Comment by synctext | Hacker News Reader

Comment by synctext | Hacker News Reader

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Trustchain is a ledger which is consensus-free. Forget anything you know about chains and ledgers.

By using legally valid digital signatures it is possible to sign agreements which are irrefutable. If you have two parties which sign a contract, it become legally enforceable. Trustchain requires that any block is signed by multiple parties and thus become legally enforceable. Every transaction forms its own "micro-block". Mono-signature transactions are strictly not allowed (e.g. Bitcoin,Ethereum approach). Once signatures are added to a block its valid: instant finality. Weird...

Yes, it's a strange approach, even older then Bitcoin :-) Perhaps its useful. See "bandwidth-as-a-currency" news item in BBC News, 1 Sep 2007, http://news.bbc.co.uk/2/hi/technology/6971904.stm

Edit: no native token or money creation. Its just fabric for recording transaction micro-blocks. Non-profit. So nothing like Bitcoin at all. So works very well with dApps, Distributed Apps, no smart contracts needed. Scientific publication about Euros, DAO, dApps, passport-grade identity deployment: https://dl.acm.org/doi/abs/10.1145/3428662.3429744

So is there a reason to call it “blockchain” except for marketing reasons?

(I'm currently working on a Paxos-based distributed system for an industrial application, and my client insist in calling that a “blockchain” in all internal communication because, you know “blockchain” sounds cool to them)

Distributed ledger would be a better fit indeed. However, nobody then understands what it is.

It offers tamper-proof micro-blocks, distributed validation, and leaderless governance. So this is more then idle marketing. But you're right, the name "Trustchain" is specifically tailored that government leaders and managers feel trustworthy and cool about it.

Isn't this just a digital check? People can tamper with their app and their checks will bounce once reality catches up.

Yes, you need something against tampering. However, once you legally signed something, the contract/transaction is valid.

Various mechanism can be used to ensure integrity. What we implemented specifically is that various witnesses can inspect your Trustchain blocks and co-sign your balance. So any node can act as a digital notary. You can also use a reputation or trust function.

Here is a master thesis from Mathematics on distributed accounting systems. It contains numerous new mathematical proofs around integrity without strong identity assumption; .PDF "On the Sybil-Proofness of Accounting Mechanisms in P2P Networks", https://repository.tudelft.nl/islandora/object/uuid:6b4011c6...

Problem is you cannot have offline and privacy (or better anonymity) at the same time.

Reputation and trust can be gamed. Also requiring reputation will slow down adaptation.

I will read this paper in the evening but I don't think you can have Sybil-Proof Accounting on P2P without some tradeoffs.

It would be wouldn't it?

The double spend problem is not solved.

And how could it be if it works offline. If I have a phone in some state s. Then I can just do the transaction and revert the phone's state back to s and spend the money again.

I think they solved by using a banner on the app that say "Don't do It bad boy! Or I'll say it to your mum".

Correct. The double spending is not solved technically, but critically relies on a functioning legal system.

Every time you create Euros, you simply create a negative balance. If you offline sign multiple I Owe You contracts, you accumulate debt. Just like in the real world, if you sell your house to 12 different banks, you have a (felony-level) problem. We ensure that double spending is detected with certain guarantees. Each micro-block with a transaction within Trustchain needs to be signed by two parties, so each copy is valid. Block hiding attacks wont work then.

The proof-of-work system is very elegant. The emergent properties of mining have created an amazing ecosystem. But slow finality might be a showstopper for mass uptake. Our alternative with instant finality using multiple legally binding signatures might offer a way out.

I've dreamed of something like this too. I think it fills a good spot especially smaller transactions.

I see parallels to the nordics bankid+swish, bank issued id/phone payment system. It's flawless in execution but both the id(!) and the payment part carries a cost picked up by the person accepting money (about $0.12 for each, very bank like). With your way of doing things none of the parts has to cost anything at the reasonable expense of potential double spending.

First of all, they clearly state the need for some amount of consensus here: https://tools.ietf.org/id/draft-pouwelse-trustchain-01.html#...

Second, if multiple parties are involved (I have to assume you mean more than just the needed 2 parties), wouldn't that mean you must be connected to a wider internet?

How does one rotate keys, in the event of compromise?

What's a "legally valid digital signature" in the context?

Short answer: nobody knows yet. Its taking shape.

UK minister of Digital infrastructure only some weeks ago announce their vision, far away from running code and new laws [1]. Dutch secretary-of-state on same days also send his digital ID vision to parliament [2].

[1] https://www.gov.uk/government/publications/the-uk-digital-id... [2] https://www.tweedekamer.nl/kamerstukken/brieven_regering/det...

Well, in EU, there's existing digital signature law with (working) provisions for signing legally-binding contracts digitally...

Maybe those are some new schemes under that framework?

I'm Spaniard. My national ID has a chip and I use it daily to sign documents with a card reader and a password. You can change your password at police stations that issue ID cards. The signature is legally valid.

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