Re: [dtn-security] Re: [dtn-dev] Re: SDNV-new

Howard Weiss <howard.weiss@sparta.com> Fri, 27 May 2005 19:19 UTC

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Date: Fri, 27 May 2005 15:19:26 -0400
From: Howard Weiss <howard.weiss@sparta.com>
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To: Scott Burleigh <Scott.Burleigh@jpl.nasa.gov>
CC: dtn-security@mailman.dtnrg.org, dtn-dev@mailman.dtnrg.org
Subject: Re: [dtn-security] Re: [dtn-dev] Re: SDNV-new
References: <200505241854.j4OIsx724035@smtp-bedford-dr.mitre.org> <42944BEF.7090007@cs.tcd.ie> <20050525152006.GA7633@pisco.cs.berkeley.edu> <42949E83.9050000@cs.tcd.ie> <20050525163707.GB14911@pisco.cs.berkeley.edu> <4294ABB9.5010009@jpl.nasa.gov> <20050525172205.GD14911@pisco.cs.berkeley.edu> <20050526002442.GE28634@pisco.cs.berkeley.edu> <4295F1AF.5020607@jpl.nasa.gov> <20050526184825.GE4301@pisco.cs.berkeley.edu> <42961ED1.80400@jpl.nasa.gov>
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For keys, we need (at a min) 128 bits for a symmetric key and (at a min) 
1024 bits for an asymmetric key.  But the key sizes will vary - 512 bits 
may not be unheard of for a symmetric key and 2048 for an asymmetric.

Howie

Scott Burleigh wrote:

> Michael Demmer wrote:
>
>>> I don't much care one way or another.  Do we really think we're
>>> likely to need to represent numbers bigger than (2*68) - 1 in SDNVs?
>>>   
>>
>>
>> Very doubtful if all they're used for is lengths, maybe so if they're
>> used for other things like crypto keys and such.
>>
> If we think we really are going to use SDNVs for crypto keys then I 
> think 1/2/3/4/6/8/12/16 isn't going to be enough, because crypto keys 
> only seem to get longer as the years go by.  I think that would argue 
> for either the original SDNV-8 (or -16) scheme or else an encoding 
> along the lines of 1/2/4/8/16/32/64/128.
>
> If not -- that is, if we're going use ordinary LV structures (an 8-bit 
> length followed by that many bytes of content) for encryption keys -- 
> then I don't see any point in moving away from 1/2/3/4/5/6/7/8.
>
> Scott
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Howard Weiss
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