<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Consolas;
panose-1:2 11 6 9 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
p.MsoPlainText, li.MsoPlainText, div.MsoPlainText
{mso-style-priority:99;
mso-style-link:"Plain Text Char";
margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
span.PlainTextChar
{mso-style-name:"Plain Text Char";
mso-style-priority:99;
mso-style-link:"Plain Text";
font-family:"Calibri","sans-serif";}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="#0563C1" vlink="#954F72">
<div class="WordSection1">
<p class="MsoPlainText">This seems the best existing mail to add to. I promised some time back to forward comments from someone on our security team. My apologies for the delay. I’ve summarized these point on recent conference calls.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">I also have some concerns with supporting ISO 14533-2. Limiting support in Office to –T and –A (which we don’t support today) would reduce the number of customers that can use the feature. As David mentioned
it would be great from a security and data integrity perspective if everyone required a timestamp to create a digital signature. We investigated making XAdES –T the default for Office 2013, however there are no free timestamp servers available for customers
to use. This would limit the feature to customers that run and maintain their own timestamp server or have one accessible to them. We did not feel that it was wise to limit the feature just to customers who have timestamp servers available as many customers
use the Office digital signature feature for different reasons. Some customers simply use it as a way of inking their name on a document, which they plan on printing out. In this case requiring a timestamp would block them from using our feature to accomplish
their goals. </span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Office hasn’t received any customer requests to support XAdES –A or counter signatures. When we last investigated adding support for them, they didn’t make the cut because we didn’t have data to support the
need and our team had other feature priorities. </span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">In terms of the hashing algorithm compromise that has always been a concern with digital signatures and was why –A was created. It appears that the research has discovered a flaw in the existing XAdES –A implementation
which would still allow tampering with signed contents to go undetected in the event of an algorithm failure. In Office 2013 we introduced a new feature to warn customers that their digital signatures contain algorithms which are considered weak cryptographically
and may end up failing in the near future (today only MD5 appears in this category by default). We made this feature configurable via group policy so that customers could determine what the right policy is for their scenarios and then either warn their users
or block signature creation and fail validation.</span><o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">-----Original Message-----<br>
From: eb2mmrt@gmail.com [mailto:eb2mmrt@gmail.com] On Behalf Of MURATA Makoto<br>
Sent: Thursday, July 17, 2014 3:11 AM<br>
To: SC34<br>
Subject: XAdES in OPC: Further comments from Japan</p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Dear colleagues,<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">I gave a report of the Prague meeting in the latest meeting<o:p></o:p></p>
<p class="MsoPlainText">of the Japanese SC34 mirror. Now, XAdES experts in Japan<o:p></o:p></p>
<p class="MsoPlainText">attended this meeting. They gave some comments (shown<o:p></o:p></p>
<p class="MsoPlainText">below). They plan to attend the Kyoto meeting.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">XAdES-C and XAdES-X-L are alternative choices. XAdES-C does not depend on XAdES-X-L, and XAdES-X-L does not depend on XAdES-C.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">XAdES-C and XAdES-X-L are intermediate forms rather than distributable forms.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Among the profiles of XAdES, it is only XAdES-A that provides long-term digital signature.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Although XAdES-A is not the only way for providing long-term digital signature, it is a standalone solution: no external data is required.<o:p></o:p></p>
<p class="MsoPlainText">Meanwhile, XAdES-X-L or XAdES-C can be combined with some external data for providing long-term digital signature. In other words, neither XAdES-X-L nor XAdES-C provides a complete solution.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">XAdES-X-L does not require the use of XAdES-C or XAdES-X.<o:p></o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText"><o:p> </o:p></p>
<p class="MsoPlainText">Regards,<o:p></o:p></p>
<p class="MsoPlainText">Makoto<o:p></o:p></p>
</div>
</body>
</html>