Re: [TLS] chacha to replace RC4 (was: Salsa vs. ChaCha)

Nikos Mavrogiannopoulos <nmav@redhat.com> Fri, 06 December 2013 13:22 UTC

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From: Nikos Mavrogiannopoulos <nmav@redhat.com>
To: Robert Ransom <rransom.8774@gmail.com>
Date: Fri, 06 Dec 2013 14:22:31 +0100
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Cc: tls@ietf.org
Subject: Re: [TLS] chacha to replace RC4 (was: Salsa vs. ChaCha)
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On Fri, 2013-12-06 at 04:54 -0800, Robert Ransom wrote:

> The other issue in replacing RC4 with Salsa20 or ChaCha is that the
> currently available efficient implementations of Salsa20 and ChaCha
> encrypt a whole message at once, rather than incrementally generating a
> stream as with RC4.  (And modifying them to do the latter would add
> considerable complexity -- if it must be done, I would generate 3 or 4
> blocks of output at a time and have some other piece of code XOR the
> keystream with the data.)
> 
> Salsa20 and ChaCha are meant to be used as in Adam Langley's draft, not
> as replacements for RC4.

Reading that again, I believe that what you say above doesn't make
sense. Why Chacha suits better in Adam's draft, but doesn't as a 
replacement of RC4?

regards, 
Nikos