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[Dcplusplus-commit] SF.net SVN: adc:[119] trunk
|
From: <ul...@us...> - 2014-01-19 16:29:22
|
Revision: 119
http://sourceforge.net/p/adc/code/119
Author: ullner
Date: 2014-01-19 16:29:18 +0000 (Sun, 19 Jan 2014)
Log Message:
-----------
Add Tiger and Merkle tree papers
Modified Paths:
--------------
trunk/ADC.txt
Added Paths:
-----------
trunk/Hashes/
trunk/Hashes/Tiger/
trunk/Hashes/Tiger/draft-jchapweske-thex-02.html
trunk/Hashes/Tiger/node1.html
trunk/Hashes/Tiger/node2.html
trunk/Hashes/Tiger/node3.html
trunk/Hashes/Tiger/node4.html
trunk/Hashes/Tiger/node5.html
trunk/Hashes/Tiger/node6.html
trunk/Hashes/Tiger/node7.html
trunk/Hashes/Tiger/node8.html
trunk/Hashes/Tiger/tiger.html
Modified: trunk/ADC.txt
===================================================================
--- trunk/ADC.txt 2014-01-19 16:27:04 UTC (rev 118)
+++ trunk/ADC.txt 2014-01-19 16:29:18 UTC (rev 119)
@@ -921,7 +921,7 @@
|=====
|Example |Description
|IQUI BBBB |A QUI that is sent from the hub indicating that the client BBBB has disconnected.
-|IQUI BBBB IDCCCC MSCats\sare\horrible DI1 TL-1 |A QUI that is sent from the hub indicating that the client BBBB has disconnected. The originator of the action is the client with the SID CCCC. The message "Cats are horrible" is included. All clients should terminate their connections with the client BBBB (DI1). The client should never attempt to reconnect (TL-1).
+|IQUI BBBB IDCCCC MSCats\sare\shorrible DI1 TL-1 |A QUI that is sent from the hub indicating that the client BBBB has disconnected. The originator of the action is the client with the SID CCCC. The message "Cats are horrible" is included. All clients should terminate their connections with the client BBBB (DI1). The client should never attempt to reconnect (TL-1).
|=====
==== GET
Added: trunk/Hashes/Tiger/draft-jchapweske-thex-02.html
===================================================================
--- trunk/Hashes/Tiger/draft-jchapweske-thex-02.html (rev 0)
+++ trunk/Hashes/Tiger/draft-jchapweske-thex-02.html 2014-01-19 16:29:18 UTC (rev 119)
@@ -0,0 +1,878 @@
+<html><head>
+
+<script type="text/javascript" src="/static/js/analytics.js" ></script>
+<link type="text/css" rel="stylesheet" href="/static/css/banner-styles.css"/>
+
+
+
+<title>Tree Hash EXchange format (THEX)</title>
+<meta http-equiv="Expires" content="Tue, 04 Mar 2003 22:41:32 +0000">
+<STYLE type='text/css'>
+ .title { color: #990000; font-size: 22px; line-height: 22px; font-weight: bold; text-align: right;
+ font-family: helvetica, arial, sans-serif }
+ .filename { color: #666666; font-size: 18px; line-height: 28px; font-weight: bold; text-align: right;
+ font-family: helvetica, arial, sans-serif }
+ p.copyright { color: #000000; font-size: 10px;
+ font-family: verdana, charcoal, helvetica, arial, sans-serif }
+ p { margin-left: 2em; margin-right: 2em; }
+ li { margin-left: 3em; }
+ ol { margin-left: 2em; margin-right: 2em; }
+ ul.text { margin-left: 2em; margin-right: 2em; }
+ pre { margin-left: 3em; color: #333333 }
+ ul.toc { color: #000000; line-height: 16px;
+ font-family: verdana, charcoal, helvetica, arial, sans-serif }
+ H3 { color: #333333; font-size: 16px; line-height: 16px; font-family: helvetica, arial, sans-serif }
+ H4 { color: #000000; font-size: 14px; font-family: helvetica, arial, sans-serif }
+ TD.header { color: #ffffff; font-size: 10px; font-family: arial, helvetica, san-serif; valign: top }
+ TD.author-text { color: #000000; font-size: 10px;
+ font-family: verdana, charcoal, helvetica, arial, sans-serif }
+ TD.author { color: #000000; font-weight: bold; margin-left: 4em; font-size: 10px; font-family: verdana, charcoal, helvetica, arial, sans-serif }
+ A:link { color: #990000; font-weight: bold;
+ font-family: MS Sans Serif, verdana, charcoal, helvetica, arial, sans-serif }
+ A:visited { color: #333333; font-weight: bold;
+ font-family: MS Sans Serif, verdana, charcoal, helvetica, arial, sans-serif }
+ A:name { color: #333333; font-weight: bold;
+ font-family: MS Sans Serif, verdana, charcoal, helvetica, arial, sans-serif }
+ .link2 { color:#ffffff; font-weight: bold; text-decoration: none;
+ font-family: monaco, charcoal, geneva, MS Sans Serif, helvetica, monotype, verdana, sans-serif;
+ font-size: 9px }
+ .RFC { color:#666666; font-weight: bold; text-decoration: none;
+ font-family: monaco, charcoal, geneva, MS Sans Serif, helvetica, monotype, verdana, sans-serif;
+ font-size: 9px }
+ .hotText { color:#ffffff; font-weight: normal; text-decoration: none;
+ font-family: charcoal, monaco, geneva, MS Sans Serif, helvetica, monotype, verdana, sans-serif;
+ font-size: 9px }
+</style>
+</head>
+<body bgcolor="#ffffff" text="#000000" alink="#000000" vlink="#666666" link="#990000">
+<!-- BEGIN WAYBACK TOOLBAR INSERT -->
+<script> if (window.archive_analytics) { window.archive_analytics.values['server_name']="wwwb-app19.us.archive.org";}; </script>
+
+<script type="text/javascript" src="/static/js/disclaim-element.js" ></script>
+<script type="text/javascript" src="/static/js/graph-calc.js" ></script>
+<script type="text/javascript" src="/static/jflot/jquery.min.js" ></script>
+<script type="text/javascript">
+//<![CDATA[
+var firstDate = 820454400000;
+var lastDate = 1420070399999;
+var wbPrefix = "/web/";
+var wbCurrentUrl = "http:\/\/www.open-content.net\/specs\/draft-jchapweske-thex-02.html";
+
+var curYear = -1;
+var curMonth = -1;
+var yearCount = 18;
+var firstYear = 1996;
+var imgWidth = 475;
+var yearImgWidth = 25;
+var monthImgWidth = 2;
+var trackerVal = "none";
+var displayDay = "16";
+var displayMonth = "mar";
+var displayYear = "2008";
+var prettyMonths = ["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"];
+
+function showTrackers(val) {
+ if(val == trackerVal) {
+ return;
+ }
+ if(val == "inline") {
+ document.getElementById("displayYearEl").style.color = "#ec008c";
+ document.getElementById("displayMonthEl").style.color = "#ec008c";
+ document.getElementById("displayDayEl").style.color = "#ec008c";
+ } else {
+ document.getElementById("displayYearEl").innerHTML = displayYear;
+ document.getElementById("displayYearEl").style.color = "#ff0";
+ document.getElementById("displayMonthEl").innerHTML = displayMonth;
+ document.getElementById("displayMonthEl").style.color = "#ff0";
+ document.getElementById("displayDayEl").innerHTML = displayDay;
+ document.getElementById("displayDayEl").style.color = "#ff0";
+ }
+ document.getElementById("wbMouseTrackYearImg").style.display = val;
+ document.getElementById("wbMouseTrackMonthImg").style.display = val;
+ trackerVal = val;
+}
+function getElementX2(obj) {
+ var thing = jQuery(obj);
+ if((thing == undefined)
+ || (typeof thing == "undefined")
+ || (typeof thing.offset == "undefined")) {
+ return getElementX(obj);
+ }
+ return Math.round(thing.offset().left);
+}
+function trackMouseMove(event,element) {
+
+ var eventX = getEventX(event);
+ var elementX = getElementX2(element);
+ var xOff = eventX - elementX;
+ if(xOff < 0) {
+ xOff = 0;
+ } else if(xOff > imgWidth) {
+ xOff = imgWidth;
+ }
+ var monthOff = xOff % yearImgWidth;
+
+ var year = Math.floor(xOff / yearImgWidth);
+ var yearStart = year * yearImgWidth;
+ var monthOfYear = Math.floor(monthOff / monthImgWidth);
+ if(monthOfYear > 11) {
+ monthOfYear = 11;
+ }
+ // 1 extra border pixel at the left edge of the year:
+ var month = (year * 12) + monthOfYear;
+ var day = 1;
+ if(monthOff % 2 == 1) {
+ day = 15;
+ }
+ var dateString =
+ zeroPad(year + firstYear) +
+ zeroPad(monthOfYear+1,2) +
+ zeroPad(day,2) + "000000";
+
+ var monthString = prettyMonths[monthOfYear];
+ document.getElementById("displayYearEl").innerHTML = year + 1996;
+ document.getElementById("displayMonthEl").innerHTML = monthString;
+ // looks too jarring when it changes..
