crypto: doc - remove crypto API DocBook

With the conversion of the documentation to Sphinx, the old DocBook is
now stale.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

2 files changed, 1 insertions, 2093 deletions

diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index caab9039362f..c75e5d6b8fa8 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -13,7 +13,7 @@ DOCBOOKS := z8530book.xml  \
 	    gadget.xml libata.xml mtdnand.xml librs.xml rapidio.xml \
 	    genericirq.xml s390-drivers.xml uio-howto.xml scsi.xml \
 	    80211.xml sh.xml regulator.xml w1.xml \
-	    writing_musb_glue_layer.xml crypto-API.xml iio.xml
+	    writing_musb_glue_layer.xml iio.xml
 
 ifeq ($(DOCBOOKS),)
 
diff --git a/Documentation/DocBook/crypto-API.tmpl b/Documentation/DocBook/crypto-API.tmpl
deleted file mode 100644
index 088b79c341ff..000000000000
--- a/Documentation/DocBook/crypto-API.tmpl
+++ /dev/null
@@ -1,2092 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
-	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<book id="KernelCryptoAPI">
- <bookinfo>
-  <title>Linux Kernel Crypto API</title>
-
-  <authorgroup>
-   <author>
-    <firstname>Stephan</firstname>
-    <surname>Mueller</surname>
-    <affiliation>
-     <address>
-      <email>smueller@chronox.de</email>
-     </address>
-    </affiliation>
-   </author>
-   <author>
-    <firstname>Marek</firstname>
-    <surname>Vasut</surname>
-    <affiliation>
-     <address>
-      <email>marek@denx.de</email>
-     </address>
-    </affiliation>
-   </author>
-  </authorgroup>
-
-  <copyright>
-   <year>2014</year>
-   <holder>Stephan Mueller</holder>
-  </copyright>
-
-
-  <legalnotice>
-   <para>
-     This documentation is free software; you can redistribute
-     it and/or modify it under the terms of the GNU General Public
-     License as published by the Free Software Foundation; either
-     version 2 of the License, or (at your option) any later
-     version.
-   </para>
-
-   <para>
-     This program is distributed in the hope that it will be
-     useful, but WITHOUT ANY WARRANTY; without even the implied
-     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-     See the GNU General Public License for more details.
-   </para>
-
-   <para>
-     You should have received a copy of the GNU General Public
-     License along with this program; if not, write to the Free
-     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
-     MA 02111-1307 USA
-   </para>
-
-   <para>
-     For more details see the file COPYING in the source
-     distribution of Linux.
-   </para>
-  </legalnotice>
- </bookinfo>
-
- <toc></toc>
-
- <chapter id="Intro">
-  <title>Kernel Crypto API Interface Specification</title>
-
-   <sect1><title>Introduction</title>
-
-    <para>
-     The kernel crypto API offers a rich set of cryptographic ciphers as
-     well as other data transformation mechanisms and methods to invoke
-     these. This document contains a description of the API and provides
-     example code.
-    </para>
-
-    <para>
-     To understand and properly use the kernel crypto API a brief
-     explanation of its structure is given. Based on the architecture,
-     the API can be separated into different components. Following the
-     architecture specification, hints to developers of ciphers are
-     provided. Pointers to the API function call  documentation are
-     given at the end.
-    </para>
-
-    <para>
-     The kernel crypto API refers to all algorithms as "transformations".
-     Therefore, a cipher handle variable usually has the name "tfm".
-     Besides cryptographic operations, the kernel crypto API also knows
-     compression transformations and handles them the same way as ciphers.
-    </para>
-
-    <para>
-     The kernel crypto API serves the following entity types:
-
-     <itemizedlist>
-      <listitem>
-       <para>consumers requesting cryptographic services</para>
-      </listitem>
-      <listitem>
-      <para>data transformation implementations (typically ciphers)
-       that can be called by consumers using the kernel crypto
-       API</para>
-      </listitem>
-     </itemizedlist>
-    </para>
-
-    <para>
-     This specification is intended for consumers of the kernel crypto
-     API as well as for developers implementing ciphers. This API
-     specification, however, does not discuss all API calls available
-     to data transformation implementations (i.e. implementations of
-     ciphers and other transformations (such as CRC or even compression
-     algorithms) that can register with the kernel crypto API).
