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Re-Launching The Borderless, Unkillable Crypto-Fiat Gateway, DAIHard. Enter or Exit Crypto via Any Fiat and Any Payment Method, Anywhere in the World, Without KYC. All you need is a little Dai.
Some of you might recall recall our initial facepalm failed launch about 3 months ago (post-mortem here). Well, we're back--this time with an audit and some new features. This version of DAIHard should should die a little harder this time ;)
After shopping around a bit in the auditor space, we decided to go with Adam Dossa--the very same Adam Dossa that actually found our launch vulnerability and responsibly disclosed it to us! You can see his report here. By the way, Adam has been a gem: friendly, professional, timely, and flexible. Definitely keep him in mind if you need an audit!
Following is an updated version of our original launch post. If you've already read that, you might want to skip to the heading What's New in v0.9.2. Or you can go straight to the app or go to our info site for more info! Here is a legitimate concern most of us are familiar with:
To enter or exit the crypto economy, we rely on centralized exchanges such as Coinbase, which track their users, impose limits, and are tightly coupled to their jurisdiction and its banking system. And for all we know, any day now regulations could start tightening these controls further (*we've actually seen some of this play out in the two months since our first launch post). In light of this, can we say in any meaningful sense that crypto is anonymous, limtiless, borderless, immune to regulation, and (most importantly) unstoppable?
To really address this concern, we need a completely decentralized gateway between fiat and crypto: something that extends the benefits of crypto to the very act of moving between the old and new economies. But the design of such a platform is far from obvious. (Localethereum comes close, but as discussed under Unkillable, it doesn't quite cut it. And Bisq is decentralized, but has significant UX hurdles.) We believe we've found a solution. We are proud to present:
DAIHard v0.9.2 - Almost Definitely Not Broken This Time
If you want to jump right in, we recommend first watching our latest usage demo (7 min), then diving in and giving it a shot with a small amount of Dai. (Try it on Kovan first if mainnet is too scary!) DAIHard extends many of the promises of crypto (borderless, anonymous, limitless, unstoppable) into the exchange mechanism itself, allowing anyone, anywhere to bypass centralized exchanges and the control they impose. More concretely, DAIHard is a platform, run on smart contracts, for forming one-off crypto/fiat exchanges with other users, in which:
The method of fiat transfer is open-ended, but agreed upon up-front (for example: bank transfer, cash handoff, transfer of online credit, cash drop...).
You and the counterparty can communicate via end-to-end encrypted chat to coordinate the fiat transfer (i.e. communicate bank account number or reveal a cash drop location).
Crucially, in the last phase, the Seller can choose to burn the Dai instead of releasing it to the Buyer (but he can't get it back). This credible threat of burn is what makes the platform reliable in the absence of a centralized group of arbitrators or moderators. For more on this see the DAIHard Game Theory medium article (10 min read).
You Need either xDai, or both Dai and Ether, to Use The Tool (At Least For Now)
If you want to buy Dai on DAIHard, you must already have Dai--1/3 of the amount you want to purchase--to put up as a burnable deposit. For example, if you only have 10 Dai now, you can only commit to buying 30 Dai, and must complete that trade before using the newly bought Dai to open up a bigger offer (for up to 120 Dai that time). Most tragically of course, this means that if you don't already have some crypto, you can't use this tool to get crypto--this is why we avoid calling DAIHard an onramp specifically. This comes from the fact that both parties must have "skin in the game" for the game theory to work, and a smart contract can only threaten to burn crypto. We have some ideas on how to address this drawback in the not-too-distant future, which we'll write about soon. For now it's time to launch this thing and get some users!
Dangerous and Scary To Use
In rare cases, a user may have to burn Dai and face a loss on the entire trade amount. The necessity of this ever-present risk is explained in detail in DAIHard Game Theory. However, a cautious, rational user can gather information (possibly via our [subreddit](daihard)!) about how people have used the tool, successfully and unsuccessfully. They can then create a buy or sell offer with wisely chosen settings based on what has worked for others. Other cautious, rational users can find this offer and commit to the trade if they dare. We expect the vast majority of committed trades should involve rational, cautious users, and should therefore resolve happily. Still, inevitably there will be sloppy trades that result in burns. As the tool is used, we'll be keeping a close eye on the frequency of burns and keeping you guys updated (perhaps via a "System Status" utility similar to the one found on MakerDao's explorer). In the end, though, we expect the risk in using DAIHard to be comparable to the risk of using any exchange or DNM: ever-present but low enough for the platform to be useful as whole. So, while DAIHard will never shut down and can't perform an exit scam, the bad news is it's not risk-free. Users will have to approach DAIhard with the same level of caution they would with any new exchange (albeit for different reasons and with a different approach). So what's the good news?
The Good News
While these drawbacks are significant, they enable some remarkable features that no other crypto/fiat exchange mechanism can boast.