+ //document.getElementById("displayDayEl").innerHTML = zeroPad(day,2);
+
+ var url = wbPrefix + dateString + '/' + wbCurrentUrl;
+ document.getElementById('wm-graph-anchor').href = url;
+
+ //document.getElementById("wmtbURL").value="evX("+eventX+") elX("+elementX+") xO("+xOff+") y("+year+") m("+month+") monthOff("+monthOff+") DS("+dateString+") Moy("+monthOfYear+") ms("+monthString+")";
+ if(curYear != year) {
+ var yrOff = year * yearImgWidth;
+ document.getElementById("wbMouseTrackYearImg").style.left = yrOff + "px";
+ curYear = year;
+ }
+ if(curMonth != month) {
+ var mtOff = year + (month * monthImgWidth) + 1;
+ document.getElementById("wbMouseTrackMonthImg").style.left = mtOff + "px";
+ curMonth = month;
+ }
+}
+//]]>
+</script>
+
+<style type="text/css">body{margin-top:0!important;padding-top:0!important;min-width:800px!important;}#wm-ipp a:hover{text-decoration:underline!important;}</style>
+<div id="wm-ipp" lang="en" class="__wb_banner_div" style="display:none; position:relative;padding:0 5px;min-height:70px;min-width:800px">
+
+
+<div id="wm-ipp-inside" class="__wb_banner_div" style="position:fixed;padding:0!important;margin:0!important;width:97%;min-width:780px;border:5px solid #000;border-top:none;background-image:url(/static/images/toolbar/wm_tb_bk_trns.png);text-align:center;-moz-box-shadow:1px 1px 3px #333;-webkit-box-shadow:1px 1px 3px #333;box-shadow:1px 1px 3px #333;font-size:11px!important;font-family:'Lucida Grande','Arial',sans-serif!important;">
+ <table style="border-collapse:collapse;margin:0;padding:0;width:100%;"><tbody><tr>
+ <td style="padding:10px;vertical-align:top;min-width:110px;">
+ <a href="/web/" title="Wayback Machine home page" style="background-color:transparent;border:none;"><img src="/static/images/toolbar/wayback-toolbar-logo.png" alt="Wayback Machine" width="110" height="39" border="0"/></a>
+ </td>
+ <td style="padding:0!important;text-align:center;vertical-align:top;width:100%;">
+
+ <table style="border-collapse:collapse;margin:0 auto;padding:0;width:570px;"><tbody><tr>
+ <td style="padding:3px 0;" colspan="2">
+ <form target="_top" method="get" action="/web/form-submit.jsp" name="wmtb" id="wmtb" style="margin:0!important;padding:0!important;"><input type="text" name="url" id="wmtbURL" value="http://www.open-content.net/specs/draft-jchapweske-thex-02.html" style="width:400px;font-size:11px;font-family:'Lucida Grande','Arial',sans-serif;" onfocus="javascript:this.focus();this.select();" /><input type="hidden" name="type" value="replay" /><input type="hidden" name="date" value="20080316033726" /><input type="submit" value="Go" style="font-size:11px;font-family:'Lucida Grande','Arial',sans-serif;margin-left:5px;width: inherit !important" /><span id="wm_tb_options" style="display:block;"></span></form>
+ </td>
+ <td style="vertical-align:bottom;padding:5px 0 0 0!important;" rowspan="2">
+ <table style="border-collapse:collapse;width:110px;color:#99a;font-family:'Helvetica','Lucida Grande','Arial',sans-serif;"><tbody>
+
+ <!-- NEXT/PREV MONTH NAV AND MONTH INDICATOR -->
+ <tr style="width:110px;height:16px;font-size:10px!important;">
+ <td style="padding-right:9px;font-size:11px!important;font-weight:bold;text-transform:uppercase;text-align:right;white-space:nowrap;overflow:visible;" nowrap="nowrap">
+
+ <a href="/web/20080214024543/http://open-content.net/specs/draft-jchapweske-thex-02.html" style="text-decoration:none;color:#33f;font-weight:bold;background-color:transparent;border:none;" title="14 feb 2008"><strong>FEB</strong></a>
+
+ </td>
+ <td id="displayMonthEl" style="background:#000;color:#ff0;font-size:11px!important;font-weight:bold;text-transform:uppercase;width:34px;height:15px;padding-top:1px;text-align:center;" title="You are here: 3:37:26 mar 16, 2008">MAR</td>
+ <td style="padding-left:9px;font-size:11px!important;font-weight:bold;text-transform:uppercase;white-space:nowrap;overflow:visible;" nowrap="nowrap">
+
+ <a href="/web/20080517043137/http://open-content.net/specs/draft-jchapweske-thex-02.html" style="text-decoration:none;color:#33f;font-weight:bold;background-color:transparent;border:none;" title="17 maj 2008"><strong>MAJ</strong></a>
+
+ </td>
+ </tr>
+
+ <!-- NEXT/PREV CAPTURE NAV AND DAY OF MONTH INDICATOR -->
+ <tr>
+ <td style="padding-right:9px;white-space:nowrap;overflow:visible;text-align:right!important;vertical-align:middle!important;" nowrap="nowrap">
+
+ <a href="/web/20080302051813/http://open-content.net/specs/draft-jchapweske-thex-02.html" title="5:18:13 mar 2, 2008" style="background-color:transparent;border:none;"><img src="/static/images/toolbar/wm_tb_prv_on.png" alt="Previous capture" width="14" height="16" border="0" /></a>
+
+ </td>
+ <td id="displayDayEl" style="background:#000;color:#ff0;width:34px;height:24px;padding:2px 0 0 0;text-align:center;font-size:24px;font-weight: bold;" title="You are here: 3:37:26 mar 16, 2008">16</td>
+ <td style="padding-left:9px;white-space:nowrap;overflow:visible;text-align:left!important;vertical-align:middle!important;" nowrap="nowrap">
+
+ <a href="/web/20080517043137/http://open-content.net/specs/draft-jchapweske-thex-02.html" title="4:31:37 maj 17, 2008" style="background-color:transparent;border:none;"><img src="/static/images/toolbar/wm_tb_nxt_on.png" alt="Next capture" width="14" height="16" border="0"/></a>
+
+ </td>
+ </tr>
+
+ <!-- NEXT/PREV YEAR NAV AND YEAR INDICATOR -->
+ <tr style="width:110px;height:13px;font-size:9px!important;">
+ <td style="padding-right:9px;font-size:11px!important;font-weight: bold;text-align:right;white-space:nowrap;overflow:visible;" nowrap="nowrap">
+
