
|
+ ablkcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
|
|
|
+ test_ablkcipher_cb,
|
|
|
+ &ablk.result);
|
|
|
+
|
|
|
+ /* AES 256 with random key */
|
|
|
+ get_random_bytes(&key, 32);
|
|
|
+ if (crypto_ablkcipher_setkey(ablkcipher, key, 32)) {
|
|
|
+ pr_info("key could not be set\n");
|
|
|
+ ret = -EAGAIN;
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+
|
|
|
+ /* IV will be random */
|
|
|
+ ivdata = kmalloc(16, GFP_KERNEL);
|
|
|
+ if (!ivdata) {
|
|
|
+ pr_info("could not allocate ivdata\n");
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+ get_random_bytes(ivdata, 16);
|
|
|
+
|
|
|
+ /* Input data will be random */
|
|
|
+ scratchpad = kmalloc(16, GFP_KERNEL);
|
|
|
+ if (!scratchpad) {
|
|
|
+ pr_info("could not allocate scratchpad\n");
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+ get_random_bytes(scratchpad, 16);
|
|
|
+
|
|
|
+ ablk.tfm = ablkcipher;
|
|
|
+ ablk.req = req;
|
|
|
+
|
|
|
+ /* We encrypt one block */
|
|
|
+ sg_init_one(&ablk.sg, scratchpad, 16);
|
|
|
+ ablkcipher_request_set_crypt(req, &ablk.sg, &ablk.sg, 16, ivdata);
|
|
|
+ init_completion(&ablk.result.completion);
|
|
|
+
|
|
|
+ /* encrypt data */
|
|
|
+ ret = test_ablkcipher_encdec(&ablk, 1);
|
|
|
+ if (ret)
|
|
|
+ goto out;
|
|
|
+
|
|
|
+ pr_info("Encryption triggered successfully\n");
|
|
|
+
|
|
|
+out:
|
|
|
+ if (ablkcipher)
|
|
|
+ crypto_free_ablkcipher(ablkcipher);
|
|
|
+ if (req)
|
|
|
+ ablkcipher_request_free(req);
|
|
|
+ if (ivdata)
|
|
|
+ kfree(ivdata);
|
|
|
+ if (scratchpad)
|
|
|
+ kfree(scratchpad);
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+ </programlisting>
|
|
|
+ </sect1>
|
|
|
+
|
|
|
+ <sect1><title>Code Example For Synchronous Block Cipher Operation</title>
|
|
|
+ <programlisting>
|
|
|
+
|
|
|
+static int test_blkcipher(void)
|
|
|
+{
|
|
|
+ struct crypto_blkcipher *blkcipher = NULL;
|
|
|
+ char *cipher = "cbc(aes)";
|
|
|
+ // AES 128
|
|
|
+ charkey =
|
|
|
+"\x12\x34\x56\x78\x90\xab\xcd\xef\x12\x34\x56\x78\x90\xab\xcd\xef";
|
|
|
+ chariv =
|
|
|
+"\x12\x34\x56\x78\x90\xab\xcd\xef\x12\x34\x56\x78\x90\xab\xcd\xef";
|
|
|
+ unsigned int ivsize = 0;
|
|
|
+ char *scratchpad = NULL; // holds plaintext and ciphertext
|
|
|
+ struct scatterlist sg;
|
|
|
+ struct blkcipher_desc desc;
|
|
|
+ int ret = -EFAULT;
|
|
|
+
|
|
|
+ blkcipher = crypto_alloc_blkcipher(cipher, 0, 0);
|
|
|
+ if (IS_ERR(blkcipher)) {
|
|
|
+ printk("could not allocate blkcipher handle for %s\n", cipher);
|
|
|
+ return -PTR_ERR(blkcipher);
|
|
|
+ }
|
|
|
+
|
|
|
+ if (crypto_blkcipher_setkey(blkcipher, key, strlen(key))) {
|
|
|
+ printk("key could not be set\n");
|
|
|
+ ret = -EAGAIN;
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+
|
|
|
+ ivsize = crypto_blkcipher_ivsize(blkcipher);
|
|
|
+ if (ivsize) {
|
|
|
+ if (ivsize != strlen(iv))
|
|
|
+ printk("IV length differs from expected length\n");
|
|
|
+ crypto_blkcipher_set_iv(blkcipher, iv, ivsize);
|
|
|
+ }
|
|
|
+
|
|
|
+ scratchpad = kmalloc(crypto_blkcipher_blocksize(blkcipher), GFP_KERNEL);
|
|
|
+ if (!scratchpad) {
|
|
|
+ printk("could not allocate scratchpad for %s\n", cipher);