(Correction: Bisq seems to have a decentralized arbitration system) We are aware of no other crypto/fiat exchange platform that is truly unkillable. Bisq and localethereum comes close, but both localethereum relies on centralized processes of arbitration. This means their fraud-and-scam-prevention system can be sued, jailed, or otherwise harrassed--and if that part stops working, it doesn't matter how decentralized the rest of the system was. DAIHard, in contrast, gives the users the power to police and punish each other, via the aforementioned credible threat of burn. This is simple game theory, and the rules of this game are etched permanently into the DAIHard Factory and Trade contract code: impervious to litigation, regulation, and political pressure. This Factory contract has no owner and no suicide or pause code. It cannot be stopped by us or anyone else. Like Toastycoin, this thing was immortal the moment it was deployed (even more immortal than RadarRelay, for example, which does rely on an ownership role). Both DAIHard and Toastycoin (and probably whatever we build next) will last for as long as a single Ethereum node continues mining, and it will remain easy to use as long as someone can find the HTML/JS front-end and a web3 wallet. (The HTML/JS front-end (built in Elm, by the way, with the lovely elm-ethereum!) is currently hosted on Github pages, which is centralized--but even if Github takes down the page and deletes the code, it's a minor step to get the page hosted on IPFS, something that is on our near-term roadmap in any case)
No KYC, No Limits
It's smart contracts all the way down, so DAIHard never asks any nosy questions--if you have Metamask or some other web3 wallet installed and set up, with some ETH and Dai (or just xDai), you can immediately open or commit to a trade. You don't even need a username! (In fact, we're so inclusive, even machines are allowed--no CAPTCHA here!) You're limited only by the collateral you put up, so if you have 10,000 Dai you could open up a buy offer for 30,000 Dai (or a sell offer for 10,000 Dai) right now. We do reccommend trying the tool out first with a small amount of Dai... But we're not your mom! Do what you want!
It simply doesn't matter where you are, because DAIHard doesn't need to interface with any particular jurisdiction or payment system to work. DIAHard works by incentivizing people (or robots?) to navigate the particular real-world hurdles of bank transfers, cash drops, or other fiat transfer methods. These incentives work whether you're in America, Zimbabwe, or the Atlantic; they work whether the fiat is USD, EUR, ZAR, seashells, or Rai Stones; and they work whether your counterparty is a human, an organization, a script, or a particularly intelligent dog with Internet access.
Any Fiat Type, and Highly Customizeable
Here are some examples of the types of trades you might create or find on DAIHard.
Sell 5 xDai for $5 USD, sent via TransferWise.
Sell 200 Dai for $180 USD, granted they bring the cash to you by tomorrow afternoon in Central Park, NYC.
Buy 20 Dai with a $30 gift card for Amazon AWS that you were never going to use.
Sell 20 Dai in exchange for a $20 Steam game.
While in Vietnam, sell 200 Dai to someone for €180 anytime in the next two weeks, provided they deposit it into your German bank account.
While in Germany, sell 20 Dai to someone in exchange for them refilling your pre-paid Vietnamese phone plan.
Buy 500 Dai for $550 via PayPal, but wait 3 weeks for before the Dai is released (so the paypal transaction can't be reversed).
As the DAIHard community grows, users will doubtless find much more creative ways to use the system, and we will discover together which types of trades are reliable and which are more risky. Because users can set their own prices and phase timeout settings, we expect the risky trades to charge a premium or have longer time windows, while the reliable ones rapidly multiply at close to a 1:1 price ratio, with quick turnaround times.
Extensible (with profit) by Third Parties
Not satisfied with our interface? Do you have some nifty idea for how to display and organize user reputation? Or maybe some idea for how trades could be chained togeher? Maybe you'd like to design a notification system for DAIHard? Maybe you just want a different color scheme! Well, you won't need our permission to do any of this. Any tool that watches the same Factory contract will share the pool of trades, regardless of which tool actually creates the trade. This means we don't even have to fight over network effects! And if you look closely at our fee structure, you might notice that only half of the 1% DAIHard fee is "hardcoded" into the Factory contract. The other half is set and charged by our interface. What does this mean for you? If you go out and make a better interface, you can essentially replace half of our 1% fee with your own fee--it's up to you whether it's smaller or larger than the replaced 0.5%. The reason for this is to explicitly welcome other developers to extend what we've built. For as long as our team is the only one improving the platform, a threat to us is a threat to future upgrades. But if others begin extending the DAIHard platform too, then DAIHard will not only be unstoppable as it is today, but also grow unstoppably.
(For Real This Time) This Is a Big Fucking Deal
DAIHard is a turning point in crypto and a breakthrough in decentralized markets, and is an irreversible augmentation of the Ethereum platform. What we've built is a gateway to crypto completely devoid of centralized components--rendering entry and exit to crypto unkillable, flexible, borderless, and private. Centralized exchanges, and the control they impose, can now be bypassed by anyone with Dai and a web3 wallet.
What's New in v0.9.2
There have been many changes made since our first failed launch, but there are two rather important ones: xDai support and reputation tools.