+ <a href="/web/20070310031709/http://www.open-content.net/specs/draft-jchapweske-thex-02.html" style="text-decoration:none;color:#33f;font-weight:bold;background-color:transparent;border:none;" title="10 mar 2007"><strong>2007</strong></a>
+
+ </td>
+ <td id="displayYearEl" style="background:#000;color:#ff0;font-size:11px!important;font-weight: bold;padding-top:1px;width:34px;height:13px;text-align:center;" title="You are here: 3:37:26 mar 16, 2008">2008</td>
+ <td style="padding-left:9px;font-size:11px!important;font-weight: bold;white-space:nowrap;overflow:visible;" nowrap="nowrap">
+
+ <a href="/web/20090415152844/http://www.open-content.net/specs/draft-jchapweske-thex-02.html" style="text-decoration:none;color:#33f;font-weight:bold;background-color:transparent;border:none;" title="15 apr 2009"><strong>2009</strong></a>
+
+ </td>
+ </tr>
+ </tbody></table>
+ </td>
+
+ </tr>
+ <tr>
+ <td style="vertical-align:middle;padding:0!important;">
+ <a href="/web/20080316033726*/http://www.open-content.net/specs/draft-jchapweske-thex-02.html" style="color:#33f;font-size:11px;font-weight:bold;background-color:transparent;border:none;" title="See a list of every capture for this URL"><strong>99 captures</strong></a>
+ <div class="__wb_banner_div" style="margin:0!important;padding:0!important;color:#666;font-size:9px;padding-top:2px!important;white-space:nowrap;" title="Timespan for captures of this URL">13 apr 03 - 28 jun 13</div>
+ </td>
+ <td style="padding:0!important;">
+ <a style="position:relative; white-space:nowrap; width:475px;height:27px;" href="" id="wm-graph-anchor">
+ <div class="__wb_banner_div" id="wm-ipp-sparkline" style="position:relative; white-space:nowrap; width:475px;height:27px;background-color:#fff;cursor:pointer;border-right:1px solid #ccc;" title="Explore captures for this URL">
+ <img id="sparklineImgId" style="position:absolute; z-index:9012; top:0px; left:0px;"
+ onmouseover="showTrackers('inline');"
+ onmouseout="showTrackers('none');"
+ onmousemove="trackMouseMove(event,this)"
+ alt="sparklines"
+ width="475"
+ height="27"
+ border="0"
+ src="/web/jsp/graph.jsp?graphdata=475_27_1996:-1:000000000000_1997:-1:000000000000_1998:-1:000000000000_1999:-1:000000000000_2000:-1:000000000000_2001:-1:000000000000_2002:-1:000000000000_2003:-1:000101000101_2004:-1:010100011201_2005:-1:222102141122_2006:-1:310301140001_2007:-1:023021303311_2008:2:112010001102_2009:-1:111110010001_2010:-1:000000000000_2011:-1:000000202020_2012:-1:110100100010_2013:-1:003302000000_2014:-1:000000000000"></img>
+ <img id="wbMouseTrackYearImg"
+ style="display:none; position:absolute; z-index:9010;"
+ width="25"
+ height="27"
+ border="0"
+ src="/static/images/toolbar/transp-yellow-pixel.png"></img>
+ <img id="wbMouseTrackMonthImg"
+ style="display:none; position:absolute; z-index:9011; "
+ width="2"
+ height="27"
+ border="0"
+ src="/static/images/toolbar/transp-red-pixel.png"></img>
+ </div>
+ </a>
+
+ </td>
+ </tr></tbody></table>
+ </td>
+ <td style="text-align:right;padding:5px;width:65px;font-size:11px!important;">
+ <a href="javascript:;" onclick="document.getElementById('wm-ipp').style.display='none';" style="display:block;padding-right:18px;background:url(/static/images/toolbar/wm_tb_close.png) no-repeat 100% 0;color:#33f;font-family:'Lucida Grande','Arial',sans-serif;margin-bottom:23px;background-color:transparent;border:none;" title="Close the toolbar">Close</a>
+ <a href="http://faq.web.archive.org/" style="display:block;padding-right:18px;background:url(/static/images/toolbar/wm_tb_help.png) no-repeat 100% 0;color:#33f;font-family:'Lucida Grande','Arial',sans-serif;background-color:transparent;border:none;" title="Get some help using the Wayback Machine">Help</a>
+ </td>
+ </tr></tbody></table>
+
+</div>
+</div>
+<script type="text/javascript">
+ var wmDisclaimBanner = document.getElementById("wm-ipp");
+ if(wmDisclaimBanner != null) {
+ disclaimElement(wmDisclaimBanner);
+ }
+</script>
+<!-- END WAYBACK TOOLBAR INSERT -->
+
+<table border="0" cellpadding="0" cellspacing="2" width="30" height="15" align="right"><tr><td bgcolor="#990000" align="center" width="30" height="15"><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#toc" CLASS="link2"><font face="monaco, MS Sans Serif" color="#ffffff" size="1"><b> TOC </b></font></a><br></td></tr></table>
+<table width="66%" border="0" cellpadding="0" cellspacing="0"><tr><td><table width="100%" border="0" cellpadding="2" cellspacing="1">
+<tr valign="top"><td width="33%" bgcolor="#666666" class="header"> </td><td width="33%" bgcolor="#666666" class="header">J. Chapweske</td></tr>
+<tr valign="top"><td width="33%" bgcolor="#666666" class="header"> </td><td width="33%" bgcolor="#666666" class="header">Onion Networks, Inc.</td></tr>
+<tr valign="top"><td width="33%" bgcolor="#666666" class="header"> </td><td width="33%" bgcolor="#666666" class="header">G. Mohr</td></tr>
+<tr valign="top"><td width="33%" bgcolor="#666666" class="header"> </td><td width="33%" bgcolor="#666666" class="header">Bitzi, Inc.</td></tr>
+<tr valign="top"><td width="33%" bgcolor="#666666" class="header"> </td><td width="33%" bgcolor="#666666" class="header">March 4, 2003</td></tr>
+</table></td></tr></table>
+<div align="right"><font face="monaco, MS Sans Serif" color="#990000" size="+3"><b><br><span class="title">Tree Hash EXchange format (THEX)</span></b></font></div>
+<font face="verdana, helvetica, arial, sans-serif" size="2">
+
+<h3>Abstract</h3>
+
+<p>
+This memo presents the Tree Hash Exchange (THEX) format, for
+exchanging Merkle Hash Trees built up from the subrange hashes of discrete
+digital files. Such tree hash data structures assist in file integrity
+verification, allowing arbitrary subranges of bytes to be verified before the
+entire file has been received.
