[hal@finney.org: Re: [E-Lang] ERTP-aware MintMaker]

steve jenson stevej@sieve.net
Tue, 13 Feb 2001 18:42:33 -0800


hi gang,

Hal Finney asked me in private this question earlier, and I thought
it would be useful to clear up for everybody any possible confusions
about new syntax.

In fact, Hal later email'd me with his discovery of the new syntax:


First, his question:

----- Forwarded message from hal@finney.org -----

From: hal@finney.org
Date: Tue, 13 Feb 2001 15:19:03 -0800
To: stevej@sieve.net
Subject: Re: [E-Lang] ERTP-aware MintMaker

Steve - I'm afraid I don't know E very well, so I don't know if this
is a typo or what.  My first thought was that if I could get the
Incr object for my Purse, I'd be in good shape, I could add anything
I wanted to the purse's balance.  But getIncr only gives it to me
in sealed form.  Then I looked to see if I might be able to trick
something into unsealing it.  I noticed the vouch method in the
issuer does,

         to vouch(other) :any {
             unsealer unseal(other.sealed)
         }

I'm not clear what this "other.sealed" syntax means though.  I'm not
familiar with the use of dots in E.  If this were just "unsealer
unseal(other)" then I could hand it my sealed getIncr object and it back
in the clear, which would defeat the security.

I notice you use dots in a few other places, as with other.quantity.
Does this mean you can look into someone else's purse and see its
quantity variable?  I would have thought that would have to be
explicitly declared.  So maybe I'm missing something here.

Hal

----- End forwarded message -----


And now, the answer to his own question:


----- Begin forwarded message -----

From: hal@finney.org
Date: Tue, 13 Feb 2001 16:22:19 -0800
To: stevej@sieve.net
Subject: Re: [E-Lang] ERTP-aware MintMaker

Hi, I figured out what the dots are... other.sealed is like a shorthand
for "other getSealed", other.quantity is "other getQuantity" and so on.
So my idea about unsealing the Incr won't work.  I'll let you know if
I see anything else -

Hal

----- End forwarded message -----


I hope this clears up any confusion,
steve