Re: [TLS] New Cached info draft
Michael D'Errico <mike-list@pobox.com> Wed, 31 March 2010 15:46 UTC
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Date: Wed, 31 Mar 2010 08:52:37 -0700
From: Michael D'Errico <mike-list@pobox.com>
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Subject: Re: [TLS] New Cached info draft
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Stefan Santesson wrote: > On 10-03-30 7:30 PM, "Brian Smith" <brian@briansmith.org> wrote: >> It is good to keep the maximum size of extensions small so that the server >> can allocate and reuse fixed-size buffers that are as small as possible. I >> don't see the use for allowing multiple values per information type, but at >> least I think a small cap on the total size of the extension_data (say, 1KB) >> would be useful. There's no need for a server to waste resources to support >> clients that send dozens, hundreds, or thousands of digests. > > I think that is a good limitation. Suggesting: > > struct { > CachedInformationType type; > opaque digest_value<0..8>; > } CachedObject; > > struct { > CachedObject cached_info<1..1024>; > } CachedInformation; I haven't been able to totally keep up with the progress of this draft or to follow the discussion, but I think it's a bad idea to artificially limit the size of anything to 1024 bytes. We can handle 8-bit, 16-bit and 24-bit sizes, and there is no precedent for choosing anything other than the full range. A single certificate can be 16MB! If somebody wants to use small fixed-size buffers, then they can check the length of the vector to see if it will fit. If it won't fit, then they have to deal with it somehow. Putting a cap of 1024 bytes in the spec. does nothing to change this -- you still have to check the size since an attacker isn't going to play by the rules. This idea has buffer overflow written all over it. Mike
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Stefan Santesson
- [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Kemp, David P.
- Re: [TLS] New Cached info draft Adam Langley
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Marsh Ray
- Re: [TLS] New Cached info draft Marsh Ray
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Simon Josefsson
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Adam Langley
- Re: [TLS] New Cached info draft Brian Smith
- Re: [TLS] New Cached info draft Brian Smith
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Martin Rex
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Brian Smith
- Re: [TLS] New Cached info draft Martin Rex
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Brian Smith
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Michael D'Errico
- Re: [TLS] New Cached info draft Marsh Ray
- Re: [TLS] New Cached info draft Brian Smith
- Re: [TLS] New Cached info draft Adam Langley
- Re: [TLS] New Cached info draft Stefan Santesson
- Re: [TLS] New Cached info draft Martin Rex
- Re: [TLS] New Cached info draft Martin Rex
- Re: [TLS] New Cached info draft Marsh Ray
- Re: [TLS] New Cached info draft Martin Rex