-    </para>
-
-    <para>
-     Note: The terms "transformation" and cipher algorithm are used
-     interchangeably.
-    </para>
-   </sect1>
-
-   <sect1><title>Terminology</title>
-    <para>
-     The transformation implementation is an actual code or interface
-     to hardware which implements a certain transformation with precisely
-     defined behavior.
-    </para>
-
-    <para>
-     The transformation object (TFM) is an instance of a transformation
-     implementation. There can be multiple transformation objects
-     associated with a single transformation implementation. Each of
-     those transformation objects is held by a crypto API consumer or
-     another transformation. Transformation object is allocated when a
-     crypto API consumer requests a transformation implementation.
-     The consumer is then provided with a structure, which contains
-     a transformation object (TFM).
-    </para>
-
-    <para>
-     The structure that contains transformation objects may also be
-     referred to as a "cipher handle". Such a cipher handle is always
-     subject to the following phases that are reflected in the API calls
-     applicable to such a cipher handle:
-    </para>
-
-    <orderedlist>
-     <listitem>
-      <para>Initialization of a cipher handle.</para>
-     </listitem>
-     <listitem>
-      <para>Execution of all intended cipher operations applicable
-      for the handle where the cipher handle must be furnished to
-      every API call.</para>
-     </listitem>
-     <listitem>
-      <para>Destruction of a cipher handle.</para>
-     </listitem>
-    </orderedlist>
-
-    <para>
-     When using the initialization API calls, a cipher handle is
-     created and returned to the consumer. Therefore, please refer
-     to all initialization API calls that refer to the data
-     structure type a consumer is expected to receive and subsequently
-     to use. The initialization API calls have all the same naming
-     conventions of crypto_alloc_*.
-    </para>
-
-    <para>
-     The transformation context is private data associated with
-     the transformation object.
-    </para>
-   </sect1>
-  </chapter>
-
-  <chapter id="Architecture"><title>Kernel Crypto API Architecture</title>
-   <sect1><title>Cipher algorithm types</title>
-    <para>
-     The kernel crypto API provides different API calls for the
-     following cipher types:
-
-     <itemizedlist>
-      <listitem><para>Symmetric ciphers</para></listitem>
-      <listitem><para>AEAD ciphers</para></listitem>
-      <listitem><para>Message digest, including keyed message digest</para></listitem>
-      <listitem><para>Random number generation</para></listitem>
-      <listitem><para>User space interface</para></listitem>
-     </itemizedlist>
-    </para>
-   </sect1>
-
-   <sect1><title>Ciphers And Templates</title>
-    <para>
-     The kernel crypto API provides implementations of single block
-     ciphers and message digests. In addition, the kernel crypto API
-     provides numerous "templates" that can be used in conjunction
-     with the single block ciphers and message digests. Templates
-     include all types of block chaining mode, the HMAC mechanism, etc.
-    </para>
-
-    <para>
-     Single block ciphers and message digests can either be directly
-     used by a caller or invoked together with a template to form
-     multi-block ciphers or keyed message digests.
-    </para>
-
-    <para>
-     A single block cipher may even be called with multiple templates.
-     However, templates cannot be used without a single cipher.
-    </para>
-
-    <para>
-     See /proc/crypto and search for "name". For example:
-
-     <itemizedlist>
-      <listitem><para>aes</para></listitem>
-      <listitem><para>ecb(aes)</para></listitem>
-      <listitem><para>cmac(aes)</para></listitem>
-      <listitem><para>ccm(aes)</para></listitem>
-      <listitem><para>rfc4106(gcm(aes))</para></listitem>
-      <listitem><para>sha1</para></listitem>
-      <listitem><para>hmac(sha1)</para></listitem>
-      <listitem><para>authenc(hmac(sha1),cbc(aes))</para></listitem>
-     </itemizedlist>
-    </para>
-
-    <para>
-     In these examples, "aes" and "sha1" are the ciphers and all
-     others are the templates.
