[Cryptography] [ANNOUNCE] HashCash Digital Cash

Ashish Gulhati crypto at ashish.neomailbox.com
Thu Jun 22 16:11:07 EDT 2017


> On Jun 22, 2017, at 7:47 AM, Patrick <patrick at rayservers.net> wrote:
> 
> If the list of spent coins at one vault somehow reached unmanageable
> proportions, the issuer could possibly announce an expiration of that
> currency.  Holders of the currency would be required to trade the old
> currency for equivalent units of a new currency with a fresh history.
> The expiration could be set to occur over a reasonable time frame to
> give everyone due notice.  Eventually the record of spent coins in the
> old currency could be deleted.

Yes, a vault could declare a date when it will be switching to new keys,
and ask all coin holders to exchange their old coins for new ones by a
certain date. That would enable the vault to clear out its spent coin DB.

It would also be a good idea to keep the old spent DB around, and offer 
the service of exchanging old coins for an extended period for a higher fee, 
thereby ensuring that people who, for whatever reason, weren’t able to 
exchange their coins in time don’t lose their funds.

As a vault doesn’t know its coin holders and has no way to contact them,
there probably needs to be a mechanism in the wallet to display messages
from the vault to users when they connect to it. A vault could also declare
key changes on its website, but it can’t be sure users will be visiting the
site on a regular basis.

Given that some users may not come to know of the key change if they
don’t visit the vault’s website and don’t use the vault for a long time, 
keeping the old spent DB around for these users would be a good idea.

Alternately, a vault could also use keys that have a pre-determined
expiry date, which is disclosed to users up front when the buy their coins.
That gets around the problem of there potentially being some users who
don’t know about the key change date.

A vault might also need to change keys if there’s a weakness found in
the code, which may require new keys after being fixed.

Cheers

#!



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