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Comment by ikawe | Hacker News Reader

The article says:

    You want to make sure that you don't see the text "_DHE_" in the list of ciphersuites.`

And the article links to https://www.howsmyssl.com/, which shows me these in my list of cipher suites:

    TLS_DHE_RSA_WITH_AES_128_GCM_SHA256
    TLS_DHE_RSA_WITH_CHACHA20_POLY1305_SHA256
    TLS_DHE_RSA_WITH_AES_128_CBC_SHA

But the heading says: "Your SSL client is Probably Okay."

Is https://www.howsmyssl.com/ out of date? Shouldn't I be seeing some kind of warning?

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There's nothing inherently wrong with the DHE ciphersuites, as long as the server provides secure parameters. Since weakdh is really a server-side issue, and howsmyssl.com is a client-side test, a warning doesn't really make sense.

... but clients can guard against weak server-side DHE by rejecting DHE ciphersuites. So I think the GP was correct that this diagnostic should be updated.

No, because as agwa pointed out, howsmyssl checks client security. There's nothing wrong with a DHE cipher suite and it can be used in a secure manner quite easily. Since this is wholly on the server, and howsmyssl has no way of testing a server you're connecting to, then there's no possible way for it to know if your specific connections are okay or not. Based solely on the client suites tested, DHE would still be considered secure. It's only the interaction with an insecure server that makes it insecure.

weakdh can be mitigated client side. The website[0] itself has a test for it, which works by requesting this file[1].

[0]: https://weakdh.org/

[1]: https://dhe512.zmap.io/dhe512test.js

The Qualys SSL Labs tester checks for weak DH parameters as part of its report: https://www.ssllabs.com/ssltest/

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