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Re: [TLS] TLS 1.3 draft-07 sneak peek

Jeffrey Walton <noloader@gmail.com> Wed, 08 July 2015 18:28 UTC

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Date: Wed, 08 Jul 2015 14:28:50 -0400
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From: Jeffrey Walton <noloader@gmail.com>
To: Eric Rescorla <ekr@rtfm.com>
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Subject: Re: [TLS] TLS 1.3 draft-07 sneak peek
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> Let's distinguish between two different uses of SHA-1:
>
> 1. In certificates.
> 2. In TLS signatures.
>
Marc Steven is engineering collisions on SHA-1 in 2^61. See the
HashClash homepage at https://marc-stevens.nl/p/hashclash/. That's
well within reach of many attackers given how cheaply one can purchase
compute time on EC2 or Nova.

1024-bit RSA has been basically been deprecated, and it provided about
80-bits of security. I'm not sure what economic models those
speculating on attacks are following, but adversaries usually perform
the most economical attack first, not last.

It kind of reminds me of the CAs ignoring the warnings about MD5. And
then this happened: https://www.win.tue.nl/hashclash/rogue-ca/.

Jeff

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