-    </para>
-   </sect1>
-
-   <sect1><title>Synchronous And Asynchronous Operation</title>
-    <para>
-     The kernel crypto API provides synchronous and asynchronous
-     API operations.
-    </para>
-
-    <para>
-     When using the synchronous API operation, the caller invokes
-     a cipher operation which is performed synchronously by the
-     kernel crypto API. That means, the caller waits until the
-     cipher operation completes. Therefore, the kernel crypto API
-     calls work like regular function calls. For synchronous
-     operation, the set of API calls is small and conceptually
-     similar to any other crypto library.
-    </para>
-
-    <para>
-     Asynchronous operation is provided by the kernel crypto API
-     which implies that the invocation of a cipher operation will
-     complete almost instantly. That invocation triggers the
-     cipher operation but it does not signal its completion. Before
-     invoking a cipher operation, the caller must provide a callback
-     function the kernel crypto API can invoke to signal the
-     completion of the cipher operation. Furthermore, the caller
-     must ensure it can handle such asynchronous events by applying
-     appropriate locking around its data. The kernel crypto API
-     does not perform any special serialization operation to protect
-     the caller's data integrity.
-    </para>
-   </sect1>
-
-   <sect1><title>Crypto API Cipher References And Priority</title>
-    <para>
-     A cipher is referenced by the caller with a string. That string
-     has the following semantics:
-
-     <programlisting>
-	template(single block cipher)
-     </programlisting>
-
-     where "template" and "single block cipher" is the aforementioned
-     template and single block cipher, respectively. If applicable,
-     additional templates may enclose other templates, such as
-
-      <programlisting>
-	template1(template2(single block cipher)))
-      </programlisting>
-    </para>
-
-    <para>
-     The kernel crypto API may provide multiple implementations of a
-     template or a single block cipher. For example, AES on newer
-     Intel hardware has the following implementations: AES-NI,
-     assembler implementation, or straight C. Now, when using the
-     string "aes" with the kernel crypto API, which cipher
-     implementation is used? The answer to that question is the
-     priority number assigned to each cipher implementation by the
-     kernel crypto API. When a caller uses the string to refer to a
-     cipher during initialization of a cipher handle, the kernel
-     crypto API looks up all implementations providing an
-     implementation with that name and selects the implementation
-     with the highest priority.
-    </para>
-
-    <para>
-     Now, a caller may have the need to refer to a specific cipher
-     implementation and thus does not want to rely on the
-     priority-based selection. To accommodate this scenario, the
-     kernel crypto API allows the cipher implementation to register
-     a unique name in addition to common names. When using that
-     unique name, a caller is therefore always sure to refer to
-     the intended cipher implementation.