|
|
|
+ goto out;
|
|
|
+ }
|
|
|
+ /* get some random data that we want to encrypt */
|
|
|
+ get_random_bytes(scratchpad, crypto_blkcipher_blocksize(blkcipher));
|
|
|
+
|
|
|
+ desc.flags = 0;
|
|
|
+ desc.tfm = blkcipher;
|
|
|
+ sg_init_one(&sg, scratchpad, crypto_blkcipher_blocksize(blkcipher));
|
|
|
+
|
|
|
+ /* encrypt data in place */
|
|
|
+ crypto_blkcipher_encrypt(&desc, &sg, &sg,
|
|
|
+ crypto_blkcipher_blocksize(blkcipher));
|
|
|
+
|
|
|
+ /* decrypt data in place
|
|
|
+ * crypto_blkcipher_decrypt(&desc, &sg, &sg,
|
|
|
+ */ crypto_blkcipher_blocksize(blkcipher));
|
|
|
+
|
|
|
+
|
|
|
+ printk("Cipher operation completed\n");
|
|
|
+ return 0;
|
|
|
+
|
|
|
+out:
|
|
|
+ if (blkcipher)
|
|
|
+ crypto_free_blkcipher(blkcipher);
|
|
|
+ if (scratchpad)
|
|
|
+ kzfree(scratchpad);
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+ </programlisting>
|
|
|
+ </sect1>
|
|
|
+
|
|
|
+ <sect1><title>Code Example For Use of Operational State Memory With SHASH</title>
|
|
|
+ <programlisting>
|
|
|
+
|
|
|
+struct sdesc {
|
|
|
+ struct shash_desc shash;
|
|
|
+ char ctx[];
|
|
|
+};
|
|
|
+
|
|
|
+static struct sdescinit_sdesc(struct crypto_shash *alg)
|
|
|
+{
|
|
|
+ struct sdescsdesc;
|
|
|
+ int size;
|
|
|
+
|
|
|
+ size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
|
|
|
+ sdesc = kmalloc(size, GFP_KERNEL);
|
|
|
+ if (!sdesc)
|
|
|
+ return ERR_PTR(-ENOMEM);
|
|
|
+ sdesc->shash.tfm = alg;
|
|
|
+ sdesc->shash.flags = 0x0;
|
|
|
+ return sdesc;
|
|
|
+}
|
|
|
+
|
|
|
+static int calc_hash(struct crypto_shashalg,
|
|
|
+ const unsigned chardata, unsigned int datalen,
|
|
|
+ unsigned chardigest) {
|
|
|
+ struct sdescsdesc;
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ sdesc = init_sdesc(alg);
|
|
|
+ if (IS_ERR(sdesc)) {
|
|
|
+ pr_info("trusted_key: can't alloc %s\n", hash_alg);
|
|
|
+ return PTR_ERR(sdesc);
|
|
|
+ }
|
|
|
+
|
|
|
+ ret = crypto_shash_digest(&sdesc->shash, data, datalen, digest);
|
|
|
+ kfree(sdesc);
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+ </programlisting>
|
|
|
+ </sect1>
|
|
|
+
|
|
|
+ <sect1><title>Code Example For Random Number Generator Usage</title>
|
|
|
+ <programlisting>
|
|
|
+
|
|
|
+static int get_random_numbers(u8 *buf, unsigned int len)
|
|
|
+{
|
|
|
+ struct crypto_rngrng = NULL;
|
|
|
+ chardrbg = "drbg_nopr_sha256"; /* Hash DRBG with SHA-256, no PR */
|
|
|
+ int ret;
|
|
|
+
|
|
|
+ if (!buf || !len) {
|
|
|
+ pr_debug("No output buffer provided\n");
|
|
|
+ return -EINVAL;
|
|
|
+ }
|
|
|
+
|
|
|
+ rng = crypto_alloc_rng(drbg, 0, 0);
|
|
|
+ if (IS_ERR(rng)) {
|
|
|
+ pr_debug("could not allocate RNG handle for %s\n", drbg);
|
|
|
+ return -PTR_ERR(rng);
|
|
|
+ }
|
|
|
+
|
|
|
+ ret = crypto_rng_get_bytes(rng, buf, len);
|
|
|
+ if (ret < 0)
|
|
|
+ pr_debug("generation of random numbers failed\n");
|
|
|
+ else if (ret == 0)
|
|
|
+ pr_debug("RNG returned no data");
|
|
|
+ else
|
|
|
+ pr_debug("RNG returned %d bytes of data\n", ret);
|
|
|
+
|
|
|
+out:
|
|
|
+ crypto_free_rng(rng);
|
|
|
+ return ret;
|
|
|
+}
|
|
|
+ </programlisting>
|
|
|
+ </sect1>
|
|
|
+ </chapter>
|
|
|
+ </book>
|