+</p>
+<a name="toc"><br><hr size="1" shade="0"></a>
+<table border="0" cellpadding="0" cellspacing="2" width="30" height="15" align="right"><tr><td bgcolor="#990000" align="center" width="30" height="15"><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#toc" CLASS="link2"><font face="monaco, MS Sans Serif" color="#ffffff" size="1"><b> TOC </b></font></a><br></td></tr></table>
+<h3>Table of Contents</h3>
+<ul compact class="toc">
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor1">1.</a>
+Introduction<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor2">2.</a>
+Merkle Hash Trees<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor3">2.1</a>
+Hash Functions<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor4">2.2</a>
+Unbalanced Trees<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#choice_of_segment_size">2.3</a>
+Choice Of Segment Size<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor5">3.</a>
+Serialization Format<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor6">3.1</a>
+DIME Encapsulation<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor7">3.2</a>
+XML Tree Description<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor8">3.2.1</a>
+File Size<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor9">3.2.2</a>
+File Segment Size<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor10">3.2.3</a>
+Digest Algorithm<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor11">3.2.4</a>
+Digest Output Size<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor12">3.2.5</a>
+Serialized Tree Depth<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor13">3.2.6</a>
+Serialized Tree Type<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor14">3.2.7</a>
+Serialized Tree URI<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor15">3.3</a>
+Breadth-First Serialization<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor16">3.3.1</a>
+Serialization Type URI<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#rfc.authors">§</a>
+Authors' Addresses<br></b>
+<b><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#anchor17">A.</a>
+Test Vectors<br></b>
+</ul>
+<br clear="all">
+
+<a name="anchor1"><br><hr size="1" shade="0"></a>
+<table border="0" cellpadding="0" cellspacing="2" width="30" height="15" align="right"><tr><td bgcolor="#990000" align="center" width="30" height="15"><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#toc" CLASS="link2"><font face="monaco, MS Sans Serif" color="#ffffff" size="1"><b> TOC </b></font></a><br></td></tr></table>
+<a name="rfc.section.1"></a><h3>1. Introduction</h3>
+
+<p>
+The Merkle Hash Tree, invented by Ralph Merkle, is a hash construct that
+exhibits desirable properties for verifying the integrity of files and file subranges
+in an incremental or out-of-order fashion. This document describes a binary
+serialization format for hash trees that is compact and optimized for both
+sequential and random access.
+This memo has two goals:
+
+<ol class="text">
+
+<li>
+To describe Merkle Hash Trees and how they are used for file integrity
+verification.
+</li>
+
+<li>
+To describe a serialization format for storage and transmission of hash
+trees.
+</li>
+
+</ol>
+<p>
+
+</p>
+
+<a name="anchor2"><br><hr size="1" shade="0"></a>
+<table border="0" cellpadding="0" cellspacing="2" width="30" height="15" align="right"><tr><td bgcolor="#990000" align="center" width="30" height="15"><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#toc" CLASS="link2"><font face="monaco, MS Sans Serif" color="#ffffff" size="1"><b> TOC </b></font></a><br></td></tr></table>
+<a name="rfc.section.2"></a><h3>2. Merkle Hash Trees</h3>
+
+<p>
+
+It is common practice in distributed systems to use secure hash algorithms to
+verify the integrity of content. The employment of secure hash algorithms
+enables systems to retreive content from completely untrusted hosts with only
+a small amount of trusted metadata.
+
+</p>
+
+<p>
+
+Typically, algorithms such as SHA-1 and MD5 have been used to check the content
+integrity after retrieving the entire file. These full file hash techniques
+work fine in an environment where the content is received from a single host
+and there are no streaming requirements. However, there are an increasing
+number of systems that retrieve a single piece of content from multiple
+untrusted hosts, and require content verification well in advance of retrieving
+the entire file.
+
+</p>
+
+<p>
+
+Many modern peer-to-peer content delivery systems employ fixed size "block
+hashes" to provide a finer level of granularity in their integrity checking.
+This approach is still limited in the verification resolution it can attain.
+Additionally, all of the hash information must be retrieved from a trusted host,
+which can limit the scalability and reliability of the system.
+
+</p>
+
+<p>
+
+Another way to verify content is to use the hash tree approach. This approach
+has the desired characteristics missing from the full file hash approach and
+works well for very large files. The idea is to break the file up into a number
+of small pieces, hash those pieces, and then iteratively combine and rehash the
+resulting hashes in a tree-like fashion until a single "root hash" is created.
+
+</p>
+
+<p>
+
+The root hash by itself behaves exactly the same way that full file hashes do.
+If the root hash is retrieved from a trusted source, it can be used to verify
+the integrity of the entire content. More importantly, the root hash can be
+combined with a small number of other hashes to verify the integrity of any of
+the file segments.
+
+<p>
+
+For example, consider a file made up of four segments,
+S1, S2, S3, and S4. Let H() be the hash function, and '+'
+indicate concatenation. You could take the traditional
+hash value:
+
+</p>
+</font><pre>
+ VALUE=H(S1+S2+S3+S4)
+</pre><font face="verdana, helvetica, arial, sans-serif" size="2">
+
+<p>
+
+Or, you could employ a tree approach. The tree hash utilizes two hash algorithms - one for leaf hashes and one for internal hashes. Let LH() be the leaf hash function and IH() be the internal hash function:
+
+</p>
+</font><pre>
+
+ ROOT=IH(E+F)
+ / \
+ / \
+ E=IH(A+B) F=IH(C+D)
+ / \ / \
+ / \ / \
+ A=LH(S1) B=LH(S2) C=LH(S3) D=LH(S4)
+
+</pre><font face="verdana, helvetica, arial, sans-serif" size="2">
+
+<p>
+
+Now, assuming that the ROOT is retrieved from a trusted source, the integrity
+of a file segment coming from an untrusted source can be checked with a small
+amount of hash data. For instance, if S1 is received from an untrusted host,
+the integrity of S1 can be verified with just B and F.
+
+With these, it can be verified that, yes: S1 can be combined up to
+equal the ROOT hash, even without seeing the other
+segments. (It is just as impractical to create falsified values
+of B and F as it is to manipulate any good hash function to
+give desired results -- so B and F can come from untrusted sources
+as well.)
+
+Similarly, if some other untrusted source provides segments
+S3 and S4, their integrity can be easily checked when combined with hash E.
+From segments S3 and S4, the values of C and D and then F can be calculated.
+
+With these, you can verify that S3 and S4 can combine up
+to create the ROOT -- even if other sources are providing bogus S1 and S2
+segments. Bad info can be immediately recognized and discarded, and
+good info retained, even in situations where you could not even begin
+to calculate a traditional full-file hash.
+
+</p>
+
+</p>
+
+<p>
+
+Another interesting property of the tree approach is that it can be used to
+verify (tree-aligned) subranges whose size is any multiple of the base segment
+size.
+
+</p>
+
+<p>
+Consider for example an initial segment size of 1,024 bytes, and
+a file of 32GB. You could verify a single 1,024-byte block, with
+about 25 proof-assist values, or a block of size 16GB, with a single
+proof-assist value -- or anything in between.
+
+</p>
+
+<a name="rfc.section.2.1"></a><h4><a name="anchor3">2.1</a> Hash Functions</h4>
+
+<p>
+
+The strength of the hash tree construct is only as strong as the underlying hash algorithm. Thus, it is RECOMMENDED that a secure hash algorithm such as SHA-1 be used as the basis of the hash tree.
+
+</p>
+
+<p>
+
+In order to protect against collisions between leaf hashes and internal hashes, different hash constructs are used to hash the leaf nodes and the internal nodes. The same hash algorithm is used as the basis of each construct, but a single '1' byte in network byte order, or 0x01 is prepended to the input of the internal node hashes, and a single '0' byte, or 0x00 is prepended to the input of the leaf node hashes.
