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Re: [PATCH v6 3/5] random: use SipHash in place of MD5

From "Jason A. Donenfeld" <Jason@zx2c4.com>
Newsgroups linux.kernel
Subject Re: [PATCH v6 3/5] random: use SipHash in place of MD5
Date 2016-12-16 23:30 +0100
Message-ID <sP9aN-14V-9@gated-at.bofh.it> (permalink)
References <sP8y5-Cy-13@gated-at.bofh.it> <sP918-11E-21@gated-at.bofh.it>
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Hi Andy,

> Agreed.  A simpler contruction would be:
>
> chaining++;
> output = H(chaining, secret);
>
> And this looks a whole lot like Ted's ChaCha20 construction.

In that simpler construction with counter-based secret rekeying and in
Ted's ChaCha20 construction, the issue is that every X hits, there's a
call to get_random_bytes, which has variable performance and entropy
issues. Doing it my way with it being time based, in the event that
somebody runs ` :(){ :|:& };:`, system performance doesn't suffer
because ASLR is making repeated calls to get_random_bytes every 128 or
so process creations. In the time based way, the system performance
will not suffer.

Jason

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Thread

Re: [PATCH v6 3/5] random: use SipHash in place of MD5 "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-16 22:50 +0100
  Re: [PATCH v6 3/5] random: use SipHash in place of MD5 Andy Lutomirski <luto@amacapital.net> - 2016-12-16 23:20 +0100
    Re: [PATCH v6 3/5] random: use SipHash in place of MD5 "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-16 23:30 +0100
  Re: [PATCH v6 3/5] random: use SipHash in place of MD5 "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-16 23:20 +0100

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