Re: [kitten] AD sponsoring draft-hansen-scram-sha256

Simon Josefsson <simon@josefsson.org> Mon, 16 February 2015 11:23 UTC

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From: Simon Josefsson <simon@josefsson.org>
To: Alexey Melnikov <alexey.melnikov@isode.com>
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Date: Mon, 16 Feb 2015 12:22:53 +0100
In-Reply-To: <54E1D009.2050408@isode.com> (Alexey Melnikov's message of "Mon, 16 Feb 2015 11:10:01 +0000")
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Subject: Re: [kitten] AD sponsoring draft-hansen-scram-sha256
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Alexey Melnikov <alexey.melnikov@isode.com> writes:

> Hi Simon,
>
> On 16/02/2015 09:48, Simon Josefsson wrote:
>  [snip]
>> A suggested (not even mandated) pbkdf iteration count of at least 4096
>> is unchanged since RFC 5802 -- I'd really like to see that be
>> significantly higher.  Back in 2000 an iteration count of 1000 was
>> recommended as the minimum.  Surely computational power has increased
>> more than a factor of four since then.
> I've heard complains from developers that 4096 with SHA-1 is too high
> for current Android phones. It would be good to get more information
> on performance before changing the number.

You will always hear complaints from developers that security features
adds computational and other resource costs.  When that happens, I
prefer asking myself whether the threat model motivates the cost or not.

/Simon