+
+</p>
+
+<p>
+
+<p>
+
+Let H() be the secure hash algorithm, for example SHA-1.
+
+</p>
+</font><pre>
+internal hash function = IH(X) = H(0x01, X)
+
+leaf hash function = LH(X) = H(0x00, X)
+</pre><font face="verdana, helvetica, arial, sans-serif" size="2">
+
+</p>
+
+<a name="rfc.section.2.2"></a><h4><a name="anchor4">2.2</a> Unbalanced Trees</h4>
+
+<p>
+
+For trees that are unbalanced -- that is, they have a number of leaves which
+is not a power of 2 -- interim hash values which do not have a sibling value
+to which they may be concatenated are promoted, unchanged, up the tree until
+a sibling is found.
+
+<p>
+
+For example, consider a file made up of 5 segments, S1, S2, S3, S4, and S5.
+
+</p>
+</font><pre>
+ ROOT=IH(H+E)
+ / \
+ / \
+ H=IH(F+G) E
+ / \ \
+ / \ \
+ F=IH(A+B) G=IH(C+D) E
+ / \ / \ \
+ / \ / \ \
+ A=LH(S1) B=LH(S2) C=LH(S3) D=LH(S4) E=LH(S5)
+
+</pre><font face="verdana, helvetica, arial, sans-serif" size="2">
+
+<p>
+
+In the above example, E does not have any immediate siblings with which
+to be combined to calculate the next generation. So, E is promoted up
+the tree, without being rehashed, until it can be paired with value H.
+The values H and E are then concatenated, and hashed, to produce the
+ROOT hash.
+
+</p>
+
+</p>
+
+<a name="rfc.section.2.3"></a><h4><a name="choice_of_segment_size">2.3</a> Choice Of Segment Size</h4>
+
+<p>
+ Any segment size is possible, but the choice of base segment
+size establishes the smallest possible unit of verification.
+</p>
+
+<p>
+If the the segment size is equal to or larger than the file to be hashed, the
+tree hash value is the value of the single segment's value, which is
+the same as the underlying hash algorithm value for the whole file.
+</p>
+
+<p>
+A segment size equal to the digest algorithm output size would
+more than double the total amount of data to be hashed, and thus more
+than double the time required to calculate the tree hash structure, as
+compared to a simple full-file hash. However, once the segment size
+reaches several multiples of the digest size, calculating the tree
+adds only a small fractional time overhead beyond what a traditional
+full-file hash would cost.
+
+</p>
+
+<p>
+Otherwise, smaller segments are better. Smaller segments allow, but
+do not require, the retention and use of fine-grained verification info,
+(A stack-based tree calculation procedure need never retain more
+than one pending internal node value per generation before it can be
+combined with a sibling, and all interim values below a certain
+generation size of interest can be discarded.) Further, it is
+beneficial for multiple application domains and even files of wildly
+different sizes to share the same base segment size, so that tree
+structures can be shared and used to discover correlated subranges.
+
+</p>
+
+<p>
+Thus the authors recommend a segment size of 1,024 bytes for most
+applications, as a sort of "smallest common denominator", even for
+applications involving multi-gigabyte or terabyte files. This segment
+size is 40-50 times larger than common secure hash digest lengths
+(20-24 bytes), and thus adds no more than 5-10% in running time as
+compared to the "infinite segment" size case -- the traditional
+full-file hash.
+
+</p>
+
+<p>
+Considering a 1 terabyte file, the maximum dynamic
+state required during the calculation of the tree root value is
+29 interim node values -- less than 1KB assuming a 20-byte digest
+algorithm like SHA-1. Only interim values in generations of
+interest for range verification need to be remembered for tree
+exchange, so if only 8GB ranges ever need to be verified, all
+but the top 8 generations of internal values (255 hashes) can
+be discarded.
+
+</p>
+
+<a name="anchor5"><br><hr size="1" shade="0"></a>
+<table border="0" cellpadding="0" cellspacing="2" width="30" height="15" align="right"><tr><td bgcolor="#990000" align="center" width="30" height="15"><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#toc" CLASS="link2"><font face="monaco, MS Sans Serif" color="#ffffff" size="1"><b> TOC </b></font></a><br></td></tr></table>
+<a name="rfc.section.3"></a><h3>3. Serialization Format</h3>
+
+<p>
+
+This section presents a serialization format for Merkle Hash Trees that utilizes the Direct Internet Message Encapsulation (DIME) format. DIME is a generic message format that allows for multiple payloads, either text or binary. The Merkle Hash Tree serialization format consists of two different payloads. The first is XML encoded meta-data about the hash tree, and the second is binary serialization of the tree itself. The binary serialization is required for two important reasons:
+
+<ol class="text">
+
+<li>
+
+Compactness of Representation - A key virtue of the hash tree approach is that it provides considerable integrity checking power with a relatively small amount of data. A typical hash tree consists of a large number of small hashes. Thus a text encoding, such as XML, could easily double the storage and transmission requirements of the hash tree, negating one of its key benefits.
+
+</li>
+
+<li>
+
+Random Access - In order to take full advantage of the hash tree construct, it is often necessary to read the elements of the hash tree in a random access fashion. A common usage of this serialization format will be to access hash data over the HTTP protocol using "Range Requests". This will allow implementors to retrieve small bits of hash information on-demand, even requesting different parts of the tree from different hosts on the network.
+
+</li>
+
+</ol>
+<p>
+
+</p>
+
+<a name="rfc.section.3.1"></a><h4><a name="anchor6">3.1</a> DIME Encapsulation</h4>
+
+<p>
+
+It is RECOMMENDED that DIME be used to encapsulate the payloads described in this specification. The current version of DIME is "draft-nielsen-dime-01" at (http://gotdotnet.com/team/xml_wsspecs/dime/default.aspx).
+
+</p>
+
+<p>
+
+It is RECOMMENDED that the first payload in the DIME Message be the XML
+Tree Description. The XML Tree description payload MUST be before the the
+binary serialized tree.
+
+</p>
+
+<p>
+
+It is RECOMMENDED that the binary serialized tree be stored in a single
+payload rather than using chunked payloads. This will allow implementations
+to read the tree hash data in a random access fashion within the payload.
+
+</p>
+
+<a name="rfc.section.3.2"></a><h4><a name="anchor7">3.2</a> XML Tree Description</h4>
+
+<p>
+
+The XML Tree Description contains metadata about the hash tree and file that is
+necessary to interpret the binary serialized tree. An important consideration in the design of THEX is the intention for it to be received from untrusted sources within a distributed network. The only information that needs to be obtained from a trusted source is the root hash and the segment size. The root hash by itself can be used to verify the integrity of the serialized tree and of the file itself.
+
+</p>
+
+<p>
+
+It is RECOMMENDED that implementers assume that the serialized file was obtained from an untrusted source, thus the use of this format to store non-verifiable information, such as general file metadata, is highly discouraged. For instance, a malicious party could easily forge metadata, such as the author or file name.
+
+</p>
+
+<p>
+</font><pre>
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE hashtree system "http://open-content.net/spec/thex/thex.dtd">
+<hashtree>
+ <file size='1146045066' segmentsize='1024'/>
+ <digest algorithm='http://www.w3.org/2000/09/xmldsig#sha1'
+ outputsize='20'/>
+ <serializedtree depth='22'
+ type='http://open-content.net/spec/thex/breadthfirst'
+ uri='uuid:09233523-345b-4351-b623-5dsf35sgs5d6'/>
+</hashtree>
+</pre><font face="verdana, helvetica, arial, sans-serif" size="2">
+
+</p>
+
+<a name="rfc.section.3.2.1"></a><h4><a name="anchor8">3.2.1</a> File Size</h4>
+
+<p>
+
+The file size attribute refers to the size, in bytes, of the file that the
+hash tree was generated from.
