Single signature for all transactions in a block?

3 messages, 31 Dec 2017. Started by CANNON.

CANNON, Bryan Bishop, rhavar

Signatures and cryptography

CANNON 31 Dec 2017, 23:39 UTC permalink original

I had a question relating to scaling and privacy enhancements. I believe that segwit combined with aggregated signatures and coinjoin can potentially achieve such. The idea is to use aggregated signatures in conjunction with coinjoin. So that all inputs of a coinjoin transaction would have a single signature vastly decreasing size while having privacy at the same time. If majority of transactions in a block did this I assume that significant more transactions could be fit into a block? However the question I have, with the extra blockspace made possible by segwit, is this extra blockspace limited to only witness data or can it be used for transaction data such as the scenario I have described here?

- -- Cannon PGP Fingerprint: 2BB5 15CD 66E7 4E28 45DC 6494 A5A2 2879 3F06 E832 Email: cannon@cannon-ciota•info

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Bryan Bishop 31 Dec 2017, 23:46 UTC in reply to CANNON permalink original

On Sun, Dec 31, 2017 at 5:39 PM, CANNON via bitcoin-dev < bitcoin-dev@lists•linuxfoundation•org> wrote:

Quoted text (10 lines)

>
> I had a question relating to scaling and privacy enhancements.
> I believe that segwit combined with aggregated signatures
> and coinjoin can potentially achieve such. The idea is to
> use aggregated signatures in conjunction with coinjoin. So
> that all inputs of a coinjoin transaction would have a single
> signature vastly decreasing size while having privacy at the
> same time. If majority of transactions in a block did this I
> assume that significant more transactions could be fit into a
> block?

Here are some resources to read regarding signature aggregation and scalability:

https://diyhpl.us/wiki/transcripts/bitcoin-core-dev-tech/2017-09-06-signature-aggregation/ https://diyhpl.us/wiki/transcripts/gmaxwell-2017-08-28-deep-dive-bitcoin-core-v0.15/#signature-aggregation https://diyhpl.us/wiki/transcripts/scalingbitcoin/milan/schnorr-signatures/ https://bitcoincore.org/en/2017/03/23/schnorr-signature-aggregation/ https://bitcointalk.org/index.php?topic=1377298.0 https://bitcoincore.org/logs/2016-05-zurich-meeting-notes.html https://github.com/sipa/secp256k1/blob/968e2f415a5e764d159ee03e95815ea11460854e/src/modules/schnorr/schnorr.md https://diyhpl.us/wiki/transcripts/2016-july-bitcoin-developers-miners-meeting/dan-boneh/

- Bryan http://heybryan.org/ 1 512 203 0507

rhavar 31 Dec 2017, 23:49 UTC in reply to CANNON permalink original

The key to understanding how it works is to stop thinking in terms of a block size limit, but rather a block weight limit. 1 byte of witness data counts as 1 weight, the rest counts for 4 weight. A block must be less than 4 million weight. There's no separate limits at all, so any saving in the witness space (e.g. through signature aggregation) is useful for both witness/non-witness data.

-Ryan

Quoted text (52 lines)

> -------- Original Message --------
> Subject: [bitcoin-dev] Single signature for all transactions in a block?
> Local Time: December 31, 2017 5:39 PM
> UTC Time: December 31, 2017 11:39 PM
> From: bitcoin-dev@lists•linuxfoundation•org
> To: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation•org>
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA512
>
> I had a question relating to scaling and privacy enhancements.
> I believe that segwit combined with aggregated signatures
> and coinjoin can potentially achieve such. The idea is to
> use aggregated signatures in conjunction with coinjoin. So
> that all inputs of a coinjoin transaction would have a single
> signature vastly decreasing size while having privacy at the
> same time. If majority of transactions in a block did this I
> assume that significant more transactions could be fit into a
> block? However the question I have, with the extra blockspace
> made possible by segwit, is this extra blockspace limited to only
> witness data or can it be used for transaction data such as the
> scenario I have described here?
>
> ---------------------------------------------------------------
>
> Cannon
> PGP Fingerprint: 2BB5 15CD 66E7 4E28 45DC 6494 A5A2 2879 3F06 E832
> Email: cannon@cannon-ciota•info
>
> NOTICE: ALL EMAIL CORRESPONDENCE NOT SIGNED/ENCRYPTED WITH PGP SHOULD
> BE CONSIDERED POTENTIALLY FORGED, AND NOT PRIVATE.
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>
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