Re: [xmpp] IQ Handling vulnerabilities
Alexander Holler <holler@ahsoftware.de> Tue, 11 February 2014 17:29 UTC
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Date: Tue, 11 Feb 2014 18:28:21 +0100
From: Alexander Holler <holler@ahsoftware.de>
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To: Dave Cridland <dave@cridland.net>
References: <CAOb_FnxS-dMT85N7LHj5M9JWk3pL85=ugrDqaT7j5d28HBr0Cw@mail.gmail.com> <CF194491.38AD3%jhildebr@cisco.com> <2F5E925F-021D-408E-91D9-3CC5BEB6BEC6@nostrum.com> <48F4D361-4403-47E6-862D-FBDDDEBCC642@xnyhps.nl> <CF1A369C.38BE2%jhildebr@cisco.com> <CAKHUCzyCwKbmnUoXLHW=XzYbiFrcg-dQsDojGUnA-_r3qK+_Vg@mail.gmail.com> <CF1A4928-54B5-4A95-9A4B-0EC572A3CDBD@cisco.com> <CF1E56C5.38F45%jhildebr@cisco.com> <B671D7DA-CE9A-4A2C-8EDE-BF94F5F6FE82@xnyhps.nl> <52FA165B.8050901@ahsoftware.de> <CAKHUCzzhxKLbkNE=WjtP9S6XWm14-5e7Ut150x4k1akegm+1Qw@mail.gmail.com> <52FA3E53.3060009@ahsoftware.de> <0C2D606F-F718-4B07-A0A8-329C547D1BD8@xnyhps.nl> <52FA4D02.5050907@ahsoftware.de> <52FA5060.9040303@ahsoftware.de> <CAKHUCzyv1cMiZn9OkAXOeaMs-Ti8Z32K-gjygc1dMM9NVLqVPQ@mail.gmail.com>
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Cc: XMPP Working Group <xmpp@ietf.org>
Subject: Re: [xmpp] IQ Handling vulnerabilities
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Am 11.02.2014 18:06, schrieb Dave Cridland: > On Tue, Feb 11, 2014 at 4:31 PM, Alexander Holler <holler@ahsoftware.de>wrote: > >> which I interpret such, that, besides using a hash from hash (so no new >> source), the ID consists of just the first 10 characters of the 40 of a >> sha1. And then you argument with the collision rate of sha1? >> >> > Oh, I see what you mean now. > > Yes, on that model the collision would probably happen much sooner. > > It's a collision space of 2^40, though, so a birthday attack would hit > after about 1.3 million stanzas by my calculations. The chance of this > causing a problem seems pretty low. Based on the assumption that a hash of a hash has the same collision space as the hash itself. Since I'm long out of university and academics and I'm unfortunately quiet out of practice in dealing with maths (even if I liked to do so, but math isn't needed that often in real world computing than universities tend to teach), I'm not going into a discussion about how (un)likely it is that two consequent outputs of such a homegrewn algorithm (sorry for that term) are different. I just wanted to raise awareness that whatever is used should still produce unique numbers (for a short period of time) and not just numbers which are unpredictable. It's easy to predict that a serial counter is unique for some time, but I don't see that when someone uses a series like whateverhash(whateverhash(...) and I wouldn't trust such without having a deeper look at it. Regards, Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Philipp Hancke
- [xmpp] IQ Handling vulnerabilities Kevin Smith
- Re: [xmpp] IQ Handling vulnerabilities Joe Hildebrand (jhildebr)
- Re: [xmpp] IQ Handling vulnerabilities Matt Miller
- Re: [xmpp] IQ Handling vulnerabilities Peter Saint-Andre
- Re: [xmpp] IQ Handling vulnerabilities Ben Campbell
- Re: [xmpp] IQ Handling vulnerabilities Thijs Alkemade
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Kevin Smith
- Re: [xmpp] IQ Handling vulnerabilities Kevin Smith
- Re: [xmpp] IQ Handling vulnerabilities Joe Hildebrand (jhildebr)
- Re: [xmpp] IQ Handling vulnerabilities Dave Cridland
- Re: [xmpp] IQ Handling vulnerabilities Kevin Smith
- Re: [xmpp] IQ Handling vulnerabilities Joe Hildebrand (jhildebr)
- Re: [xmpp] IQ Handling vulnerabilities Waqas Hussain
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Ben Campbell
- Re: [xmpp] IQ Handling vulnerabilities Thijs Alkemade
- Re: [xmpp] IQ Handling vulnerabilities Waqas Hussain
- Re: [xmpp] IQ Handling vulnerabilities Kevin Smith
- Re: [xmpp] IQ Handling vulnerabilities Dave Cridland
- Re: [xmpp] IQ Handling vulnerabilities Kevin Smith
- Re: [xmpp] IQ Handling vulnerabilities Thijs Alkemade
- Re: [xmpp] IQ Handling vulnerabilities Thijs Alkemade
- Re: [xmpp] IQ Handling vulnerabilities Ashley Ward
- Re: [xmpp] IQ Handling vulnerabilities Peter Saint-Andre
- Re: [xmpp] IQ Handling vulnerabilities Peter Saint-Andre
- Re: [xmpp] IQ Handling vulnerabilities Dave Cridland
- Re: [xmpp] IQ Handling vulnerabilities Ashley Ward
- Re: [xmpp] IQ Handling vulnerabilities Peter Saint-Andre
- Re: [xmpp] IQ Handling vulnerabilities Joe Hildebrand (jhildebr)
- Re: [xmpp] IQ Handling vulnerabilities Thijs Alkemade
- Re: [xmpp] IQ Handling vulnerabilities Joe Hildebrand (jhildebr)
- Re: [xmpp] IQ Handling vulnerabilities Dave Cridland
- Re: [xmpp] IQ Handling vulnerabilities Dave Cridland
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Dave Cridland
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Thijs Alkemade
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Dave Cridland
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Alexander Holler
- Re: [xmpp] IQ Handling vulnerabilities Joe Hildebrand (jhildebr)