DAIHard is now operational on xDai, a sidechain whose native token (xDai) is pegged to the Dai (and therefore $1). Add the xDai network to your Metamask (or just install Nifty Wallet), then switch to the xDai network in your wallet, to try it out. xDai has some pretty incredible benefits, compared to vanilla Ethereum:
Price: On xDai, a single DAIHard trade costs on the order of $0.01 to run start-to-finish, rather than the accumulated $2.40 (with the best-case-scenario 1gwei gas price) you'll spend on vanilla Ethereum.
Speed: Trade actions mine much faster, and don't require ERC20 'approve' transactions, making the whole process way snappier.
Gas priced in xDai: the main benefit here is that you only need one token (xDai) rather than two (Dai and Eth). Also, it's just nice having the gas cost expressed in (essentially) USD!
We now have a few reputation tools. First, on any open trade, there is a widget showing the number of releases, aborts, and burns the given address has been involved in as that role (buyer or seller). Clicking on this expands the widget to show more detailed information, and also provides a link to a page that lists each trade this user has been or is involved in.
We have tons of ideas on how to improve the product--too many, in fact, to commit to any before we get a good chunk of user feedback. Here are some of our favorite ideas:
A "QuickTrade" page, offering Trade Templates as an alternative to the current Create Offer page.
Big Exciting Features
Bootstrapping people with no DAI via other mechanisms and community outreach.
Partial commits to trades. eg. Place a 10,000 DAI trade and allow it to be picked up in blocks larger than 500 DAI at a time.
More chains, get this thing working on Bitcoin via Rootstock, on Ethereum Classic and Binance Chain.
A lot of the above features will be prioritized more clearly as we get user feedback, and we will be posting fairly frequent updates and articles on our info site. If you don't want to miss anything, note the subscribe widget and sign up!
The choice of the optimalways to buy Bitcoindepends on three factors: how much information you want to disclose, what is the amount of the transaction and what level of security you require. However, it is almost impossible to comply with all 3 factors. So,what is the best way to buy Bitcoin?
1. Stock exchange
The best way to buycrypto is to use an exchange (Binance, Coinbase Pro, Huobi Global), where one can sell and buy digital currency from other investors. The price is set manually. In this case, the commission charged by the intermediary will not exceed 1%. The exchange provides anonymity since you don’t need to provide your ID in most exchanges. There are several options for transactions:
Quick deal – immediate purchase or sale of currency from another exchange user;
Offer – the seller determines the conditions under which the transaction should be arranged, and the buyer can either agree with the conditions or refuse to buy from this seller;
Automatic order – the system completes the transaction when conditions are fulfilled (provided that you have the funds necessary to fulfill).
If you want to know how to begin investing in Bitcoin, start studying stock exchanges.
Fair rates. You buy Bitcoin, not at the rate that the exchanger came up with, but at the real market rate, which is constantly changing;
Safety. Trusted, reliable exchanges do not cheat. The trust of users is important to them since they earn a commission from trading;
Multicurrency. You can exchange fiat for Bitcoin, buy any other coins available, and withdraw them to your wallet.
Registration needed. Almost all exchanges require registration and request minimal personal data;
Safety. New exchanges without valuable reputation are sometimes hacked. History knows cases when the administration of exchanges defrauded users and walked off into the sunset. For example, the case of BTC-E (WEX.NZ). This is extremely rare and, as a rule, does not apply to large reliable sites. It is best not to store cryptocurrency on exchanges for the long term and to check all the information about exchanges carefully.
A crypto exchanger (Localbitcoins, Lykke, F-change) allows exchanging fiat or other tokens for BTC according to a fixed rate. It is probably the easiest way to buy crypto. The service adds a commission higher than that on the stock exchange.
Simple interface. Even a beginner will understand it;
The ability to buy Bitcoin for almost any existing currency in the world;
Anonymity. Although it depends on the exchanger and payment method, many exchangers are not interested in your personal data.
Slow speed. Sometimes the exchange may freeze for several hours;
Exchange rate. As a rule, in exchangers, the rate is not the most profitable one. It differs from the mid-market not in your favor;
Anonymity. Sometimes there were cases when exchangers leaked information about customers not to authorities, but other interested parties;
Chance of fraud. Especially, if you use an unknown site.
3. ATMs for BTC
ATMs for Bitcoins only enter the market. It is enough to have the necessary amount of cash to be able to exchange it for the equivalent in BTC. Such a transaction is instant and does not require registration or other formalities. There are now over 8500 BTC ATMs around the world.
4. For cash with individuals
A hand-to-hand sale is the most private and most insecure way to buy cryptocurrency. It is lucky if you know reliable miners or crypto businessmen. Rent, salary, taxes – all this requires ordinary money, so they constantly have a need to sell mined or earned cryptocurrency. Pros – maximum anonymity of transactions. Cons – risks from dishonest partners.
5. Telegram bots
Telegram bot is an automatic script based on the search for offers and counteroffers. If someone wants to sell BTC, they send a request to the bot and it looks for a counter offer. As soon as someone sends a request for the purchase of Bitcoin, the bot will complete a transaction between these two users.