-    </para>
-
-    <para>
-     The list of available ciphers is given in /proc/crypto. However,
-     that list does not specify all possible permutations of
-     templates and ciphers. Each block listed in /proc/crypto may
-     contain the following information -- if one of the components
-     listed as follows are not applicable to a cipher, it is not
-     displayed:
-    </para>
-
-    <itemizedlist>
-     <listitem>
-      <para>name: the generic name of the cipher that is subject
-       to the priority-based selection -- this name can be used by
-       the cipher allocation API calls (all names listed above are
-       examples for such generic names)</para>
-     </listitem>
-     <listitem>
-      <para>driver: the unique name of the cipher -- this name can
-       be used by the cipher allocation API calls</para>
-     </listitem>
-     <listitem>
-      <para>module: the kernel module providing the cipher
-       implementation (or "kernel" for statically linked ciphers)</para>
-     </listitem>
-     <listitem>
-      <para>priority: the priority value of the cipher implementation</para>
-     </listitem>
-     <listitem>
-      <para>refcnt: the reference count of the respective cipher
-       (i.e. the number of current consumers of this cipher)</para>
-     </listitem>
-     <listitem>
-      <para>selftest: specification whether the self test for the
-       cipher passed</para>
-     </listitem>
-     <listitem>
-      <para>type:
-       <itemizedlist>
-        <listitem>
-         <para>skcipher for symmetric key ciphers</para>
-        </listitem>
-        <listitem>
-         <para>cipher for single block ciphers that may be used with
-          an additional template</para>
-        </listitem>
-        <listitem>
-         <para>shash for synchronous message digest</para>
-        </listitem>
-        <listitem>
-         <para>ahash for asynchronous message digest</para>
-        </listitem>
-        <listitem>
-         <para>aead for AEAD cipher type</para>
-        </listitem>
-        <listitem>
-         <para>compression for compression type transformations</para>
-        </listitem>
-        <listitem>
-         <para>rng for random number generator</para>
-        </listitem>
-        <listitem>
-         <para>givcipher for cipher with associated IV generator
-          (see the geniv entry below for the specification of the
-          IV generator type used by the cipher implementation)</para>
-        </listitem>
-       </itemizedlist>
-      </para>
-     </listitem>
-     <listitem>
-      <para>blocksize: blocksize of cipher in bytes</para>
-     </listitem>
-     <listitem>
-      <para>keysize: key size in bytes</para>
-     </listitem>
-     <listitem>
-      <para>ivsize: IV size in bytes</para>
-     </listitem>
-     <listitem>
-      <para>seedsize: required size of seed data for random number
-       generator</para>
-     </listitem>
-     <listitem>
-      <para>digestsize: output size of the message digest</para>
-     </listitem>
-     <listitem>
-      <para>geniv: IV generation type:
-       <itemizedlist>
-        <listitem>
-         <para>eseqiv for encrypted sequence number based IV
-          generation</para>
-        </listitem>
-        <listitem>
-         <para>seqiv for sequence number based IV generation</para>
-        </listitem>
-        <listitem>
-         <para>chainiv for chain iv generation</para>
-        </listitem>
-        <listitem>
-         <para>&lt;builtin&gt; is a marker that the cipher implements
-          IV generation and handling as it is specific to the given
-          cipher</para>
-        </listitem>
-       </itemizedlist>
-      </para>
-     </listitem>
-    </itemizedlist>
-   </sect1>
-
-   <sect1><title>Key Sizes</title>
-    <para>
-     When allocating a cipher handle, the caller only specifies the
-     cipher type. Symmetric ciphers, however, typically support
-     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 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_AKCIPHER Asymmetric cipher</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>
-
-   <sect1><title>Internal Structure of Kernel Crypto API</title>
-
-    <para>
-     The kernel crypto API has an internal structure where a cipher
-     implementation may use many layers and indirections. This section
-     shall help to clarify how the kernel crypto API uses
-     various components to implement the complete cipher.
-    </para>
-
-    <para>
-     The following subsections explain the internal structure based
-     on existing cipher implementations. The first section addresses
-     the most complex scenario where all other scenarios form a logical
-     subset.
-    </para>
-
-    <sect2><title>Generic AEAD Cipher Structure</title>
-
-     <para>
-      The following ASCII art decomposes the kernel crypto API layers
-      when using the AEAD cipher with the automated IV generation. The
-      shown example is used by the IPSEC layer.
-     </para>
-
-     <para>
-      For other use cases of AEAD ciphers, the ASCII art applies as
-      well, but the caller may not use the AEAD cipher with a separate
-      IV generator. In this case, the caller must generate the IV.
-     </para>
-
-     <para>
-      The depicted example decomposes the AEAD cipher of GCM(AES) based
-      on the generic C implementations (gcm.c, aes-generic.c, ctr.c,
-      ghash-generic.c, seqiv.c). The generic implementation serves as an
-      example showing the complete logic of the kernel crypto API.
-     </para>
-
-     <para>
-      It is possible that some streamlined cipher implementations (like
-      AES-NI) provide implementations merging aspects which in the view
-      of the kernel crypto API cannot be decomposed into layers any more.
