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Sweet32: Birthday attacks on 64-bit block ciphers in TLS and OpenVPN

140 点作者 pedro84超过 8 年前

8 条评论

CiPHPerCoder超过 8 年前
To put this in context: You should have been avoiding 64-bit block ciphers to begin with.<p><a href="https:&#x2F;&#x2F;gist.github.com&#x2F;tqbf&#x2F;be58d2d39690c3b366ad" rel="nofollow">https:&#x2F;&#x2F;gist.github.com&#x2F;tqbf&#x2F;be58d2d39690c3b366ad</a><p>Furthermore, as the article says from the getgo, birthday attacks are not <i>new</i>. They are a known problem.<p>What&#x27;s new is someone wrote a paper describing a practical attack, and actually bothered to generate enough traffic to exploit the birthday bound of a 64-bit block cipher.<p>Your takeaway from this should be:<p><pre><code> - If it&#x27;s not AES or CHACHA20, disable it. - If it&#x27;s not AES_GCM or CHACHA20_POLY1305, consider disabling it.</code></pre>
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pedro84超过 8 年前
From the article: &quot;But the take-away is this: triple-DES should now be considered as “bad” as RC4.&quot;<p>OpenSSL developer Mark Cox says: &quot;tldr: &quot;Low&quot;, Don&#x27;t Panic!&quot; <a href="https:&#x2F;&#x2F;twitter.com&#x2F;iamamoose&#x2F;status&#x2F;768431734547484672" rel="nofollow">https:&#x2F;&#x2F;twitter.com&#x2F;iamamoose&#x2F;status&#x2F;768431734547484672</a><p>The researcher site is <a href="https:&#x2F;&#x2F;sweet32.info&#x2F;" rel="nofollow">https:&#x2F;&#x2F;sweet32.info&#x2F;</a><p>And RedHat has a nice writeup as well: <a href="https:&#x2F;&#x2F;access.redhat.com&#x2F;articles&#x2F;2548661" rel="nofollow">https:&#x2F;&#x2F;access.redhat.com&#x2F;articles&#x2F;2548661</a>
qwertyuiop924超过 8 年前
Who&#x27;s still using 3DES? That should already be a shooting offense anywhere where security matters.
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rasz_pl超过 8 年前
TLDR: ~800GB sniffed in one session to perform the attack. Only practical if you never log off your torrent VPN.
erichocean超过 8 年前
At what point does using TLS become malpractice? At what point does any software that links to OpenSSL become immediately suspect?<p>And TLS as deployed isn&#x27;t secure <i>even when it works</i> whenever you don&#x27;t trust the certificate authorities. Which is always.<p>Yes, I get that these are mega standards&#x2F;libraries with a gazillion knobs, some of which are secure. But maybe kitchen sink crypto isn&#x27;t the way to go? When will we say enough is enough and do something about it? For my part, I switched to using NaCl with public key pinning a few years ago and haven&#x27;t looked back.<p>&#x2F;sigh
Panino超过 8 年前
Yet another example of key size not being the only thing to consider.<p>Also: OpenVPN&#x27;s default cipher is blowfish? That would have been a great choice <i>20 years ago</i>, but not now. It shouldn&#x27;t even be supported in 2016.
yalogin超过 8 年前
Why did Openssl only disable TDES and not Blowfish?
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dang超过 8 年前
We changed the URL from <a href="https:&#x2F;&#x2F;www.openssl.org&#x2F;blog&#x2F;blog&#x2F;2016&#x2F;08&#x2F;24&#x2F;sweet32&#x2F;" rel="nofollow">https:&#x2F;&#x2F;www.openssl.org&#x2F;blog&#x2F;blog&#x2F;2016&#x2F;08&#x2F;24&#x2F;sweet32&#x2F;</a> to this post because it seems more explanatory.<p>There&#x27;s also <a href="http:&#x2F;&#x2F;blog.cryptographyengineering.com&#x2F;2016&#x2F;08&#x2F;attack-of-week-64-bit-ciphers-in-tls.html" rel="nofollow">http:&#x2F;&#x2F;blog.cryptographyengineering.com&#x2F;2016&#x2F;08&#x2F;attack-of-we...</a>, via <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=12353314" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=12353314</a>.