Re: [IPsec] Password-Based Auth: Two criteria comments

Yaron Sheffer <yaronf.ietf@gmail.com> Mon, 22 March 2010 18:27 UTC

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Date: Mon, 22 Mar 2010 20:28:22 +0200
From: Yaron Sheffer <yaronf.ietf@gmail.com>
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Subject: Re: [IPsec] Password-Based Auth: Two criteria comments
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Hi David,

I think both of these are (correct) requirements, rather than criteria. 
None of the algorithms I've seen care whether it's a 6-char ASCII 
password, or 512 truly-random bits. None of them say anything about 
management (with the possible exception of the "augmented" algorithms 
where the "augmentation" has some bearing on management).

Regarding management, -01 says this, which I think is in line with what 
you're saying:

It is noted that some features (such as support for password expiry)
    and some security criteria (such as resistance to server compromise)
    are very important for the "teleworker" use case.  This document is
    limited to the use of password-based authentication to achieve trust
    between gateways, and for this use case, these features and criteria
    are of questionable value.

Thanks,
	Yaron


On 22.3.2010 20:18, Black_David@emc.com wrote:
> Summarizing what I said in the meeting:
>
> (1) The performance criteria should include performance with large complex secrets (e.g., pre-shared keys), not just the smaller passwords that people can reasonably be expected to remember.
>
> This is because a password-based authentication mechanism may be usefully applied to shared secret authentication implementations that derive a supposedly strong secret solely from a password (see the discussion of pre-shared key authentication in Section 2.15 of RFC 4306).  Password-based authentication would provides some defense against this and other key generation weaknesses.  The original password that was used to generate the shared secret may no longer be available, so good performance on large complex secrets would enable password based authentication to use the derived (supposedly strong) secret as the password.
>
> (2) Management (e.g., password change, password policy) is not mentioned in the criteria document.  This is good.
>
> Keeping management orthogonal (i.e., out of scope of this criteria discussion) is (IMHO) a good thing, as management techniques and requirements may vary widely across classes of implementations.
>
> Thanks,
> --David
> ----------------------------------------------------
> David L. Black, Distinguished Engineer
> EMC Corporation, 176 South St., Hopkinton, MA  01748
> +1 (508) 293-7953             FAX: +1 (508) 293-7786
> black_david@emc.com        Mobile: +1 (978) 394-7754
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