corporate IT administrators [LWN.net]

corporate IT administrators

Posted Mar 7, 2016 16:43 UTC (Mon) by nim-nim (subscriber, #34454)
In reply to: corporate IT administrators by josh
Parent article: TLS certificate management on Android

If you want to make sure your malware proxy is not modifying traffic you need integrity, ie digital signatures. Hiding the traffic from the malware checker defeats its purpose.

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corporate IT administrators

Posted Mar 7, 2016 19:22 UTC (Mon) by josh (subscriber, #17465) [Link] (3 responses)

That's an interesting concept that I haven't seen brought up in such discussions before. While I'd still never want to use such a network myself, it'd certainly be *interesting* to have a protocol that could support integrity protection that prevents MITM modification, while still allowing monitoring. That could be useful in an environment with regulatory compliance issues, and it'd be somewhat less problematic than allowing MITM.

That said, while such an approach might get some of the existing IT departments running MITM proxies to switch, it might also get IT departments that currently *don't* break HTTPS to try to use that interception mechanism when they would otherwise have had no such option. So I'm not entirely convinced that such an option would be a net positive.

corporate IT administrators

Posted Mar 8, 2016 2:17 UTC (Tue) by flussence (guest, #85566) [Link] (2 responses)

>While I'd still never want to use such a network myself, it'd certainly be *interesting* to have a protocol that could support integrity protection that prevents MITM modification, while still allowing monitoring.

SSL/TLS itself is already capable of that: the command `openssl ciphers -v 'eNULL:!aNULL'` will give you a list of cipher suites (including one in TLS 1.2) which send the data in clear text but cryptographically signed. Naturally, this won't work in a browser.

corporate IT administrators

Posted Mar 8, 2016 6:12 UTC (Tue) by josh (subscriber, #17465) [Link] (1 responses)

That would make it cleartext end-to-end, rather than encrypted from the site to the proxy and the proxy to the browser, and only cleartext-with-integrity-protection to the proxy itself.

corporate IT administrators

Posted Mar 8, 2016 17:59 UTC (Tue) by nybble41 (subscriber, #55106) [Link]

It should still be possible to implement cleartext-with-integrity-protection without changing TLS per se, though you would need an out-of-band protocol for communication between the client and the proxy. The client just needs to give the proxy the decryption key which it derives from the DH master secret. If it keeps the corresponding HMAC secret to itself then the proxy can decrypt the traffic, but not tamper with it; end-to-end authenticity would thus be preserved.