bitfreak!



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LegendaryActivity: 1536Merit: 1000electronic [r]evolution [CLOSED] $20,000 Mini-Blockchain Implementation December 15, 2013, 02:33:09 AM

Last edit: April 25, 2014, 12:17:17 AM by bitfreak! #1 This bounty is now closed as per the last update. If you have any questions please send me a PM.

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bitfreak!



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LegendaryActivity: 1536Merit: 1000electronic [r]evolution Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 02:40:24 AM #2 Also, I feel like developers will be much more willing to work on fulfilling these bounties if I can provide some way of ensuring that they will be rewarded the bounty upon completing the task, but I'm not really sure the best way of doing that. So if you have any good ideas relating to that let me know.

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BitcoinFr34k



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Hero MemberActivity: 504Merit: 500 Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 07:17:28 AM #5



The forum has several trusted escrow members like



Hope this helps and good luck with your project. Too bad I can't code An escrow service is basically a middle man. You send them the money in advance and they will hold it until someone completes the job. Then they will transfer the money to that person. If a set date expires without someone completing the job they will transfer the money back to you.The forum has several trusted escrow members like JohnHamilton and escrow.ms . Click their names to visit their threads. You can also view their user profiles to see whst feedback they have received from previous transactions.Hope this helps and good luck with your project. Too bad I can't code

Cryddit



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LegendaryActivity: 924Merit: 1055 Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 07:33:56 AM #6 There is a bit of problem with the mini-blockchain idea as presented here.



A blockchain is secured by the work of finding preimages for hashes. That's what you need to do in order to build a blockchain from least recent to most recent. However, going the other way, you just need to start with the 'preimage' you want, plug in some arbitrarily chosen nonce, and run the hash function once. So you could fabricate a supposed 'recent' block and then, with very little effort, construct a fake chain that leads back from it -- to the full length of your mini-blockchain.



So here is the issue. An attacker can present hundreds of bogus mini-blockchains per second and the client has to figure out which one is real. In the absence of a way to check things back to the Genesis Block, that's difficult.



I'm not saying the problem isn't solvable. It's just kinda non-obvious. One thing you need to do is to make sure it's more computationally expensive to create new blocks backward than it is forward.





bitfreak!



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LegendaryActivity: 1536Merit: 1000electronic [r]evolution Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 08:15:31 AM #7 Quote from: Cryddit on December 15, 2013, 07:33:56 AM So here is the issue. An attacker can present hundreds of bogus mini-blockchains per second and the client has to figure out which one is real. In the absence of a way to check things back to the Genesis Block, that's difficult.

I'm not sure that you fully understand the concept, the mini-blockchain is exactly the same as a normal blockchain except that after a certain number of blocks the transactions are pruned from the blocks. The remaining block headers form the proof chain and the proof chain feeds into the mini-blockchain, and that makes it simple to verify the mini-blockchain against the proof chain (meaning the proof chain with the highest cumulative difficulty). You can check the proof chain all the way back the genesis block, you just cannot check the transactions all the way back the genesis block because the transactions are discarded after I certain period of time like I just mentioned. The way that address balances are maintained without a record of every transaction which ever occurred is via the Account Tree. The only attack I know which could get around the security of this design is the Secret Chain Attack documented on the Weaknesses and Attack Vectors page of the wiki. I'm not sure that you fully understand the concept, the mini-blockchain is exactly the same as a normal blockchain except that after a certain number of blocks the transactions are pruned from the blocks. The remaining block headers form the proof chain and the proof chain feeds into the mini-blockchain, and that makes it simple to verify the mini-blockchain against the proof chain (meaning the proof chain with the highest cumulative difficulty). You can check the proof chain all the way back the genesis block, you just cannot check the transactions all the way back the genesis block because the transactions are discarded after I certain period of time like I just mentioned. The way that address balances are maintained without a record of every transaction which ever occurred is via the Account Tree. The only attack I know which could get around the security of this design is the Secret Chain Attack documented on the Weaknesses and Attack Vectors page of the wiki.

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CIYAM



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LegendaryActivity: 1890Merit: 1004Ian Knowles - CIYAM Lead Developer Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 08:55:34 AM #11



If the dev fails to deliver by the date and time that they had promised to then the task can be re-opened.



This is being used for the Moneychanger project as well as for the CIYAM project itself.



Also if you need an escrow then for a small fee I'd be happy to do this (check my trust rating).

You would be welcome to create a project on CIYAM Open for this ( https://ciyam.org/open ) - it has a workflow process that locks in a chosen dev for a period of time (so no-one is wasting their efforts rushing to get a bounty) and for this project I would not charge any fee.If the dev fails to deliver by the date and time that they had promised to then the task can be re-opened.This is being used for the Moneychanger project as well as for the CIYAM project itself.Also if you need an escrow then for a small fee I'd be happy to do this (check my trust rating).



GPG Public Key | 1ciyam3htJit1feGa26p2wQ4aw6KFTejU With CIYAM anyone can create 100% generated C++ web applications in literally minutes.

BitcoinFr34k



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Hero MemberActivity: 504Merit: 500 Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 08:57:55 AM #12



He recently escrowed a 18 BTC deal, so he's experienced with larger amounts of BTC. You could send him a PM and try to figure out how you are planning on doing it. I think escrow.ms is a good choice. Here is his trust record: https://bitcointalk.org/index.php?action=trust;u=76380 He recently escrowed a 18 BTC deal, so he's experienced with larger amounts of BTC. You could send him a PM and try to figure out how you are planning on doing it.

bitfreak!



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LegendaryActivity: 1536Merit: 1000electronic [r]evolution Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 09:02:42 AM #13 Quote You would be welcome to create a project on CIYAM Open Thanks for the offer, but the problem is finding developers skilled enough to work on a project like this. That's why I created a bounty in the first place, because I found it very difficult to put together a team of developers skilled enough to work on this project. If there is a team of developers out there who think they can get the job done then I am more than willing to that route. And I will also keep your escrow offer in mind, because you strike me as some one I can trust to get the job done. Thanks for the offer, but the problem is finding developers skilled enough to work on a project like this. That's why I created a bounty in the first place, because I found it very difficult to put together a team of developers skilled enough to work on this project. If there is a team of developers out there who think they can get the job done then I am more than willing to that route. And I will also keep your escrow offer in mind, because you strike me as some one I can trust to get the job done.

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Baldassare



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MemberActivity: 68Merit: 10 Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 09:18:23 AM #14 I'm working on a similar idea, but with only two components: account tree and proof chain. Also writing in python. Project is progressing, should be done in a few month.

Not really interested in the bounty.

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MemberActivity: 68Merit: 10 Re: [BOUNTY] $20,000 Mini-Blockchain Implementation December 15, 2013, 09:32:12 AM #17 Cool, I will be watching this thread and will report if I've made any progress.

Good luck by the way. This is the right direction for altcoins to take.