<?xml version="1.0" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>signature - Add a digital signature to the image</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link rev="made" href="mailto:bfriesen@freddy.simplesystems.org" /> </head> <body style="background-color: white"> <P><a name="__index__"></a></P> <!-- INDEX BEGIN --> <ul> <li><a href="#name">NAME</a></li> <li><a href="#synopsis">SYNOPSIS</a></li> <li><a href="#function_descriptions">FUNCTION DESCRIPTIONS</a></li> <ul> <li><a href="#finalizesignature">FinalizeSignature</a></li> <li><a href="#getsignatureinfo">GetSignatureInfo</a></li> <li><a href="#signatureimage">SignatureImage</a></li> <li><a href="#transformsignature">TransformSignature</a></li> <li><a href="#updatesignature">UpdateSignature</a></li> </ul> </ul> <!-- INDEX END --> <hr /> <P> </P> <h1><a name="name">NAME</a></h1> <P>signature - Add a digital signature to the image</P> <P> </P> <hr /> <h1><a name="synopsis">SYNOPSIS</a></h1> <P><strong>FinalizeSignature</strong>( SignatureInfo *signature_info );</P> <P><strong>GetSignatureInfo</strong>( SignatureInfo *signature_info );</P> <P>unsigned int <strong>SignatureImage</strong>( Image *image );</P> <P><strong>TransformSignature</strong>( SignatureInfo *signature_info );</P> <P><strong>UpdateSignature</strong>( SignatureInfo *signature_info, const unsigned char *message, const size_t length );</P> <P> </P> <hr /> <h1><a name="function_descriptions">FUNCTION DESCRIPTIONS</a></h1> <P> </P> <h2><a name="finalizesignature">FinalizeSignature</a></h2> <P>Method FinalizeSignature finalizes the SHA message digest computation.</P> <P>The format of the FinalizeSignature method is:</P> <blockquote>FinalizeSignature ( <A HREF="types.html#SignatureInfo">SignatureInfo</A> *signature_info ); </blockquote><P>A description of each parameter follows:</P> <dl> <dt><strong><a name="item_o_signature_info_3a">signature_info:</a></strong> <DD> <P>The address of a structure of type SignatureInfo.</P> </dd> </li> </dl> <P> </P> <h2><a name="getsignatureinfo">GetSignatureInfo</a></h2> <P>Method GetSignatureInfo initializes the SHA message digest structure.</P> <P>The format of the GetSignatureInfo method is:</P> <blockquote>GetSignatureInfo ( <A HREF="types.html#SignatureInfo">SignatureInfo</A> *signature_info ); </blockquote><P>A description of each parameter follows:</P> <dl> <dt><strong>signature_info:</strong> <DD> <P>The address of a structure of type SignatureInfo.</P> </dd> </li> </dl> <P> </P> <h2><a name="signatureimage">SignatureImage</a></h2> <blockquote>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. </blockquote><P>The format of the SignatureImage method is:</P> <blockquote>unsigned int SignatureImage ( <A HREF="types.html#Image">Image</A> *image ); </blockquote><P>A description of each parameter follows:</P> <dl> <dt><strong><a name="item_o_image_3a">image:</a></strong> <DD> <P>The image.</P> </dd> </li> </dl> <P> </P> <h2><a name="transformsignature">TransformSignature</a></h2> <blockquote>TransformSignature() transforms the SHA message digest. </blockquote><P>The format of the TransformSignature method is:</P> <blockquote>TransformSignature ( <A HREF="types.html#SignatureInfo">SignatureInfo</A> *signature_info ); </blockquote><P>A description of each parameter follows:</P> <dl> <dt><strong>signature_info:</strong> <DD> <P>The address of a structure of type SignatureInfo.</P> </dd> </li> </dl> <P> </P> <h2><a name="updatesignature">UpdateSignature</a></h2> <blockquote>UpdateSignature() updates the SHA message digest. </blockquote><P>The format of the UpdateSignature method is:</P> <blockquote>UpdateSignature ( <A HREF="types.html#SignatureInfo">SignatureInfo</A> *signature_info, const unsigned char *message, const size_t length ); </blockquote><P>A description of each parameter follows:</P> <dl> <dt><strong>signature_info:</strong> <DD> <P>The address of a structure of type SignatureInfo.</P> </dd> </li> <dt><strong><a name="item_o_message_3a">message:</a></strong> <DD> <P>the message</P> </dd> </li> <dt><strong><a name="item_o_length_3a">length:</a></strong> <DD> <P>The length of the message.</P> </dd> </dl> </body> </html>