Speed. Exchange occurs instantly. This is probably the fastest way to trade Bitcoin.
Low security. A bot can stop working unexpectedly, money can be “lost", etc. It is very difficult to bring the service to justice if something goes wrong, and you rely entirely on the decency of the bot owners;
Inconvenient BTC rate. No bidding. You are forced to work at the rate that the service states.
While talking about the ways to buy Bitcoin, it is important to mention that this article doesn’t provide any advice and directions regarding the investments in particular cryptocurrencies and pursues only informative purposes.
Ferrum Network Community Update — December 8, 2019
Dear Community, What an exciting and jammed pack few weeks it has been — with the launch of staking, the 2Key Network partnership, and a major Kudi update — to name a few! But as the profile of Ferrum continues to grow, it is essential we never stray from the fundamentals that got us this far: hard work, transparency, and a commitment to community. In this community update, we provide a recap of the last few weeks, and look ahead to a few initiatives we are planning. Business Update With the release of the FRM Flexible Staking platform, we took that opportunity to kick the marketing into high gear. These marketing efforts paid off, and we were fortunate to be picked up by top influencers like Teh Moonwalker, Oddgems, and Micro Cap Gems. Here’s what happened the past few weeks.
Released FRM Staking version 0.1 with the 18 month staking pool selling out in about 15 minutes. The total amount of FRM locked for staking is 8,412,666 + 2,397,260 locked for rewards, which equate to around 10% of FRM circulating supply.
Conducted no less than 10 AMAs in the past 4 weeks in major channels like Moonwalker’s, the AMA Room and CryptoCabital, among many others.
Announced a partnership with 2Key Network to utilize their Smart Links technology so our community can be rewarded for referring Ferrum Network products.
We’ve also seen strong growth of the Social Mining platform, with over 50 members now actively participating in the community created Social Mining Chat, and no less than 3,083 members signed up for social mining.
Tech Update For those who missed the Tech Update from our CEO Naiem Yeganeh, PhD, here are some highlights:
Backend. we have made major progress in the backend which is enabling us to launch products faster and cheaper, such as building abstraction layers around security and chain access to speed up the development process
Coding. The dev team have been working on more than 25 repositories and has averaged around 1.5 commits per day, including weekends.
Products. In the past 3 months we have built several products including KYC collection, management tools, and the Token Bridge. Last product is our staking platform built on top of Ethereum network, which is a flexible staking system for ERC20 tokens and a MetaMask integrated UI.
First Kudi. Significant progress in improving, refactoring, and adding features including one-click bank accounts, POS improvements, automatic invoicing, and more.
Unifyre Wallet: Backend is mostly complete, and we are working very hard to make it ready for Beta testers by end of year. Unifyre will be a unique multi-chain crypto wallet. It will be the first wallet where you completely take control of your private keys, but can benefit from server side security checks such as two factor authentication, AI based fraud detection, geo-fencing, locking account on a lost or stolen phone, and other security features. You will have access to buy crypto around the world and will work seamlessly with other Ferrum products.
Network and other products: Most work on Unifyre and Kudi are architectured in such a way to optimize code re-usability. We are making progress toward some other products and the mainnet, which will be announced accordingly.
First Kudi Update The First Kudi team on the ground in Nigeria continues to make significant progress.
Announced the new First Kudi website along with the upcoming initiative with the Kudi Bank card
Added a major feature to the app which gives all our users their own personal bank account through our partnership with Providus Bank!
Our Referral Program has seen major growth, with nearly 100 users being referred in the past few weeks and growing daily!
Apple iOS has been preliminarily approved! However, Apple is requesting certain accommodations so the app works on the iPad, which may require more development work. We appreciate your patience.
We released an early version of a video showing merchants using the app. More videos will be released soon.
What’s Next It is critical we capitalize on the attention we have garnered from the team and community efforts, and to start 2020 with a bang. Here are some of the upcoming initiatives we are working on. Flexible ERC-20 Staking v0.2 We are strongly considering launching another round of staking. We are taking the lessons learned from the first round and improving the experience. Community feedback will be key to make version two even better, so expect to see a series of polls in the coming days. A Trading Community A strong group of FRM traders who post technical analysis on social media is great for exposure and great for liquidity. We are currently laying the groundwork to build a trading community to come up with initiatives like trading competitions and special trading rewards. Anyone interested in joining such a community should PM Ian on Telegram. FRM on Kudi We have been working hard to add FRM and ETH to the Kudi app so our users can buy it directly with Naira. This will also open up additional utilities for the FRM token, including a premium membership program that will reward users for holding the token and using the app. More details to follow. Expansion into other Markets As you may know, one part of our business model is to partner with top notch teams in emerging markets where our fiat gateway + payments app technology can be successful. We are happy to report that we have started to work with such a team in Brazil and they are in the early stages of launching their own product powered by Ferrum Network. More news to follow. Conclusion Thank you all for your continued support of Ferrum Network. 2019 was a really special year that we will never forget. But together we can make 2020 even better! Very truly yours, The Ferrum Network Team Ferrum Network Links: Website: https://ferrum.network/ Telegram: http://telegram.ferrum.network Twitter: http://twitter.ferrum.network LinkedIn: http://linkedin.ferrum.network YouTube: http://youtube.ferrum.network Reddit: http://reddit.ferrum.network Bitcoin Talk: http://bitcointalk.ferrum.network Facebook: http://facebook.ferrum.network Github: https://github.com/ferrumnet/ Instagram: http://instagram.ferrum.network
Technical: A Brief History of Payment Channels: from Satoshi to Lightning Network
Who cares about political tweets from some random country's president when payment channels are a much more interesting and are actually capable of carrying value? So let's have a short history of various payment channel techs!
