Re: [TLS] OCSP must staple

Yoav Nir <ynir.ietf@gmail.com> Mon, 09 June 2014 07:12 UTC

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From: Yoav Nir <ynir.ietf@gmail.com>
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Date: Mon, 9 Jun 2014 10:12:48 +0300
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References: <097101cf7aa7$17f960a0$47ec21e0$@digicert.com> <4AA8E7B7-A19D-4E65-AF18-C4D02A513652@ieca.com> <538EF79B.3000506@cs.tcd.ie> <CAMm+LwgTnva9jJgVfkaOZ1qP0Rk3w-mFfepnubosgtrCEARv=g@mail.gmail.com> <539069CC.5010304@cs.tcd.ie> <CAFewVt4p4rJ738Yo=XQm6T_jyvG3TnJsSQ5HDZDrqAkyNDa7tg@mail.gmail.com> <20140605173223.GK27883@mournblade.imrryr.org> <20140607164945.GA23329@roeckx.be> <20140607170619.GC27883@mournblade.imrryr.org> <2A0EFB9C05D0164E98F19BB0AF3708C7130F434F7A@USMBX1.msg.corp.akamai.com> <20140607184737.GD27883@mournblade.imrryr.org> <2A0EFB9C05D0164E98F19BB0AF3708C7130F434F7D@USMBX1.msg.corp.akamai.com> <155f01cf82ce$7cfa8360$76ef8a20$@digicert.com> <2A0EFB9C05D0164E98F19BB0AF3708C7130F434FB5@USMBX1.msg.corp.akamai.com> <539549A8.1040008@gmail.com>
To: Kyle Hamilton <aerowolf@gmail.com>
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Subject: Re: [TLS] OCSP must staple
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On Jun 9, 2014, at 8:44 AM, Kyle Hamilton <aerowolf@gmail.com> wrote:
> 
> On the other hand, I think that relying on a stapled response is perhaps
> shortsighted, as it potentially opens a window of vulnerability.  Say
> the OCSP response is valid for 7 days (the maximum time that EV cert
> OCSP responses can be valid for): if the cert is revoked on day 2,
> that's still 5 and change days of potential validity.  This is the kind
> of vulnerability that clients can use the OCSP nonce extension to
> protect themselves from, but it only works if it's used and queried from
> the OCSP responder by the client itself.  Thus, the proposal to prevent
> clients from checking OCSP from the source in the presence of an "OCSP
> must staple" extension is harmful to user security and thus wrong-minded.

I think one of the points of “must staple” is that it allows the CA to shorten the TTL without having its OCSP responder overwhelmed with traffic from clients.

Yoav