-      In case of the AES-NI implementation, the CTR mode, the GHASH
-      implementation and the AES cipher are all merged into one cipher
-      implementation registered with the kernel crypto API. In this case,
-      the concept described by the following ASCII art applies too. However,
-      the decomposition of GCM into the individual sub-components
-      by the kernel crypto API is not done any more.
-     </para>
-
-     <para>
-      Each block in the following ASCII art is an independent cipher
-      instance obtained from the kernel crypto API. Each block
-      is accessed by the caller or by other blocks using the API functions
-      defined by the kernel crypto API for the cipher implementation type.
-     </para>
-
-     <para>
-      The blocks below indicate the cipher type as well as the specific
-      logic implemented in the cipher.
-     </para>
-
-     <para>
-      The ASCII art picture also indicates the call structure, i.e. who
-      calls which component. The arrows point to the invoked block
-      where the caller uses the API applicable to the cipher type
-      specified for the block.
-     </para>
-
-     <programlisting>
-<![CDATA[
-kernel crypto API                                |   IPSEC Layer
-                                                 |
-+-----------+                                    |
-|           |            (1)
-|   aead    | <-----------------------------------  esp_output
-|  (seqiv)  | ---+
-+-----------+    |
-                 | (2)
-+-----------+    |
-|           | <--+                (2)
-|   aead    | <-----------------------------------  esp_input
-|   (gcm)   | ------------+
-+-----------+             |
-      | (3)               | (5)
-      v                   v
-+-----------+       +-----------+
-|           |       |           |
-|  skcipher |       |   ahash   |
-|   (ctr)   | ---+  |  (ghash)  |
-+-----------+    |  +-----------+
-                 |
-+-----------+    | (4)
-|           | <--+
-|   cipher  |
-|   (aes)   |
-+-----------+
-]]>
-     </programlisting>
-
-     <para>
-      The following call sequence is applicable when the IPSEC layer
-      triggers an encryption operation with the esp_output function. During
-      configuration, the administrator set up the use of rfc4106(gcm(aes)) as
-      the cipher for ESP. The following call sequence is now depicted in the
-      ASCII art above:
-     </para>
-
-     <orderedlist>
-      <listitem>
-       <para>
-        esp_output() invokes crypto_aead_encrypt() to trigger an encryption
-        operation of the AEAD cipher with IV generator.
-       </para>
-
-       <para>
-        In case of GCM, the SEQIV implementation is registered as GIVCIPHER
-        in crypto_rfc4106_alloc().
-       </para>
-
-       <para>
-        The SEQIV performs its operation to generate an IV where the core
-        function is seqiv_geniv().
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        Now, SEQIV uses the AEAD API function calls to invoke the associated
-        AEAD cipher. In our case, during the instantiation of SEQIV, the
-        cipher handle for GCM is provided to SEQIV. This means that SEQIV
-        invokes AEAD cipher operations with the GCM cipher handle.
-       </para>
-
-       <para>
-        During instantiation of the GCM handle, the CTR(AES) and GHASH
-        ciphers are instantiated. The cipher handles for CTR(AES) and GHASH
-        are retained for later use.
-       </para>
-
-       <para>
-        The GCM implementation is responsible to invoke the CTR mode AES and
-        the GHASH cipher in the right manner to implement the GCM
-        specification.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The GCM AEAD cipher type implementation now invokes the SKCIPHER API
-        with the instantiated CTR(AES) cipher handle.
-       </para>
-
-       <para>
-	During instantiation of the CTR(AES) cipher, the CIPHER type
-	implementation of AES is instantiated. The cipher handle for AES is
-	retained.
-       </para>
-
-       <para>
-        That means that the SKCIPHER implementation of CTR(AES) only
-        implements the CTR block chaining mode. After performing the block
-        chaining operation, the CIPHER implementation of AES is invoked.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The SKCIPHER of CTR(AES) now invokes the CIPHER API with the AES
-        cipher handle to encrypt one block.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The GCM AEAD implementation also invokes the GHASH cipher
-        implementation via the AHASH API.