Generation 0: Satoshi's Broken nSequence Channels
Because Satoshi's Vision included payment channels, except his implementation sucked so hard we had to go fix it and added RBF as a by-product. Originally, the plan for nSequence was that mempools would replace any transaction spending certain inputs with another transaction spending the same inputs, but only if the nSequence field of the replacement was larger. Since 0xFFFFFFFF was the highest value that nSequence could get, this would mark a transaction as "final" and not replaceable on the mempool anymore. In fact, this "nSequence channel" I will describe is the reason why we have this weird rule about nLockTime and nSequence. nLockTime actually only works if nSequence is not 0xFFFFFFFF i.e. final. If nSequence is 0xFFFFFFFF then nLockTime is ignored, because this if the "final" version of the transaction. So what you'd do would be something like this:
You go to a bar and promise the bartender to pay by the time the bar closes. Because this is the Bitcoin universe, time is measured in blockheight, so the closing time of the bar is indicated as some future blockheight.
For your first drink, you'd make a transaction paying to the bartender for that drink, paying from some coins you have. The transaction has an nLockTime equal to the closing time of the bar, and a starting nSequence of 0. You hand over the transaction and the bartender hands you your drink.
For your succeeding drink, you'd remake the same transaction, adding the payment for that drink to the transaction output that goes to the bartender (so that output keeps getting larger, by the amount of payment), and having an nSequence that is one higher than the previous one.
Eventually you have to stop drinking. It comes down to one of two possibilities:
You drink until the bar closes. Since it is now the nLockTime indicated in the transaction, the bartender is able to broadcast the latest transaction and tells the bouncers to kick you out of the bar.
You wisely consider the state of your liver. So you re-sign the last transaction with a "final" nSequence of 0xFFFFFFFF i.e. the maximum possible value it can have. This allows the bartender to get his or her funds immediately (nLockTime is ignored if nSequence is 0xFFFFFFFF), so he or she tells the bouncers to let you out of the bar.
Now that of course is a payment channel. Individual payments (purchases of alcohol, so I guess buying coffee is not in scope for payment channels). Closing is done by creating a "final" transaction that is the sum of the individual payments. Sure there's no routing and channels are unidirectional and channels have a maximum lifetime but give Satoshi a break, he was also busy inventing Bitcoin at the time. Now if you noticed I called this kind of payment channel "broken". This is because the mempool rules are not consensus rules, and cannot be validated (nothing about the mempool can be validated onchain: I sigh every time somebody proposes "let's make block size dependent on mempool size", mempool state cannot be validated by onchain data). Fullnodes can't see all of the transactions you signed, and then validate that the final one with the maximum nSequence is the one that actually is used onchain. So you can do the below:
Become friends with Jihan Wu, because he owns >51% of the mining hashrate (he totally reorged Bitcoin to reverse the Binance hack right?).
Slip Jihan Wu some of the more interesting drinks you're ordering as an incentive to cooperate with you. So say you end up ordering 100 drinks, you split it with Jihan Wu and give him 50 of the drinks.
When the bar closes, Jihan Wu quickly calls his mining rig and tells them to mine the version of your transaction with nSequence 0. You know, that first one where you pay for only one drink.
Because fullnodes cannot validate nSequence, they'll accept even the nSequence=0 version and confirm it, immutably adding you paying for a single alcoholic drink to the blockchain.
The bartender, pissed at being cheated, takes out a shotgun from under the bar and shoots at you and Jihan Wu.
Jihan Wu uses his mystical chi powers (actually the combined exhaust from all of his mining rigs) to slow down the shotgun pellets, making them hit you as softly as petals drifting in the wind.
The bartender mutters some words, clothes ripping apart as he or she (hard to believe it could be a she but hey) turns into a bear, ready to maul you for cheating him or her of the payment for all the 100 drinks you ordered from him or her.
Steely-eyed, you stand in front of the bartender-turned-bear, daring him to touch you. You've watched Revenant, you know Leonardo di Caprio could survive a bear mauling, and if some posh actor can survive that, you know you can too. You make a pose. "Drunken troll logic attack!"
I think I got sidetracked here.
Bears are bad news.
