<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Mar 6, 2015 at 2:05 PM, Christian Georg <span dir="ltr"><<a href="mailto:christian.georg@cologne-intelligence.de" target="_blank">christian.georg@cologne-intelligence.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal">Hi all,<u></u><u></u></p></div></div></blockquote><div><br></div><div>Christian,<br><br></div><div>I might be able to save you some time.<br><br></div><div>I wrote an SSL/TLS client test for the SSL Labs web site; you can find it here: <a href="https://dev.ssllabs.com/ssltest/viewMyClient.html">https://dev.ssllabs.com/ssltest/viewMyClient.html</a> If you can visit this page from the client/device and examine the output, you'll find there everything you need to know. There are a couple of other similar services. I keep a list here: <a href="https://github.com/ssllabs/research/wiki/Assessment-Tools">https://github.com/ssllabs/research/wiki/Assessment-Tools</a> (look under Client Assessment).<br><br></div><div>If you can't do that, you can install my Apache module called mod_sslhaf, which will dump contents of ClientHello to the server log. This approach isn't as good as the previous one, but might be good enough for your use case. You can find the module here: <a href="https://github.com/ssllabs/sslhaf">https://github.com/ssllabs/sslhaf</a><br></div><div> <br><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div link="#0563C1" vlink="#954F72" lang="DE"><div><p class="MsoNormal"></p>
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<p class="MsoNormal"><span lang="EN-GB">I am trying to get detailed info on the protocols and cipher suites supported by a client app. Main goal is to verify that the constraints on protocols versions and cipher suites we are using within an app are working
correctly. (so it is not about the cipher suites that are theoretically available on a mobile device)
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">I was planning to use openssl s_server for this task. I am opening s_server on different ports each with a specific protocol version (-ssl2, -ssl3, -tls1…). On some of the ports a handshake should be successful on others
not. <u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">The tricky part are the supported cipher suites. When using the –www option I can return a website to the client showing the cipher suites that provide a match, which gets pretty close to what I want in a browser. Now
here are my challenges.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Challenge 1: Getting a list of ALL Ciphersuites
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">I would like to get info on all cipher suites supported (preferred) by the client . The –www option does only show the cipher suites with a match. So any cipher suite not supported by openssl will not be listed. When
checking my browser with qualys SSl Lab I noticed that the following three ciphersuites are showing up on the qualys report but not on the s_server page.
<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">I do not see them as a risk, but what if some exotic weak ciphers are enabled within the app. It is my understanding that during a handshake a list of all preferred ciphers is send from the client to the server. How can
I get access to this info?<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Challenge 2: How do I get the info into a log file on the server rather than sending it back as a website?<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">The approach described above is working fine for browsers but what about consuming webservices? I am able to redirect the webservices to my openssl s_server and perform the handshake (even so the SOAP or REST Interface
will then throw an error). But I could not find an option on getting the info written into the Logfile (in a human readable way) even with all logging I found enabled (-state -debug -msg –tlsextdebug -trace) I could not find the info in a human readable way.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Any recommendations on how I can solve my issues without changing the openssl code and add this manually?<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Cheers<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><br>
Chris <u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
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<br></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature">Ivan</div>
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