[Opensim-dev] Always mutable assets in OpenSim -- does it make sense?

[Hurliman, John]

You can overwrite assets on the SL grid today if you can manage an MD5 collision. If you break SHA1, I would be worrying a lot more about the root CAs that have signed nearly every SSL certificate on the web.

https://www.verisign.com/repository/root.html

John

> -----Original Message-----
> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev- 
> bounces at lists.berlios.de] On Behalf Of Frisby, Adam
> Sent: Wednesday, December 17, 2008 1:06 AM
> To: opensim-dev at lists.berlios.de
> Subject: Re: [Opensim-dev] Always mutable assets in OpenSim -- does it 
> make sense?
> 
> Be careful here however,
> 
> 
> 
> Because if the hashing algorithm you choose ever gets 'broken' where 
> it's possible to calculate a binary against a desired result, then 
> people can potentially overwrite existing assets, etc.  A long hash 
> tends to act as a good barrier against this. (256bit+ is ideal.)
> 
> 
> 
> Regards,
> 
> 
> 
> Adam
> 
> 
> 
> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev- 
> bounces at lists.berlios.de] On Behalf Of Stefan Andersson
> Sent: Wednesday, 17 December 2008 12:59 AM
> To: opensim-dev at lists.berlios.de
> Subject: Re: [Opensim-dev] Always mutable assets in OpenSim -- does it 
> make sense?
> 
> 
> 
> First step would probably be to implement the sha-based binary store 
> that you bring up and that we've discussed earlier, so that the 
> immutables at least share the same binary data row. Right now, I 
> believe we're seing massive duplication when people export/import 
> content between worlds. Storing the binaries separately by sha key 
> would probably be an low hanging fruit.
> 
> I would say that it's probably very much up to the service (aka 'the
> grid') how assets should be managed. On an grid that employs a 
> consumer/producer division (like a fantasy game) you could probably 
> reap dead assets quite aggressively. In a SL business model, it 
> becomes harder, as they have to ensure consistent user experience in a 
> heterogenous environment.
> 
> Best regards,
> Stefan Andersson
> Tribal Media AB
> 
>> Date: Sun, 14 Dec 2008 14:48:01 +0900 From: mmazur at gmail.com To:
>> opensim-dev at lists.berlios.de Subject: [Opensim-dev] Always mutable 
>> assets in OpenSim -- does it make sense?
>> 
>> Hi,
>> 
>> Melanie's recent thread[1] on updating assets prompted me to put in 
>> writing some thoughts on this topic I've been having.
>> 
>> I'm curious whether it may be beneficial to make assets mutable. 
>> AFAIK assets are currently immutable because of a LL decisions early 
>> on to re-use one asset instance for very popular items sold 
>> no-modify. This makes sense for them because they can:
>> 
>> * clean up unused assets since they own the entire infrastructure 
>> (regions & DBs)
>> * save on space because they anticipate more identical copies rather 
>> than slightly modified copies
>> 
>> Perhaps taking the opposite approach in OpenSim would be a better fit?
>> I mean, copying assets when they are transferred between owners, and 
>> modifying them if they are modified in-world. I can see a few reasons 
>> this might be beneficial:
>> 
>> * OpenSim's databases are distributed so cleaning them (reaping dead
>> assets) is more difficult
>> * with the advent of distributed asset servers and the long-term 
>> vision of a wide open 3D Internet (like HyperGrid), when an item is 
>> transferred in-world its assets should probably be stored in that 
>> avatar's own inventory DB *anyway*
>> * disk is cheap, and I wonder which is more wasteful -- multiple 
>> copies of an asset, each differing slightly due to minor edits over 
>> time, or multiple copies of identical assets because they correspond 
>> to different objects in-world
>> 
>> I see this as a cleaner approach to assets for the future. Sure, 
>> storing duplicate identical assets in a DB can be wasteful, but this 
>> could be alleviated with hashes of the asset or whatnot (I believe 
>> this was brought up on this list before).
>> 
>> I realize this change would mean deep, possibly breaking, changes 
>> throughout the source code, would take a long time to hash out, etc. 
>> I thought I'd throw it out there anyway.
>> 
>> Your thoughts -- or perhaps clarifications on why this absolutely 
>> cannot be done -- appreciated :)
>> 
>> Thanks,
>> Mike
>> 
>> [1] https://lists.berlios.de/pipermail/opensim-dev/2008-
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