Topic: Qubic - Quorum-Based Coin - page 6. (Read 25283 times)

Is there more to the 'network-bound proof-of-work' other than ip addresses?

I assume if you call it 'proof-of-work' there must be more than unique ip addresses? Number of transactions received?

Can't say for sure if you have at least mitigated sybil attack with just the sketch you provided but Etlase has some good points here.

Also the inflation model seems to be wide open.

You claim a sybil attack can't be mounted easily, but the only defense you seem to have is that honest people will have more. One botnet could have thousands or hundreds of thousands of IP addresses. Once IPv6 is the norm, governments and ISPs will have easy access to billions of IP addresses. The trust system might work among providers that know and trust each other, but this does nothing for people trying to use the network. They will be inundated with all kinds of providers and have no clue as to which ones are trustworthy. Not to mention since each provider will likely have a different idea about who is trustworthy, trust can't be used to weigh votes on how many coins are created. So someone with tens of thousands of IPs can just say "I want 9999999" tens of thousands of times (good lord the data consumption) and destroy any value to the currency.

you gotta solve this too: http://en.wikipedia.org/wiki/Byzantine_generals

You might be interested in this: https://github.com/FellowTraveler/Open-Transactions/wiki

Minting algo can be adjusted. Or completely changed. And then we'll see if it works.

It's not necessary to choose whom to trust when there are thousands providers and Sybil attack can't be implemented easily. At early stage with a few providers only small amount of qubics can be minted and it's easy to audit every qubic. Real qubics can be minted starting from the point when the network will have enough providers to overcome attackers.

You've got a lot of work ahead of you if you think this can be used as a way to bring consensus. In a decentralized system, there has to be a way for everyone to eventually come to an agreement on what has happened.


No one else knows this information including people who want to transact on the network. Determining who to trust will be impossible and sybil attacks will be easy.

Any provider can consider any other provider to be trusted with some weight. 1000x, for example, means that an attacker has to create at least 1000 faked providers visible to the attacked provider to make a successfull Sybil attack (not all providers are visible to the others, so practically it is necessary to have more than 1000 faked ones). All data received from such a trusted provider should be carefully logged and audited (to prevent qubics to be minted out of thin air), but it is necessary only in the beginning. When more providers join the Qubic network, Sybil attack will become less dangerous. So after a while it can be possible to get rid of all trusted providers. As every provider itself marks other providers trusted and choses appropriate weights and noone else knows this information, Sybil attack doesn't seem to be an issue. Anyway I'm concerned about it and plan to simulate such kind of attack during pre-launch tests.

Everytime when a new transaction appears (SPLIT, COMBINE, REFRESH) providers distribute it each to other. When a provider receives a new transaction it increases the rating of the provider the transaction was received from. Periodically every provider asks the others if they wish to mint new qubics and receives public keys of these qubics. There are 19 keys for qubics with values of 0.000000001, 0.000000009, 0.00000009, 0.0000009, ..., 0.9, 9, 90, ..., 900000000 are published by every asked provider. Every provider makes decision what total value of qubics it lets to be minted by every other provider and this is based on the rating.

Let's imagine that provider A lets 100 QBC to be minted by provider Z. Provider B lets 10 QBC by Z and provider C - 10 QBC by Z as well. A stores qubics with keys corresponding to values 90, 9, 0.9, 0.09, ... (total = 100 QBC). B and C store keys corresponding to values 9, 0.9, 0.09, ... (total = 10 QBC) both. Now if Z try to do anything with qubics with values higher than 90 QBC it will be rejected by everyone. Transactions with 90 QBC will be accepted only by 1 of 3 providers (no quorum) so it means that the qubic [90 QBC] wasn't minted. Transactions with 9 QBC and less will be accepted by the quorum of providers.

There could be a situation when every provider refuses to accept qubics minted by the others. In this case the Qubic network will start to lose its providers (no point to work for free) and credibility of the rest of the world. So the price of 1 QBC will go down which will lower profits of remaining providers. Similar scenario is expected even in case when values of minted qubics are higher than zero but still too low. On the other hand it's undesirable for the network to mint a lot of qubics, coz in this case due to inflation the price of 1 QBC will go down as well. I suppose that the whole system will find a point of dynamic balance, just like the market does.