+
+</p>
+
+<a name="rfc.section.3.2.2"></a><h4><a name="anchor9">3.2.2</a> File Segment Size</h4>
+
+<p>
+
+The file segment size identifies the size, in bytes, of the file segments that were used to create the hash tree. As noted in <a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#choice_of_segment_size">Choice Of Segment Size</a>, it is recommended that applications use a small, common segment size such as 1,024 bytes in order to retain maximum flexibility and interoperability.
+
+</p>
+
+<a name="rfc.section.3.2.3"></a><h4><a name="anchor10">3.2.3</a> Digest Algorithm</h4>
+
+<p>
+
+This attribute provides the identifier URI for the digest algorithm. A URI is used here as an identifier instead of a regular string to avoid the overhead of IANA-style registration. By using URIs, new types can be created without having to consult any other entity. The URIs are only to be used for type identification purposes, but it is RECOMMENDED that the URIs point to information about the given digest function. This convention is inspired by RFC 3275, the XML Signature Specification.
+For instance, the SHA-1 algorithm is identified by "http://www.w3.org/2000/09/xmldsig#sha1". All digest algorithms defined in RFC 3275 are supported. The Tiger algorithm is also supported and is identified by "http://open-content.net/spec/digest/tiger".
+
+</p>
+
+<a name="rfc.section.3.2.4"></a><h4><a name="anchor11">3.2.4</a> Digest Output Size</h4>
+
+<p>
+
+This attribute specifies the size of the output of the hash function, in bytes.
+
+</p>
+
+<a name="rfc.section.3.2.5"></a><h4><a name="anchor12">3.2.5</a> Serialized Tree Depth</h4>
+
+<p>
+
+This attribute specifies the number of levels of the tree that have been serialized. This value allows control over the amount of storage space required by the serialized tree. In general, each row added to the tree will double the storage requirements while also doubling the verification resolution.
+
+</p>
+
+<a name="rfc.section.3.2.6"></a><h4><a name="anchor13">3.2.6</a> Serialized Tree Type</h4>
+
+<p>
+
+This attribute provides the identifier URI for the serialization type. Just as with the Digest Algorithm, new serialization types can be added and described without going through a formal IANA-style process. One serialization type is defined for "Breadth-First Serialization" later in this document.
+
+</p>
+
+<a name="rfc.section.3.2.7"></a><h4><a name="anchor14">3.2.7</a> Serialized Tree URI</h4>
+
+<p>
+
+This attribute provides the URI of the binary serialized tree payload. If used within a DIME payload, it is recommended that this URI be location independant, such as the "uuid:" URI's used in the SOAP in DIME specification or SHA-1 URNs.
+
+</p>
+
+<a name="rfc.section.3.3"></a><h4><a name="anchor15">3.3</a> Breadth-First Serialization</h4>
+
+<p>
+
+Normal breadth-first serialization is the recommended manner in which to serialize the hash tree. This format includes the root hash first, and then each "row" of hashes is serialized until the tree has been serialized to the lowest level as specified by the "Serialized Tree Depth" field.
+
+<p>
+
+For example, consider a file made up of 5 segments, S1, S2, S3, S4, and S5.
+
+</p>
+</font><pre>
+ ROOT=IH(H+E)
+ / \
+ / \
+ H=IH(F+G) E
+ / \ \
+ / \ \
+ F=IH(A+B) G=IH(C+D) E
+ / \ / \ \
+ / \ / \ \
+ A=LH(S1) B=LH(S2) C=LH(S3) D=LH(S4) E=LH(S5)
+</pre><font face="verdana, helvetica, arial, sans-serif" size="2">
+
+<p>
+
+The hashes would be serialized in the following order: ROOT, H, E, F, G, E, A, B, C, D, E. Notice that E is serialized as a part of the each row. This is due to its promotion as there are no available siblings in the lower rows. If we choose to serialize the entire tree, the serialized tree depth would be 4, and for a 20 byte digest output, the entire tree payload would occupy 11*20 = 220 bytes.
+
+</p>
+
+</p>
+
+<a name="rfc.section.3.3.1"></a><h4><a name="anchor16">3.3.1</a> Serialization Type URI</h4>
+
+<p>
+
+The serialization type URI for a Merkle Hash Tree serialized in normal breadth-first form is "http://open-content.net/spec/thex/breadthfirst".
+
+</p>
+
+<a name="rfc.authors"><br><hr size="1" shade="0"></a>
+<table border="0" cellpadding="0" cellspacing="2" width="30" height="15" align="right"><tr><td bgcolor="#990000" align="center" width="30" height="15"><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#toc" CLASS="link2"><font face="monaco, MS Sans Serif" color="#ffffff" size="1"><b> TOC </b></font></a><br></td></tr></table>
+<h3>Authors' Addresses</h3>
+<table width="99%" border="0" cellpadding="0" cellspacing="0">
+<tr><td class="author-text"> </td>
+<td class="author-text">Justin Chapweske</td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text">Onion Networks, Inc.</td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text">1668 Rosehill Circle</td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text">Lauderdale, MN 55108</td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text">US</td></tr>
+<tr><td class="author" align="right">EMail: </td>
+<td class="author-text"><a href="mailto:ju...@on...">ju...@on...</a></td></tr>
+<tr><td class="author" align="right">URI: </td>
+<td class="author-text"><a href="/web/20080316033726/http://onionnetworks.com/">http://onionnetworks.com/</a></td></tr>
+<tr cellpadding="3"><td> </td><td> </td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text">Gordon Mohr</td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text">Bitzi, Inc.</td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text"></td></tr>
+<tr><td class="author-text"> </td>
+<td class="author-text"></td></tr>
+<tr><td class="author" align="right">EMail: </td>
+<td class="author-text"><a href="mailto:go...@bi...">go...@bi...</a></td></tr>
+<tr><td class="author" align="right">URI: </td>
+<td class="author-text"><a href="/web/20080316033726/http://bitzi.com/">http://bitzi.com/</a></td></tr>
+</table>
+
+<a name="anchor17"><br><hr size="1" shade="0"></a>
+<table border="0" cellpadding="0" cellspacing="2" width="30" height="15" align="right"><tr><td bgcolor="#990000" align="center" width="30" height="15"><a href="/web/20080316033726/http://www.open-content.net/specs/draft-jchapweske-thex-02.html#toc" CLASS="link2"><font face="monaco, MS Sans Serif" color="#ffffff" size="1"><b> TOC </b></font></a><br></td></tr></table>
+<a name="rfc.section.A"></a><h3>Appendix A. Test Vectors</h3>
+
+<p>
+
+The following are test vectors for producing THEX hash trees using the Tiger hash algorithm. The 'urn:sha1' entries specify the full file SHA-1 of the data, while the 'urn:tree:tiger' entries specify the root of the THEX hash tree of the data.