You can't reasonably invoke "Satoshi's Vision" and simultaneously reject the Lightning Network because it's not onchain. Satoshi's Vision included a half-assed implementation of payment channels with nSequence, where the onchain transaction represented multiple logical payments, exactly what modern offchain techniques do (except modern offchain techniques actually work). nSequence (the field, but not its modern meaning) has been in Bitcoin since BitCoin For Windows Alpha 0.1.0. And its original intent was payment channels. You can't get nearer to Satoshi's Vision than being a field that Satoshi personally added to transactions on the very first public release of the BitCoin software, like srsly.
Miners can totally bypass mempool rules. In fact, the reason why nSequence has been repurposed to indicate "optional" replace-by-fee is because miners are already incentivized by the nSequence system to always follow replace-by-fee anyway. I mean, what do you think those drinks you passed to Jihan Wu are, other than the fee you pay him to mine a specific version of your transaction?
Satoshi made mistakes. The original design for nSequence is one of them. Today, we no longer use nSequence in this way. So diverging from Satoshi's original design is part and parcel of Bitcoin development, because over time, we learn new lessons that Satoshi never knew about. Satoshi was an important landmark in this technology. He will not be the last, or most important, that we will remember in the future: he will only be the first.
Incentive-compatible time-limited unidirectional channel; or, Satoshi's Vision, Fixed (if transaction malleability hadn't been a problem, that is). Now, we know the bartender will turn into a bear and maul you if you try to cheat the payment channel, and now that we've revealed you're good friends with Jihan Wu, the bartender will no longer accept a payment channel scheme that lets one you cooperate with a miner to cheat the bartender. Fortunately, Jeremy Spilman proposed a better way that would not let you cheat the bartender. First, you and the bartender perform this ritual:
You get some funds and create a transaction that pays to a 2-of-2 multisig between you and the bartender. You don't broadcast this yet: you just sign it and get its txid.
You create another transaction that spends the above transaction. This transaction (the "backoff") has an nLockTime equal to the closing time of the bar, plus one block. You sign it and give this backoff transaction (but not the above transaction) to the bartender.
The bartender signs the backoff and gives it back to you. It is now valid since it's spending a 2-of-2 of you and the bartender, and both of you have signed the backoff transaction.
Now you broadcast the first transaction onchain. You and the bartender wait for it to be deeply confirmed, then you can start ordering.
The above is probably vaguely familiar to LN users. It's the funding process of payment channels! The first transaction, the one that pays to a 2-of-2 multisig, is the funding transaction that backs the payment channel funds. So now you start ordering in this way:
For your first drink, you create a transaction spending the funding transaction output and sending the price of the drink to the bartender, with the rest returning to you.
You sign the transaction and pass it to the bartender, who serves your first drink.
For your succeeding drinks, you recreate the same transaction, adding the price of the new drink to the sum that goes to the bartender and reducing the money returned to you. You sign the transaction and give it to the bartender, who serves you your next drink.
At the end:
If the bar closing time is reached, the bartender signs the latest transaction, completing the needed 2-of-2 signatures and broadcasting this to the Bitcoin network. Since the backoff transaction is the closing time + 1, it can't get used at closing time.
If you decide you want to leave early because your liver is crying, you just tell the bartender to go ahead and close the channel (which the bartender can do at any time by just signing and broadcasting the latest transaction: the bartender won't do that because he or she is hoping you'll stay and drink more).
If you ended up just hanging around the bar and never ordering, then at closing time + 1 you broadcast the backoff transaction and get your funds back in full.
Now, even if you pass 50 drinks to Jihan Wu, you can't give him the first transaction (the one which pays for only one drink) and ask him to mine it: it's spending a 2-of-2 and the copy you have only contains your own signature. You need the bartender's signature to make it valid, but he or she sure as hell isn't going to cooperate in something that would lose him or her money, so a signature from the bartender validating old state where he or she gets paid less isn't going to happen. So, problem solved, right? Right? Okay, let's try it. So you get your funds, put them in a funding tx, get the backoff tx, confirm the funding tx... Once the funding transaction confirms deeply, the bartender laughs uproariously. He or she summons the bouncers, who surround you menacingly. "I'm refusing service to you," the bartender says. "Fine," you say. "I was leaving anyway;" You smirk. "I'll get back my money with the backoff transaction, and posting about your poor service on reddit so you get negative karma, so there!" "Not so fast," the bartender says. His or her voice chills your bones. It looks like your exploitation of the Satoshi nSequence payment channel is still fresh in his or her mind. "Look at the txid of the funding transaction that got confirmed." "What about it?" you ask nonchalantly, as you flip open your desktop computer and open a reputable blockchain explorer. What you see shocks you. "What the --- the txid is different! You--- you changed my signature?? But how? I put the only copy of my private key in a sealed envelope in a cast-iron box inside a safe buried in the Gobi desert protected by a clan of nomads who have dedicated their lives and their childrens' lives to keeping my private key safe in perpetuity!" "Didn't you know?" the bartender asks. "The components of the signature are just very large numbers. The sign of one of the signature components can be changed, from positive to negative, or negative to positive, and the signature will remain valid. Anyone can do that, even if they don't know the private key. But because Bitcoin includes the signatures in the transaction when it's generating the txid, this little change also changes the txid." He or she chuckles. "They say they'll fix it by separating the signatures from the transaction body. They're saying that these kinds of signature malleability won't affect transaction ids anymore after they do this, but I bet I can get my good friend Jihan Wu to delay this 'SepSig' plan for a good while yet. Friendly guy, this Jihan Wu, it turns out all I had to do was slip him 51 drinks and he was willing to mine a tx with the signature signs flipped." His or her grin widens. "I'm afraid your backoff transaction won't work anymore, since it spends a txid that is not existent and will never be confirmed. So here's the deal. You pay me 99% of the funds in the funding transaction, in exchange for me signing the transaction that spends with the txid that you see onchain. Refuse, and you lose 100% of the funds and every other HODLer, including me, benefits from the reduction in coin supply. Accept, and you get to keep 1%. I lose nothing if you refuse, so I won't care if you do, but consider the difference of getting zilch vs. getting 1% of your funds." His or her eyes glow. "GENUFLECT RIGHT NOW." Lesson learned?
