gnupg/doc/gcryptref-cipher.sgml

<!-- gcryptref-cipher.sgml - libgcrypt reference (ciphers)
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-->

<!--**********************************************
***********  cipher open, close  *****************
***********************************************-->
<refentry>
  <refnamediv>
    <refname>gcry_cipher_open</refname>
    <refname>gcry_cipher_close</refname>
    <refpurpose>create and destroy an encryption context</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>
      #include &lt;gcrypt.h&gt;
      </funcsynopsisinfo>
      <funcprototype>
	<funcdef>GCRY_CIPHER_HD <function>gcry_cipher_open</function></funcdef>
	<paramdef>int <parameter>algo</parameter></paramdef>
	<paramdef>int <parameter>mode</parameter></paramdef>
	<paramdef>unsigned in <parameter>flags</parameter></paramdef>
      </funcprototype>
      <funcprototype>
	<funcdef>void <function>gcry_cipher_close</function></funcdef>
	<paramdef>GCRY_CIPHER_HD <parameter>h</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>


  <refsect1><title>Description</title>
  <para>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_open</secondary>
	     </indexterm>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_close</secondary>
	     </indexterm>
  <function>gcry_cipher_open</function> creates the context required for
  most of the cipher functions.
  </para>
</refentry>


<!--**********************************************
***********  cipher control  *********************
***********************************************-->
<refentry>
  <refnamediv>
    <refname>gcry_cipher_ctl</refname>
    <refname>gcry_cipher_setkey</refname>
    <refname>gcry_cipher_setiv</refname>
    <refname>gcry_cipher_setiv</refname>
    <refpurpose>control cipher functions</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>
      #include &lt;gcrypt.h&gt;
      </funcsynopsisinfo>
      <funcprototype>
	<funcdef>int <function>gcry_cipher_ctl</function></funcdef>
	<paramdef>GCRY_CIPHER_HD <parameter>h</parameter></paramdef>
	<paramdef>int <parameter>cmd</parameter></paramdef>
	<paramdef>void *<parameter>buffer</parameter></paramdef>
	<paramdef>size_t <parameter>buflen</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>


  <refsect1><title>Description</title>
  <para>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_ctl</secondary>
	     </indexterm>
  <function>gcry_cipher_ctl</function> controls various aspects of the
  cipher module and specific cipher contexts.  A couple of macros may
  be used for convenience:

  gcry_cipher_setkey(h,k,l)
  gcry_cipher_setiv(h,k,l)
  gcry_cipher_sync(h)

  </para>
</refentry>


<!--**********************************************
***********  cipher info   ***********************
***********************************************-->
<refentry>
  <refnamediv>
    <refname>gcry_cipher_info</refname>
    <refpurpose>return information about a cipher context</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>
      #include &lt;gcrypt.h&gt;
      </funcsynopsisinfo>
      <funcprototype>
	<funcdef>int <function>gcry_cipher_info</function></funcdef>
	<paramdef>GCRY_CIPHER_HD <parameter>h</parameter></paramdef>
	<paramdef>int <parameter>what</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>


  <refsect1><title>Description</title>
  <para>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_info</secondary>
	     </indexterm>
  <function>gcry_cipher_info</function> is used to retrieve various
  information about a cipher context or the cipher module in general.
  Currently no information is available.
  </para>
</refentry>


<!--**********************************************
***********  cipher algo name	******************
***********************************************-->
<refentry>
  <refnamediv>
    <refname>gcry_cipher_algo_name</refname>
    <refpurpose>return the name of a cipher algorithm</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>
      #include &lt;gcrypt.h&gt;
      </funcsynopsisinfo>
      <funcprototype>
	<funcdef>const char *<function>gcry_cipher_algo_name</function></funcdef>
	<paramdef>int <parameter>algo</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>


  <refsect1><title>Description</title>
  <para>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_algo_name</secondary>
	     </indexterm>
  <function>gcry_cipher_algo_name</function> returns a string with the
  name of the cipher algorithm <parameter>algo</parameter>.  If the algorithm
  is not known or an other error occured, an empty string is return.  This
  function will never return NULL.
  </para>
</refentry>

<!--**********************************************
***********  cipher map name  ********************
***********************************************-->
<refentry>
  <refnamediv>
    <refname>gcry_cipher_map_name</refname>
    <refpurpose>return an algorithm identifier for string</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>
      #include &lt;gcrypt.h&gt;
      </funcsynopsisinfo>
      <funcprototype>
	<funcdef>int <function>gcry_cipher_map_name</function></funcdef>
	<paramdef>const char *<parameter>name</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>


  <refsect1><title>Description</title>
  <para>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_map_name</secondary>
	     </indexterm>
  <function>gcry_cipher_map_name</function> returns the algorithm identifier
  for the cipher algorithm described by the string <parameter>name</parameter>.
  If this algorith is not available 0 is returned.
  </para>
</refentry>

<!--**********************************************
***********  cipher en/decryptlose  **************
***********************************************-->
<refentry>
  <refnamediv>
    <refname>gcry_cipher_encrypt</refname>
    <refname>gcry_cipher_decrypt</refname>
    <refpurpose>encrypt data or decrypt data</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcsynopsisinfo>
      #include &lt;gcrypt.h&gt;
      </funcsynopsisinfo>
      <funcprototype>
	<funcdef>int <function>gcry_cipher_encrypt</function></funcdef>
	<paramdef>GCRY_CIPHER_HD <parameter>h</parameter></paramdef>
	<paramdef>unsigned char <parameter>out</parameter></paramdef>
	<paramdef>size_t <parameter>outsize</parameter></paramdef>
	<paramdef>unsigned char <parameter>in</parameter></paramdef>
	<paramdef>size_t <parameter>insize</parameter></paramdef>
      </funcprototype>
      <funcprototype>
	<funcdef>int <function>gcry_cipher_decrypt</function></funcdef>
	<paramdef>GCRY_CIPHER_HD <parameter>h</parameter></paramdef>
	<paramdef>unsigned char <parameter>out</parameter></paramdef>
	<paramdef>size_t <parameter>outsize</parameter></paramdef>
	<paramdef>unsigned char <parameter>in</parameter></paramdef>
	<paramdef>size_t <parameter>insize</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>


  <refsect1><title>Description</title>
  <para>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_encrypt</secondary>
	     </indexterm>
  <indexterm><primary>cipher functions</primary>
	     <secondary>gcry_cipher_decrypt</secondary>
	     </indexterm>
  <function>gcry_cipher_encrypt</function> is used to encrypt the data.
  the complemetary function <function>gcry_cipher_decrypt</function> is
  be used to decrypt the data. The calling convention for both functions
  is the same.
  </para>
  <para>These functions can either work in place or with two buffers.
  Overlapping buffers are not allowed.
  </para>
</refentry>