-       </para>
-      </listitem>
-     </orderedlist>
-
-     <para>
-      When the IPSEC layer triggers the esp_input() function, the same call
-      sequence is followed with the only difference that the operation starts
-      with step (2).
-     </para>
-    </sect2>
-
-    <sect2><title>Generic Block Cipher Structure</title>
-     <para>
-      Generic block ciphers follow the same concept as depicted with the ASCII
-      art picture above.
-     </para>
-
-     <para>
-      For example, CBC(AES) is implemented with cbc.c, and aes-generic.c. The
-      ASCII art picture above applies as well with the difference that only
-      step (4) is used and the SKCIPHER block chaining mode is CBC.
-     </para>
-    </sect2>
-
-    <sect2><title>Generic Keyed Message Digest Structure</title>
-     <para>
-      Keyed message digest implementations again follow the same concept as
-      depicted in the ASCII art picture above.
-     </para>
-
-     <para>
-      For example, HMAC(SHA256) is implemented with hmac.c and
-      sha256_generic.c. The following ASCII art illustrates the
-      implementation:
-     </para>
-
-     <programlisting>
-<![CDATA[
-kernel crypto API            |       Caller
-                             |
-+-----------+         (1)    |
-|           | <------------------  some_function
-|   ahash   |
-|   (hmac)  | ---+
-+-----------+    |
-                 | (2)
-+-----------+    |
-|           | <--+
-|   shash   |
-|  (sha256) |
-+-----------+
-]]>
-     </programlisting>
-
-     <para>
-      The following call sequence is applicable when a caller triggers
-      an HMAC operation:
-     </para>
-
-     <orderedlist>
-      <listitem>
-       <para>
-        The AHASH API functions are invoked by the caller. The HMAC
-        implementation performs its operation as needed.
-       </para>
-
-       <para>
-        During initialization of the HMAC cipher, the SHASH cipher type of
-        SHA256 is instantiated. The cipher handle for the SHA256 instance is
-        retained.
-       </para>
-
-       <para>
-        At one time, the HMAC implementation requires a SHA256 operation
-        where the SHA256 cipher handle is used.
-       </para>
-      </listitem>
-
-      <listitem>
-       <para>
-        The HMAC instance now invokes the SHASH API with the SHA256
-        cipher handle to calculate the message digest.
-       </para>
-      </listitem>
-     </orderedlist>
-    </sect2>
-   </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,
-     for example when a driver implements multiple transformations.
-    </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 &lt; 0 implies
-     an error.
-    </para>
-
-    <para>
-     The bulk registration/unregistration functions
-     register/unregister each transformation in the given array of
-     length count.  They handle errors as follows:
-    </para>
-    <itemizedlist>
-     <listitem>
-      <para>
-       crypto_register_algs() succeeds if and only if it
-       successfully registers all the given transformations. If an
-       error occurs partway through, then it rolls back successful
-       registrations before returning the error code. Note that if
-       a driver needs to handle registration errors for individual
-       transformations, then it will need to use the non-bulk
-       function crypto_register_alg() instead.
-      </para>
-     </listitem>
-     <listitem>
-      <para>
-       crypto_unregister_algs() tries to unregister all the given
-       transformations, continuing on error. It logs errors and
-       always returns zero.
-      </para>
-     </listitem>
-    </itemizedlist>
-
-   </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() -&gt; .cia_encrypt()
-                                  |
-                                  '-----&gt; 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() -&gt; .cia_encrypt() -&gt; .cia_setkey() -&gt; .cia_encrypt()
-                           |                                  |
-                           '---&gt; CIPHERTEXT1                  '---&gt; CIPHERTEXT2
-      </programlisting>
-     </para>
-
-    </sect2>
-   </sect1>
-
-   <sect1><title>Multi-Block Ciphers</title>
-    <para>
-     Example of transformations: cbc(aes), ecb(arc4), ...
-    </para>
-
-    <para>
-     This section describes the multi-block cipher transformation
-     implementations. 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>