Payback's a bitch.
Transaction malleability is a bitchier bitch. It's why we needed to fix the bug in SegWit. Sure, MtGox claimed they were attacked this way because someone kept messing with their transaction signatures and thus they lost track of where their funds went, but really, the bigger impetus for fixing transaction malleability was to support payment channels.
Yes, including the signatures in the hash that ultimately defines the txid was a mistake. Satoshi made a lot of those. So we're just reiterating the lesson "Satoshi was not an infinite being of infinite wisdom" here. Satoshi just gets a pass because of how awesome Bitcoin is.
CLTV-protected Spilman Channels
Using CLTV for the backoff branch. This variation is simply Spilman channels, but with the backoff transaction replaced with a backoff branch in the SCRIPT you pay to. It only became possible after OP_CHECKLOCKTIMEVERIFY (CLTV) was enabled in 2015. Now as we saw in the Spilman Channels discussion, transaction malleability means that any pre-signed offchain transaction can easily be invalidated by flipping the sign of the signature of the funding transaction while the funding transaction is not yet confirmed. This can be avoided by simply putting any special requirements into an explicit branch of the Bitcoin SCRIPT. Now, the backoff branch is supposed to create a maximum lifetime for the payment channel, and prior to the introduction of OP_CHECKLOCKTIMEVERIFY this could only be done by having a pre-signed nLockTime transaction. With CLTV, however, we can now make the branches explicit in the SCRIPT that the funding transaction pays to. Instead of paying to a 2-of-2 in order to set up the funding transaction, you pay to a SCRIPT which is basically "2-of-2, OR this singlesig after a specified lock time". With this, there is no backoff transaction that is pre-signed and which refers to a specific txid. Instead, you can create the backoff transaction later, using whatever txid the funding transaction ends up being confirmed under. Since the funding transaction is immutable once confirmed, it is no longer possible to change the txid afterwards.
Todd Micropayment Networks
The old hub-spoke model (that isn't how LN today actually works). One of the more direct predecessors of the Lightning Network was the hub-spoke model discussed by Peter Todd. In this model, instead of payers directly having channels to payees, payers and payees connect to a central hub server. This allows any payer to pay any payee, using the same channel for every payee on the hub. Similarly, this allows any payee to receive from any payer, using the same channel. Remember from the above Spilman example? When you open a channel to the bartender, you have to wait around for the funding tx to confirm. This will take an hour at best. Now consider that you have to make channels for everyone you want to pay to. That's not very scalable. So the Todd hub-spoke model has a central "clearing house" that transport money from payers to payees. The "Moonbeam" project takes this model. Of course, this reveals to the hub who the payer and payee are, and thus the hub can potentially censor transactions. Generally, though, it was considered that a hub would more efficiently censor by just not maintaining a channel with the payer or payee that it wants to censor (since the money it owned in the channel would just be locked uselessly if the hub won't process payments to/from the censored user). In any case, the ability of the central hub to monitor payments means that it can surveill the payer and payee, and then sell this private transactional data to third parties. This loss of privacy would be intolerable today. Peter Todd also proposed that there might be multiple hubs that could transport funds to each other on behalf of their users, providing somewhat better privacy. Another point of note is that at the time such networks were proposed, only unidirectional (Spilman) channels were available. Thus, while one could be a payer, or payee, you would have to use separate channels for your income versus for your spending. Worse, if you wanted to transfer money from your income channel to your spending channel, you had to close both and reshuffle the money between them, both onchain activities.
Poon-Dryja Lightning Network
Bidirectional two-participant channels. The Poon-Dryja channel mechanism has two important properties:
No time limit.
