What is Blockchain Architecture?

in #research6 years ago

One of the central research themes in my study of theory for Distributed Ledger Technology (DLT, or blockchains and cryptocurrencies and the like) is that of Ledger Architecture. But what do I mean by Ledger Architecture?

What is Architecture?

In my parlance, I take "architecture" to mean the high-level details surrounding the following things:

  1. Who is allowed to add things to the ledger?
  2. If two people simultaneously try to add conflicting things to the ledger, how do you decide which one belongs?
  3. How do we know that a bad guy can't re-write the ledger?

In Bitcoin and other similar proof-of-work blockchain-based cryptocurrencies, the answers are simple and relatively well-understood. I call this the "architecture" of bitcoin:

  1. If you solve a proof-of-work, you're allowed to add any valid transactions you want to the ledger all bundled together in a block.
  2. In deciding between two blockchains, the longer one is considered valid. That is, if two miners try to add blocks simultaneously, then the chain temporarily "forks" -- this fork is not resolved until a future miner builds on one of the forks. As soon as this happens, the longer fork wins.
  3. If a bad guy has less than 50% of the hash power of the mining network, then the probability that the attacker can reverse a transaction decays exponentially with time. That is, the longer we wait, the safer the transaction is.

What other architectures are there?

Not everybody believes that Bitcoin has the best architecture, and many people are actively searching for something better. I started to piece together my thoughts on this topic recently when I started looking into the IOTA cryptocurrency. Without going into a great deal of detail, IOTA is a cryptocurrency that works somewhat differently than Bitcoin (or Steem). In particular, IOTA has no blockchain. The IOTA Foundation claims that this allows IOTA to do things that Bitcoin can't. Because I'm a curious kind of a person, as soon as I started reading this I set out to try to understand whether this is actually true.

How might we answer the above questions for IOTA?

  1. Anybody, anywhere is allowed to add a transaction to the ledger -- the only rules are that you have to do a small proof-of-work, and your transaction has to reference two other valid transactions that are already in the ledger.
  2. Just like in Bitcoin, we wait to see which of the conflicting things "wins" in the long run. Unlike Bitcoin, there is no sharp rule for deciding which of the conflicting transactions wins; we just do it probabilistically based on some formulas.
  3. The IOTA Foundation claims that if a bad guy has less than 33% of the hash power of the network, then the probability that the bad guy can reverse a transaction decays with time. I am not aware of any formal proof of this.

So it's all quite a bit different in IOTA from how it works in Bitcoin, but if we can model both using the same mathematical tools (that is, by formally answering each of the above 3 questions), then we can actually compare the two systems in a formal way. We might then notice things like this:

In IOTA, security is determined by hash power, and hash power is provided by users. It seems reasonable to conclude that total security is proportional to transaction volume. This is fundamentally different from Bitcoin; in which the hash power is somewhat more independent of the transaction volume on the network. In IOTA, if the transaction volume suddenly drops, it appears that the network instantly becomes more vulnerable to attacks. In Bitcoin, a decrease in transaction volume would likely have a much smaller effect.

So what questions will I ask with this framework?

  1. Does a cryptocurrency need a blockchain, or is IOTA's "Tangle" just fine?
  2. What are the consequences of separating users from block producers? Does Bitcoin
  3. What are the fundamental limitations to secure transaction rates?
  4. Are the IOTA Foundation's claims that "the network gets faster the more it is used" correct?
  5. Why do Graphene-based DPOS chains apparently perform so much better than PoW mining chains? Has something important been lost, or are they just better?

Stay tuned for more of my quick thoughts on DLT Theory!

If you want to partner with me to define the questions, find the answers, or fund those of us who do, please reply here and join the conversation. I'm beginning as a tenure-track professor of Computer Science at the University of Colorado, Colorado Springs in August, so I'm always on the lookout for motivated graduate students (get paid to get a PhD in computer science in beautiful Colorado Springs!) and funding partners.


Just a side comment... I never understood why people have these tendencies of creating new acronyms for everything. As an example, "DLT, the International Conference on Developments in Language Theory is an academic conference in the field of computer science held annually under the auspices of the European Association for Theoretical Computer Science"

For me it's about two things: shortening and branding. I use DLT because it's a nice quick abbreviation for a very big concept. I'd say blockchain, but a blockchain is only one way to implement a DLT.

DLT was neccessary, so that IBM with Hyperledger also can playing on the market. Because a decentralized database could not sell as Blockchain Technology only as DLT ...


I've just had a couple of really welcome @ gentlebot comments in 2 days. I had no idea who @ gentlebot was so I read up and here I am.
I simply wanted to say thank you :-)

You're very welcome!

Great post!! Very informative! I'm going to show this to my family member who is having a hard time grasping the concept. I learned a lot, I know he will too! (^_^)

I wish I had that math skill to join your PHD program lol. Thanks for explanation about IOTA, I hope you will also talk about Cloud Coin.

I haven't heard of cloud coin. Is it another of these blockchainless ones?

Yea, kind of, here is founder interviewed by Connie:

I spent a little bit browsing around their website, and I can say confidently that I'm not going to buy cloudcoin until they offer some evidence that the RAIDA is a real thing that actually exists in the world.

Thanks for your time and the feedback, I appreciate that. 👍

Hi. Now we have new platform: Steem Monsters. https://steemmonsters.com I would say it is interesting enough, many people are addicted. Kindly give some review please. Thx

Yeah, I came across that the other day. I certainly like the look of it! When I looked at it a couple weeks ago it didn't seem like there was much to review yet. Have they started doing anything other than just selling cards?

No they haven't :)

Simple put Blockchain Architecture has to do with planning for the possible action and outcomes that can happen on the blockchain and it can be handled.

@biophil we are finding that @gentlebot is upvoting many spam and copy/paste comments. Could you please come by our discord to chat with us?

Maybe I let your invite expire, but it's not letting me through.

I've seen a lot of that spam and stuff that gentlebot is voting on. There are some more foundational issues that I need to address with his algorithm, but for now I've put in some basic protections that should hopefully shut some of it down.

Looks like there are only @pocketjs @pocket-pi and maybe @pocket-node left on the network.

Yes it is. I’ve just resumed development for it and completed the replay from genesis /zero.

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