+</font><pre>
+The empty (zero-length) file:
+
+ urn:sha1:3I42H3S6NNFQ2MSVX7XZKYAYSCX5QBYJ
+ urn:tree:tiger:LWPNACQDBZRYXW3VHJVCJ64QBZNGHOHHHZWCLNQ
+
+A file with a single zero byte:
+
+ urn:sha1:LOUTZHNQZ74T6UVVEHLUEDSD63W2E6CP
+ urn:tree:tiger:VK54ZIEEVTWNAUI5D5RDFIL37LX2IQNSTAXFKSA
+
+A file with 1024 'A' characters:
+
+ urn:sha1:ORWD6TJINRJR4BS6RL3W4CWAQ2EDDRVU
+ urn:tree:tiger:L66Q4YVNAFWVS23X2HJIRA5ZJ7WXR3F26RSASFA
+
+A file with 1025 'A' characters:
+
+ urn:sha1:UUHHSQPHQXN5X6EMYK6CD7IJ7BHZTE77
+ urn:tree:tiger:PZMRYHGY6LTBEH63ZWAHDORHSYTLO4LEFUIKHWY
+</pre><font face="verdana, helvetica, arial, sans-serif" size="2">
+
+</p>
+</font></body></html>
+
+
+
+
+
+<!--
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+
+ ALL OTHER CONTENT MAY ALSO BE PROTECTED BY COPYRIGHT (17 U.S.C.
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+-->
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+<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
+<!Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) by Nikos Drakos (ni...@cb...), CBLU, University of Leeds >
+<HEAD>
+<TITLE> Motivation and Design Requirements</TITLE>
+</HEAD>
+<BODY>
+<meta name="description" value=" Motivation and Design Requirements">
+<meta name="keywords" value="tiger">
+<meta name="resource-type" value="document">
+<meta name="distribution" value="global">
+<P>
+ <BR> <HR><A NAME=tex2html20 HREF="node2.html"><IMG ALIGN=BOTTOM ALT="next" SRC="http://cbl.leeds.ac.uk/nikos/figs//next_motif.gif"></A> <A NAME=tex2html18 HREF="tiger.html"><IMG ALIGN=BOTTOM ALT="up" SRC="http://cbl.leeds.ac.uk/nikos/figs//up_motif.gif"></A> <A NAME=tex2html12 HREF="tiger.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="http://cbl.leeds.ac.uk/nikos/figs//previous_motif.gif"></A> <BR>
+<B> Next:</B> <A NAME=tex2html21 HREF="node2.html"> Our Proposal</A>
+<B>Up:</B> <A NAME=tex2html19 HREF="tiger.html">Tiger: A Fast New </A>
+<B> Previous:</B> <A NAME=tex2html13 HREF="tiger.html">Tiger: A Fast New </A>
+<BR> <HR> <P>
+<H1><A NAME=SECTION00010000000000000000> Motivation and Design Requirements</A></H1>
+<P>
+Cryptographic hash functions are very important for cryptographic protocols.
+When used with signature schemes, their role is to reduce the amount of data
+which must be signed [Pre93] and to break up any properties such as
+multiplicative homomorphism which might be exploited by an opponent [And93]. In
+short, they need to be both efficient and secure; and in most commercial
+applications, they need to run quickly in software on all the common hardware
+platforms.
+<P>
+Some hash functions are based on feedforward modes of block ciphers [Pre93],
+but the main contenders have been the functions based on MD4 [Riv90], which
+include MD5 [Riv92], RIPE-MD [RACE95], SHA [NIST92] and SHA-1 [NIST95]. Another
+family was Snefru, and its derivative Snefru-8 [Mer90].
+<P>
+However, collisions for Snefru were found in 1990 [BS91] [BS93], and recently a
+collision of MD4 has also been found [Dob95]. These attacks cast doubt on the
+security of the other members of these families. One may only speculate at how
+long each function will remain unbroken; however it seems prudent to start work
+now on replacements.
+<P>
+From the performance point of view, all the functions mentioned above were
+designed for 32-bit processors. The next generation of processors has 64-bit
+words, and includes the DEC Alpha series as well as forthcoming processors from
+Intel, HP and IBM. It seems reasonable to assume that, with the exception of
+microcontrollers used in embedded applications, the majority of systems will
+use 64-bit processors within five years or so. However, on such processors, the
+above families of hash functions cannot be implemented efficiently.
+<P>
+For example, the MD family uses many 32-bit rotations and additions, so a
+64-bit register can only handle one 32-bit value at a time, which decreases the
+potential speed by a factor of about two. Moreover, the Alpha architecture does
+not have any rotation operations, whether 64-bit or 32-bit.
+<P>
+From these considerations, we believe that a next generation hash function:
+<P>
+<UL><LI> should be secure. At the very least it must be one-way, collision-free
+and multiplication-free;
+<P>
+<LI> should run quickly on 64-bit processors, and yet not run too slowly on
+the already fielded 32-bit machines such as Intel's 80486;
+<P>
+<LI> should, insofar as possible, be usable as a drop-in replacement for MD4,
+MD5, SHA and SHA-1.
+</UL><BR> <HR><A NAME=tex2html20 HREF="node2.html"><IMG ALIGN=BOTTOM ALT="next" SRC="http://cbl.leeds.ac.uk/nikos/figs//next_motif.gif"></A> <A NAME=tex2html18 HREF="tiger.html"><IMG ALIGN=BOTTOM ALT="up" SRC="http://cbl.leeds.ac.uk/nikos/figs//up_motif.gif"></A> <A NAME=tex2html12 HREF="tiger.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="http://cbl.leeds.ac.uk/nikos/figs//previous_motif.gif"></A> <BR>
+<B> Next:</B> <A NAME=tex2html21 HREF="node2.html"> Our Proposal</A>
+<B>Up:</B> <A NAME=tex2html19 HREF="tiger.html">Tiger: A Fast New </A>
+<B> Previous:</B> <A NAME=tex2html13 HREF="tiger.html">Tiger: A Fast New </A>
+<BR> <HR> <P>
+<BR> <HR>
+<P><ADDRESS>
+<I>Eli Biham <BR>
+Thu Feb 8 15:00:23 IST 1996</I>
+</ADDRESS>
+</BODY>
Added: trunk/Hashes/Tiger/node2.html
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--- trunk/Hashes/Tiger/node2.html (rev 0)
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+<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
+<!Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) by Nikos Drakos (ni...@cb...), CBLU, University of Leeds >
+<HEAD>
+<TITLE> Our Proposal</TITLE>
+</HEAD>
+<BODY>
+<meta name="description" value=" Our Proposal">
+<meta name="keywords" value="tiger">
+<meta name="resource-type" value="document">
+<meta name="distribution" value="global">
+<P>
+ <BR> <HR><A NAME=tex2html30 HREF="node3.html"><IMG ALIGN=BOTTOM ALT="next" SRC="http://cbl.leeds.ac.uk/nikos/figs//next_motif.gif"></A> <A NAME=tex2html28 HREF="tiger.html"><IMG ALIGN=BOTTOM ALT="up" SRC="http://cbl.leeds.ac.uk/nikos/figs//up_motif.gif"></A> <A NAME=tex2html22 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="http://cbl.leeds.ac.uk/nikos/figs//previous_motif.gif"></A> <BR>
+<B> Next:</B> <A NAME=tex2html31 HREF="node3.html"> Specification</A>
+<B>Up:</B> <A NAME=tex2html29 HREF="tiger.html">Tiger: A Fast New </A>
+<B> Previous:</B> <A NAME=tex2html23 HREF="node1.html"> Motivation and Design </A>
+<BR> <HR> <P>
+<H1><A NAME=SECTION00020000000000000000> Our Proposal</A></H1>
+<P>
+In this paper we propose a new hash function, which is called Tiger, as it is
+strong and fast: as fast as SHA-1 on 32-bit processors, and about three times
+faster on 64-bit (DEC Alpha) processors. It is also expected to be faster than
+SHA-1 on 16-bit processors, since SHA-1 is optimized for 32-bit machines, while
+our proposal is designed to work adequately on many word sizes.
