future proof file encryption

[David Shaw]

On Mar 2, 2009, at 9:19 AM, Mark H. Wood wrote:

> On Fri, Feb 27, 2009 at 08:37:53PM -0500, Robert J. Hansen wrote:
>> For long-term photographic storage, make a print from photographic  
>> film
>> on archival-quality print stock.  Also, I'm given to understand that
>> black and white photographs survive the aging process much better  
>> than
>> color.
>
> Silver chemistry is (or, at least, it used to be) much more resistant
> to decay than color dyes.  You still have to be sure that the print
> has been archivally processed (mainly to wash out all traces of hypo,
> which otherwise will continue doing the job it has in the process and
> eat away at the silver grains).  You still need to keep it away from
> atmospheric contaminants when not in use.  You can plate the grains
> using a bath of gold chloride to protect them a little longer.  You
> can use vesicular film rather than silver, if you can still find it,
> for even longer storage.  (Huh, *silver* chemistry is getting harder
> to find.)
>
> Used to be that color photos which had to be preserved for a long time
> were stored as separation sets:  three silver images were made to
> capture the three primary colors from the image, to be reassembled
> later and reconstitute the color image using the ordinary dye
> process.  Dunno if it's still done.

I thought it was more or less dead, but then a new company popped up  
to do silver YCM separations *generated from a digital scan*.   
(Speaking about movies here - obviously anyone can generate  
separations for stills with Photoshop or the like).  It's less crazy  
that it seems on the face of it.  The separations have longer life  
than a backup tape, and you don't need to remaster separations every  
few years.  I still think I'd regard such a thing much as I regard the  
paper key backups from paperkey: the backup of last resort.

>  I'd put my trust in a
> well-maintained redundant set of digital scans, these days.

Me too.  I think most people do, these days.  The only issue here is  
that every few years, the scanning technology improves to the point  
where re-scanning the original (chemical) image becomes worthwhile.   
So you do need to keep the original around.

> Most photos won't really need all this fancy treatment; you enjoy 'em
> while they last, and keep making new ones.  The problem is, often we
> don't understand which ones *should* have special preservation, until
> it's too late.

Indeed.  There is an interesting debate over whether digital photos  
are too easy to erase.  Every now and then, the "unimportant" photo  
turns out to be needed.  For example: http://digitaljournalist.org/issue9807/editorial.htm

David