The same with already existing qubics. It's necessary to ask some providers if this particular qubic exists. If u asked 100 providers and more than 50 said "yes", than u should consider it's legit qubic. If u r not satisfied with numbers than just ask 1000 providers and keep asking as long as u wish.

Bitcoin has accounts and their balances. Qubic doesn't have accounts. Qubics are very similar to real coins as there are no connections between a purse (a wallet in Bitcoin) and a qubic.

Something within 60 seconds. Need to make experiments though as this depends on an implementation.

From what I gather this is somewhat based off of the Chaumian-style digital cash.

1. How does the system prevent sybil attacks without proof of work?
2. How is consensus reached on how many and what coins exist?
3. What the hell does "Coins "look" like real coins" mean?
4. How long do you expect it to take consensus to be reached to prevent double spending?

Here is a re-post from http://qubic.boards.net/

What Qubic is
Qubic is a medium of exchange in the Information Age. It is money that can be created, controlled and used by anyone.

Why Qubic was invented
Inspired by Bitcoin and its forks, the author of Qubic began to think of a currency that would have advantages of Bitcoin but would not have its disadvantages. After a while he came to a concept that was named "Qubic".

Where name "Qubic" came from
An idea of quorum-based coins is the core of the concept. These coins are created and controlled by arbitrary nodes on the Internet without any central authority. Name "Qubic" came from acronym "QBC" which stands for "Quorum-Based Coin". The coins are called "qubics" to distinguish them among other types of coins.

What qubics are
Qubics are binary data stored in computers. These data contain information about value of qubics, their public and private keys. A private key is known only to a qubic's owner and is used to prove ownership.

How qubics are created
Qubics are created ("minted") by nodes ("providers") that run special software. Every provider does work necessary for normal existence of the Qubic network. Periodically every provider receives new qubics as a reward for its support of the network and this reward is proportional to quality of provided service.

What service is provided
Providers mint new qubics. They let qubics to be split, combined and refreshed, providers also prevent double-spending of qubics. Splitting is used to split a qubic to ones with lesser values to get specific amount. Combining is used to combine qubics to make them easier to store. Refreshing is used to change private keys, it is also used to stress-test the network to keep it healthy.

How qubics are transferred
To transfer qubics during a trade between parties it is necessary to transfer private keys. After the keys are accepted by the seller the qubics are destroyed and new ones with the same values are created. Private keys of the new qubics are known only to the new owner. Transfer of keys occurs outside the Qubic network (via e-mail or special software), so it is impossible to track transactions made with qubics. Destroying of qubics and creation of new ones is a common occurrence and noone can prove that this happened due to a trade.

What features Qubic has
- Value of a qubic varies from 0.000000001 (10^-9) to 999999999.999999999 (almost 10⁹), it is 9 decimal places before and after the point.
- Supply of qubics is theoretically unlimited. Every provider decides how many qubics it lets to be rewarded to the other providers. In the future the system can come to a state when total value of minted qubics becomes less than total value of qubics lost during the same period of time. (Some loss of qubics is expected due to lost keys and other causes.)
- No fees are supposed to be charged for transactions as they occur outside the Qubic network. Providers obtain qubics by providing the service.
- Transactions can not be tracked.
- Noone needs to reveal theirs real identities to be able to use Qubic.
- There are no "accounts" in Qubic, only "coins" which can be lost but can not be nullified.

Implementation of the concept
The author is working on an implementation of the concept. Constructive suggestions and help in testing are very welcome.

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Quick comparison with Bitcoin:

- No fees
- Transactions can't be scrutinized
- Network-bound proof-of-work instead of CPU-bound one is used
- New coins are produced at the rate determined by quorum of miners, not by developers (good ole Greek democracy)
- Coins "look" like real coins (not a ground-breaking feature but a neat one)
- No need to download gigs of data from "a blockchain", every miner is allowed to handle only fraction of the Qubic network
- Transfer of money in Qubic is supposed to be much faster than in Bitcoin
- Qubic is more eco-friendly as it doesn't require a lot of electricity to be spent
- (I'll add more if anything comes to mind)