Subject: [Bitcoin-development] ecash and revocability

From: Adam Back <[email-masked]>
Date: Tue, 14 May 2013 13:51:51 +0200

So back in 1999, in an ecash thread on cypherpunks I claimed:

http://marc.info/?l=cypherpunks&m=95280154629900&w=2

> I wouldn't say ecash has to use blinding, but I would argue it would be a
> misuse of the word "ecash", if something which was revocable were dubbed
> ecash.

This was in the context of a discussion of digigold (e-gold stored the
physical gold, digigold offered "ecash" backed in that physical gold). 
Digigold ran on Systemics payment server/sox protocol.  Because of inferred
regulatory concerns and patent licensing issues digigold & systemics were
not using blind signatures.  However with systemics sox server, like
bitcoin, you could create multiple accounts on demand and shuffle payments
around for a degree of privacy.  The bitcoin analogy would be the
transaction log lived in the systemics server, so it had a central failure
point, but arguably more privacy as the log was not public.  Also systemics
SOX protocol (Ian Grigg & Gary Howland) had some aspect of bitcoins smart
contract concepts - ricardian contracts. 
http://iang.org/papers/ricardian_contract.html 

(Btw the anonymous reply itself was interesting -
http://marc.info/?l=cypherpunks&m=95280154629912&w=2 that could have been
Nakamoto, the only missing thing from the parts on the discussion room floor
to bitcoin is mathematical inflation control.)

The thread actually started here
http://marc.info/?l=cypherpunks&m=95280154629912&w=2 and then continues here
http://marc.info/?l=cypherpunks&m=95280154629900&w=2 because of a subject
line change and then http://marc.info/?l=cypherpunks&m=95280154629916&w=2
and http://marc.info/?l=cypherpunks&m=95280154629948&w=2
more subject line change confusion.

A related thread a few days later also covers Sander & Ta-Shma (which
zerocoin is based on):

http://marc.info/?l=cypherpunks&m=95280154630167&w=2

there were many more threads about various ecash technologies.

Adam