+<P>
+Its main operation is table lookup into four S-boxes, each from eight bits to
+64 bits. On 32-bit machines this can be implemented as a pair of table lookups,
+with the offset computation done only once. The other operations are 64-bit
+additions and subtractions, 64-bit multiplication by small constants (5, 7 and
+9), 64-bit shifts and logical operations such as XOR and NOT. All these
+operations are at most twice as slow on 32-bit machines, with the exception of
+the shifts and the multiplications by small constants which are four or five
+times slower (Alpha processors have special instructions which multiply by
+constants of the form <IMG ALIGN=MIDDLE ALT="" SRC="img1.gif"> and <IMG ALIGN=MIDDLE ALT="" SRC="img2.gif">).
+<P>
+For drop-in compatibility, we adopt the outer structure of the MD4 family: the
+message is padded by a single `1' bit followed by a string of `0's and finally
+the message length as a 64-bit word. The result is divided into <b>n</b> 512-bit
+blocks.
+<P>
+The size of the hash value, and of the intermediate state, is three words, or
+192 bits. This value was chosen for the following reasons:
+<P>
+<OL><LI> Since we use 64-bit words, the size should be a multiple of 64;
+<LI> To be compatible with applications using SHA-1, the hash size should be
+at least 160 bits;
+<LI> All the successful shortcut attacks on existing hash functions attack the
+intermediate state, rather than the final hash value. The attacker typically
+chooses two colliding values for an intermediate block, and this propagates to
+a collision of the full function. However, these attacks would not work if the
+intermediate hash values were larger.
+</OL>
+<P>
+Tiger with the full 192 bits of output in use may be called Tiger/192, and we
+recommend its use in all new applications. When replacing other functions in
+existing applications, we suggest two shorter variants:
+<P>
+<OL><LI> Tiger/160: the hash value is the first 160 bits of the result of
+Tiger/192, and is used for compatibility with SHA and SHA-1;
+<LI> Tiger/128: the hash value is the first 128 bits of the result of
+Tiger/192, and is used for compatibility with MD4, MD5, RIPE-MD, the Snefru
+variants and some hash functions based on block ciphers.
+</OL>
+<P>
+We conjecture that all the three variants of Tiger are collision-free, in that
+collisions for Tiger/<b>N</b> cannot be found with substantially less effort than
+<IMG ALIGN=MIDDLE ALT="" SRC="img3.gif">. We also believe that they are one-way and multiplication-free
+[And93].
+<P>
+The efficiency of this function is partially based on the potential parallelism
+in its design. In the MD and Snefru families, each operation depends directly
+on the result of the previous operation, and thus RISC processors cannot be
+used efficiently due to pipeline stalls. In each round of Tiger, the eight
+table lookup operations can be done in parallel, so compilers can make best use
+of pipelining. The design also allows efficient hardware implementation.
+<P>
+The memory size required by Tiger is only slightly more than the size of the
+four S boxes. If this can be accommodated within the cache of the processor,
+the computation runs about twice as fast (measured on DEC Alpha). The size of
+the four S boxes is <IMG ALIGN=BOTTOM ALT="" SRC="img4.gif"> Kbytes, which is about the size
+of the cache on most machines. If eight S boxes were used, 16 Kbytes would be
+required, which is twice as the size of the cache on Alpha.
+<P>
+<BR> <HR><A NAME=tex2html30 HREF="node3.html"><IMG ALIGN=BOTTOM ALT="next" SRC="http://cbl.leeds.ac.uk/nikos/figs//next_motif.gif"></A> <A NAME=tex2html28 HREF="tiger.html"><IMG ALIGN=BOTTOM ALT="up" SRC="http://cbl.leeds.ac.uk/nikos/figs//up_motif.gif"></A> <A NAME=tex2html22 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="http://cbl.leeds.ac.uk/nikos/figs//previous_motif.gif"></A> <BR>
+<B> Next:</B> <A NAME=tex2html31 HREF="node3.html"> Specification</A>
+<B>Up:</B> <A NAME=tex2html29 HREF="tiger.html">Tiger: A Fast New </A>
+<B> Previous:</B> <A NAME=tex2html23 HREF="node1.html"> Motivation and Design </A>
+<BR> <HR> <P>
+<BR> <HR>
+<P><ADDRESS>
+<I>Eli Biham <BR>
+Thu Feb 8 15:00:23 IST 1996</I>
+</ADDRESS>
+</BODY>
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+<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
+<!Converted with LaTeX2HTML 95.1 (Fri Jan 20 1995) by Nikos Drakos (ni...@cb...), CBLU, University of Leeds >
+<HEAD>
+<TITLE> Specification</TITLE>
+</HEAD>
+<BODY>
+<meta name="description" value=" Specification">
+<meta name="keywords" value="tiger">
+<meta name="resource-type" value="document">
+<meta name="distribution" value="global">
+<P>
+ <BR> <HR><A NAME=tex2html40 HREF="node4.html"><IMG ALIGN=BOTTOM ALT="next" SRC="http://cbl.leeds.ac.uk/nikos/figs//next_motif.gif"></A> <A NAME=tex2html38 HREF="tiger.html"><IMG ALIGN=BOTTOM ALT="up" SRC="http://cbl.leeds.ac.uk/nikos/figs//up_motif.gif"></A> <A NAME=tex2html32 HREF="node2.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="http://cbl.leeds.ac.uk/nikos/figs//previous_motif.gif"></A> <BR>
+<B> Next:</B> <A NAME=tex2html41 HREF="node4.html"> Security</A>
+<B>Up:</B> <A NAME=tex2html39 HREF="tiger.html">Tiger: A Fast New </A>
+<B> Previous:</B> <A NAME=tex2html33 HREF="node2.html"> Our Proposal</A>
+<BR> <HR> <P>
+<H1><A NAME=SECTION00030000000000000000> Specification</A></H1>
+<P>
+In Tiger all the computations are on 64-bit words, in
+little-endian/2-complement representation. We use three 64-bit
+registers called a, b, and c as the intermediate hash values. These
+registers are initialized to <IMG ALIGN=MIDDLE ALT="" SRC="img5.gif"> which is:
+<P>
+<PRE> a = 0x0123456789ABCDEF
+ b = 0xFEDCBA9876543210
+ c = 0xF096A5B4C3B2E187
+</PRE>
+<P>
+Each successive 512-bit message block is divided into eight 64-bit words x0,
+x1, ..., x7, and the following computation is performed to update <IMG ALIGN=MIDDLE ALT="" SRC="img6.gif"> to
+<IMG ALIGN=MIDDLE ALT="" SRC="img7.gif">.
+<P>
+This computation consists of three passes, and between each of them there is a
+<i> key schedule</i> --- an invertible transformation of the input data which
+prevents an attacker forcing sparse inputs in all three rounds. Finally there
+is a feedforward stage in which the new values of a, b, and c are combined with
+their initial values to give <IMG ALIGN=MIDDLE ALT="" SRC="img8.gif">:
+<P>
+<PRE> save_abc
+ pass(a,b,c,5)
+ key_schedule
+ pass(c,a,b,7)
+ key_schedule
+ pass(b,c,a,9)
+ feedforward
+</PRE>
+<P>
+where
+<P>
+<OL><LI> <tt> save_abc</tt> saves the value of <IMG ALIGN=MIDDLE ALT="" SRC="img9.gif">
+<P>
+<PRE> aa = a ;
+ bb = b ;
+ cc = c ;
+</PRE>
+<P>
+<LI> <tt> pass(a,b,c,mul)</tt> is
+<P>
+<PRE> round(a,b,c,x0,mul);
+ round(b,c,a,x1,mul);
...
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