From: <jl2012@xbt•hk>
To: "'Tier Nolan'" <tier.nolan@gmail•com>
Cc: bitcoin-dev@lists•linuxfoundation.org
Subject: Re: [bitcoin-dev] BIP CPRKV: Check private key verify
Date: Tue, 19 Apr 2016 03:03:07 +0800 [thread overview]
Message-ID: <00aa01d199a4$f3a41c80$daec5580$@xbt.hk> (raw)
In-Reply-To: <CAE-z3OWjqQ=UgNRXyxJiTzsW6Ze7Ytwz3kK2HYcC7eLy2jKnow@mail.gmail.com>
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I just realize that if we have OP_CAT, OP_CHECKPRIVATEKEYVERIFY (aka OP_CHECKPRIVPUBPAIR) is not needed (and is probably better for privacy)
Bob has the prikey-x for pubkey-x. Alice and Bob will agree to a random secret nonce, k. They calculate r, in the same way as signing a transaction.
The script is:
SIZE <r-length + 1> ADD <0x30> SWAP CAT <0x02|r-length|r> CAT SWAP CAT <pubkey-x> CECHKSIGVERIFY <Bob pubkey hash> CHECKSIG
To redeem, Bob has to provide:
<Bob sig> <0x02|s-length|s|sighashtype>
With k, s and sighash, Alice (and only Alice) can recover the prikey-x with the well-known k-reuse exploit
( https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm )
The script will be much cleaner if we remove the DER encoding in the next generation of CHECKSIG
The benefit is prikey-x remains a secret among Alice and Bob. If they don’t mind exposing the prikey-x, they could use r = x coordinate of pubkey-x, which means k = prikey-x (https://bitcointalk.org/index.php?topic=291092.0) This would reduce the witness size a little bit as a DUP may be used
From: bitcoin-dev-bounces@lists•linuxfoundation.org [mailto:bitcoin-dev-bounces@lists•linuxfoundation.org] On Behalf Of Tier Nolan via bitcoin-dev
Sent: Monday, 29 February, 2016 19:53
Cc: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] BIP CPRKV: Check private key verify
On Mon, Feb 29, 2016 at 10:58 AM, Mats Jerratsch <matsjj@gmail•com <mailto:matsjj@gmail•com> > wrote:
This is actually very useful for LN too, see relevant discussion here
http://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-November/011827.html
Is there much demand for trying to code up a patch to the reference client? I did a basic one, but it would need tests etc. added.
I think that segregated witness is going to be using up any potential soft-fork slot for the time being anyway.
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prev parent reply other threads:[~2016-04-18 19:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-11 20:05 Tier Nolan
2016-02-11 22:20 ` Thomas Kerin
2016-02-11 23:04 ` Tier Nolan
2016-02-12 5:02 ` jl2012
2016-02-12 10:05 ` Tier Nolan
2016-02-29 10:58 ` Mats Jerratsch
2016-02-29 11:52 ` Tier Nolan
2016-04-18 19:03 ` jl2012 [this message]
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