Printing Keys and using OCR.

David Shaw dshaw at
Thu May 17 17:24:40 CEST 2007

On Thu, May 17, 2007 at 09:07:13AM -0500, Andrew Berg wrote:
> David Shaw wrote:
> > Most of the storage media in use today do not have particularly
> > good long-term (measured in years to decades) retention of data.
> > If and when the CD-R and/or tape cassette and/or hard drive the
> > secret key is stored on becomes unusable, the paper copy can be
> > used to restore the secret key. If you have the passphrase but the
> > secret key that it encrypted was on that bad CD-R, you have nothing
> >
> Aren't optical discs supposed to last for many decades if stored
> properly and almost never used?

They're certainly advertised to (I've seen some pretty incredible
claims of 100 years or more), but in practice it doesn't really work
out that way.  The manufacturing of the media, the burn quality, the
burner quality, the storage, etc, all have an impact on how long an
optical disc will last.  Some tests show that you're lucky to get 10

For paper to last 100 years is not even vaguely impressive.  Paper
regularly lasts many hundreds of years even under less than optimal

Another bonus with paper is that ink on paper is readable by humans.
Not all backup methods will be readable 50 years later, even if you
have the backup, you can't easily buy a drive to read it.  I doubt
this will happen anytime soon with CD-R as there are just so many of
them out there, but the storage industry is littered with old now-dead
ways of storing data.

I doubt I'll still be alive in 100 years - my key storage requirements
fall somewhere in between optical disc longevity and paper longevity.
I use paper because knowing that the paper will outlive me, I don't
have to worry about reburning a disc every few years.


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