<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="Docutils 0.15.2: http://docutils.sourceforge.net/" /> <title>signature</title> <link rel="stylesheet" href="../docutils-api.css" type="text/css" /> </head> <body> <div class="banner"> <img src="../images/gm-107x76.png" alt="GraphicMagick logo" width="107" height="76" /> <span class="title">GraphicsMagick</span> <form action="http://www.google.com/search"> <input type="hidden" name="domains" value="www.graphicsmagick.org" /> <input type="hidden" name="sitesearch" value="www.graphicsmagick.org" /> <span class="nowrap"><input type="text" name="q" size="25" maxlength="255" /> <input type="submit" name="sa" value="Search" /></span> </form> </div> <div class="navmenu"> <ul> <li><a href="../index.html">Home</a></li> <li><a href="../project.html">Project</a></li> <li><a href="../download.html">Download</a></li> <li><a href="../README.html">Install</a></li> <li><a href="../Hg.html">Source</a></li> <li><a href="../NEWS.html">News</a> </li> <li><a href="../utilities.html">Utilities</a></li> <li><a href="../programming.html">Programming</a></li> <li><a href="../reference.html">Reference</a></li> </ul> </div> <div class="document" id="signature"> <h1 class="title">signature</h1> <h2 class="subtitle" id="add-a-digital-signature-to-the-image">Add a digital signature to the image</h2> <div class="contents topic" id="contents"> <p class="topic-title first">Contents</p> <ul class="simple"> <li><a class="reference internal" href="#finalizesignature" id="id9">FinalizeSignature</a></li> <li><a class="reference internal" href="#getsignatureinfo" id="id10">GetSignatureInfo</a></li> <li><a class="reference internal" href="#signatureimage" id="id11">SignatureImage</a></li> <li><a class="reference internal" href="#transformsignature" id="id12">TransformSignature</a></li> <li><a class="reference internal" href="#updatesignature" id="id13">UpdateSignature</a></li> </ul> </div> <div class="section" id="finalizesignature"> <h1><a class="toc-backref" href="#id9">FinalizeSignature</a></h1> <div class="section" id="synopsis"> <h2>Synopsis</h2> <pre class="literal-block"> FinalizeSignature( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info ); </pre> </div> <div class="section" id="description"> <h2>Description</h2> <p>Method FinalizeSignature finalizes the SHA message digest computation.</p> <p>The format of the FinalizeSignature method is:</p> <pre class="literal-block"> FinalizeSignature( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info ); </pre> <p>A description of each parameter follows:</p> <dl class="docutils"> <dt>signature_info:</dt> <dd>The address of a structure of type SignatureInfo.</dd> </dl> </div> </div> <div class="section" id="getsignatureinfo"> <h1><a class="toc-backref" href="#id10">GetSignatureInfo</a></h1> <div class="section" id="id1"> <h2>Synopsis</h2> <pre class="literal-block"> GetSignatureInfo( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info ); </pre> </div> <div class="section" id="id2"> <h2>Description</h2> <p>Method GetSignatureInfo initializes the SHA message digest structure.</p> <p>The format of the GetSignatureInfo method is:</p> <pre class="literal-block"> GetSignatureInfo( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info ); </pre> <p>A description of each parameter follows:</p> <dl class="docutils"> <dt>signature_info:</dt> <dd>The address of a structure of type SignatureInfo.</dd> </dl> </div> </div> <div class="section" id="signatureimage"> <h1><a class="toc-backref" href="#id11">SignatureImage</a></h1> <div class="section" id="id3"> <h2>Synopsis</h2> <pre class="literal-block"> unsigned int SignatureImage( <a class="reference external" href="../api/types.html#image">Image</a> *image ); </pre> </div> <div class="section" id="id4"> <h2>Description</h2> <p>SignatureImage() computes a message digest from an image pixel stream with an implementation of the NIST SHA-256 Message Digest algorithm. This signature uniquely identifies the image and is convenient for determining if an image has been modified or whether two images are identical.</p> <p>The format of the SignatureImage method is:</p> <pre class="literal-block"> unsigned int SignatureImage( <a class="reference external" href="../api/types.html#image">Image</a> *image ); </pre> <p>A description of each parameter follows:</p> <dl class="docutils"> <dt>image:</dt> <dd>The image.</dd> </dl> </div> </div> <div class="section" id="transformsignature"> <h1><a class="toc-backref" href="#id12">TransformSignature</a></h1> <div class="section" id="id5"> <h2>Synopsis</h2> <pre class="literal-block"> TransformSignature( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info ); </pre> </div> <div class="section" id="id6"> <h2>Description</h2> <p>TransformSignature() transforms the SHA message digest.</p> <p>The format of the TransformSignature method is:</p> <pre class="literal-block"> TransformSignature( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info ); </pre> <p>A description of each parameter follows:</p> <dl class="docutils"> <dt>signature_info:</dt> <dd>The address of a structure of type SignatureInfo.</dd> </dl> </div> </div> <div class="section" id="updatesignature"> <h1><a class="toc-backref" href="#id13">UpdateSignature</a></h1> <div class="section" id="id7"> <h2>Synopsis</h2> <pre class="literal-block"> UpdateSignature( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info, const unsigned char *message, const size_t length ); </pre> </div> <div class="section" id="id8"> <h2>Description</h2> <p>UpdateSignature() updates the SHA message digest.</p> <p>The format of the UpdateSignature method is:</p> <pre class="literal-block"> UpdateSignature( <a class="reference external" href="../api/types.html#signatureinfo">SignatureInfo</a> *signature_info, const unsigned char *message, const size_t length ); </pre> <dl class="docutils"> <dt>signature_info:</dt> <dd>The address of a structure of type SignatureInfo.</dd> <dt>message:</dt> <dd>the message</dd> <dt>length:</dt> <dd>The length of the message.</dd> </dl> </div> </div> </div> </body> </html>