Getting ecash without an MTB account

Alan alan at
Fri Aug 15 10:42:55 PDT 1997

On Fri, 15 Aug 1997, Mike wrote:

> Jeremey Barrett wrote:
> >BTW, there are better solutions to operating without a mint account,
> >but they are not widely available yet.
> Are you referring to the receiver anonymous protocol?
> This is how I understand that protocol,
> Alice wants to receive e$1 from Bob. She creates a random number, blinds
> it, and gives the blinded number to Bob. He shows the number to the
> Mint, asking for a withdrawal of e$1 with a signature on this coin
> number. Bob gives the signed and still blinded coin to Alice. She
> unblinds it and spends it, end of story.

Actually the coin is intercepted and spent by Mallet.  Alice gets pissed
at Bob because she feels cheated by him.  She implements a blinding
protocol on him with an ice pick, as described by Dr. Thomas Dolby.
("Blinded with Ice Picks and/or Science")

> I thought that in this scenario, Bob can spend the coin before he gives
> it to Alice, so she runs the risk of receiving a coin that has already
> been spent. Is it impossible to spend a blinded coin if you can't
> unblind it? Or are you thinking of something totally different?

My understanding of the protocol is that the identity of the purchacer is
revealed only if the coin is double spent.  What prevents the person
wanting to find out the identity of Bob from just spending the cash more
than once?

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