From: Alan Reiner <etotheipi@gmail•com>
To: bitcoin-development@lists•sourceforge.net
Subject: Re: [Bitcoin-development] Is this a safe thing to be doing with ECC addition? (Oracle protocol)
Date: Sat, 08 Mar 2014 03:10:40 -0500 [thread overview]
Message-ID: <531AD080.40501@gmail.com> (raw)
In-Reply-To: <CA+su7OUMgeWgkMFAmmMEpW3eN=cvU47MKt51idDrmCWEiCb+VQ@mail.gmail.com>
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On 03/08/2014 01:55 AM, Edmund Edgar wrote:
> On 4 March 2014 14:07, Odinn Cyberguerrilla
> <odinn.cyberguerrilla@riseup•net
> <mailto:odinn.cyberguerrilla@riseup•net>> wrote:
>
> Nothing is safe.
>
>
> This is true. To rephrase, imagine I gave you an ECC public key
> <ed_pub>, you gave me back a public key <odinn_pub> of your own
> devising, then I paid some money to the address resulting from
> add_pubkeys(<ed_pub>,<odinn_pub>) [1]. Can anyone either:
>
> a) Think of a way that Odinn could make an <odinn_pub> such that they
> could spend the resulting money without having <ed_priv>.
> b) Opine, somewhat knowledgeably, that this probably wouldn't be an
> easy thing to do, and they wouldn't be alarmed to see people running
> software that did this kind of thing.
>
> [1] https://github.com/vbuterin/pybitcointools/blob/master/pybitcointools/main.py#L173
Consider that I see your public key <a_pub> before I create and send you
my public key <b_pub>.
I create a new keypair, <c_pub> with <c_priv> which I know (it can be
any arbitrary key pair). But I don't give you <c_pub>, I give you
<b_pub> = <c_pub> minus <a_pub> (which I can do because I've seen
<a_pub> before doing this).
Sure, I don't know the private key for <b_pub>, but it doesn't matter...
because what
<b_pub> + <a_pub> = <c_pub> (mine)
You have no way to detect this condition, because you don't know what
c_pub/c_priv I created, so you can only detect this after it's too late
(after I abuse the private key)
-Alan
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next prev parent reply other threads:[~2014-03-08 8:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-08 6:55 Edmund Edgar
2014-03-08 8:10 ` Alan Reiner [this message]
2014-03-08 8:51 ` Edmund Edgar
2014-03-08 10:37 ` Joel Kaartinen
2014-03-08 17:41 ` Adam Back
2014-03-08 18:15 ` Natanael
2014-03-08 23:13 ` Alan Reiner
2014-03-08 20:30 ` Alan Reiner
-- strict thread matches above, loose matches on Subject: below --
2014-03-04 2:59 Edmund Edgar
2014-03-04 5:07 ` Odinn Cyberguerrilla
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