Both the original Satoshi and the two Spilman variants are unidirectional: there is a payer and a payee, and if the payee wants to do a refund, or wants to pay for a different service or product the payer is providing, then they can't use the same unidirectional channel. The Poon-Dryjam mechanism allows channels, however, to be bidirectional instead: you are not a payer or a payee on the channel, you can receive or send at any time as long as both you and the channel counterparty are online. Further, unlike either of the Spilman variants, there is no time limit for the lifetime of a channel. Instead, you can keep the channel open for as long as you want. Both properties, together, form a very powerful scaling property that I believe most people have not appreciated. With unidirectional channels, as mentioned before, if you both earn and spend over the same network of payment channels, you would have separate channels for earning and spending. You would then need to perform onchain operations to "reverse" the directions of your channels periodically. Secondly, since Spilman channels have a fixed lifetime, even if you never used either channel, you would have to periodically "refresh" it by closing it and reopening. With bidirectional, indefinite-lifetime channels, you may instead open some channels when you first begin managing your own money, then close them only after your lawyers have executed your last will and testament on how the money in your channels get divided up to your heirs: that's just two onchain transactions in your entire lifetime. That is the potentially very powerful scaling property that bidirectional, indefinite-lifetime channels allow. I won't discuss the transaction structure needed for Poon-Dryja bidirectional channels --- it's complicated and you can easily get explanations with cute graphics elsewhere. There is a weakness of Poon-Dryja that people tend to gloss over (because it was fixed very well by RustyReddit):
You have to store all the revocation keys of a channel. This implies you are storing 1 revocation key for every channel update, so if you perform millions of updates over your entire lifetime, you'd be storing several megabytes of keys, for only a single channel. RustyReddit fixed this by requiring that the revocation keys be generated from a "Seed" revocation key, and every key is just the application of SHA256 on that key, repeatedly. For example, suppose I tell you that my first revocation key is SHA256(SHA256(seed)). You can store that in O(1) space. Then for the next revocation, I tell you SHA256(seed). From SHA256(key), you yourself can compute SHA256(SHA256(seed)) (i.e. the previous revocation key). So you can remember just the most recent revocation key, and from there you'd be able to compute every previous revocation key. When you start a channel, you perform SHA256 on your seed for several million times, then use the result as the first revocation key, removing one layer of SHA256 for every revocation key you need to generate. RustyReddit not only came up with this, but also suggested an efficient O(log n) storage structure, the shachain, so that you can quickly look up any revocation key in the past in case of a breach. People no longer really talk about this O(n) revocation storage problem anymore because it was solved very very well by this mechanism.
Another thing I want to emphasize is that while the Lightning Network paper and many of the earlier presentations developed from the old Peter Todd hub-and-spoke model, the modern Lightning Network takes the logical conclusion of removing a strict separation between "hubs" and "spokes". Any node on the Lightning Network can very well work as a hub for any other node. Thus, while you might operate as "mostly a payer", "mostly a forwarding node", "mostly a payee", you still end up being at least partially a forwarding node ("hub") on the network, at least part of the time. This greatly reduces the problems of privacy inherent in having only a few hub nodes: forwarding nodes cannot get significantly useful data from the payments passing through them, because the distance between the payer and the payee can be so large that it would be likely that the ultimate payer and the ultimate payee could be anyone on the Lightning Network. Lessons learned?
We can decentralize if we try hard enough!
"Hubs bad" can be made "hubs good" if everybody is a hub.
Smart people can solve problems. It's kinda why they're smart.
After LN, there's also the Decker-Wattenhofer Duplex Micropayment Channels (DMC). This post is long enough as-is, LOL. But for now, it uses a novel "decrementing nSequence channel", using the new relative-timelock semantics of nSequence (not the broken one originally by Satoshi). It actually uses multiple such "decrementing nSequence" constructs, terminating in a pair of Spilman channels, one in both directions (thus "duplex"). Maybe I'll discuss it some other time. The realization that channel constructions could actually hold more channel constructions inside them (the way the Decker-Wattenhofer puts a pair of Spilman channels inside a series of "decrementing nSequence channels") lead to the further thought behind Burchert-Decker-Wattenhofer channel factories. Basically, you could host multiple two-participant channel constructs inside a larger multiparticipant "channel" construct (i.e. host multiple channels inside a factory). Further, we have the Decker-Russell-Osuntokun or "eltoo" construction. I'd argue that this is "nSequence done right". I'll write more about this later, because this post is long enough. Lessons learned?
Bitcoin offchain scaling is more powerful than you ever thought.
Wondering what's going on? Here's a list of quick facts about Basic Attention Token (BAT).
BAT is an Ethereum ERC20 token, which means you can use common hardware wallets like the Ledger Nano, MyEtherWallet, etc.
BAT is backed by Silicon Valley VCs like Peter Thiel’s Founders Fund, among others.
Coinbase CEO Brian Armstrong tweeted on March 30th, 2017 that BAT is “exactly the sort of token we'd like to support on Coinbase and GDAX over the coming year, make it easy to buy/sell these with gov currencies.”
One of BAT's close advisers is Ankur Nandwani, who is/was Product Manager at Coinbase. He was the one who announced that Litecoin was added to Coinbase.
$BAT was recently added to a spate of exchanges, including big Chinese exchanges like Binance and Huobi.
You will be able to get paid for choosing to view ads with the BAT Ads program. Users receive 70% of ad revenue. Yes, 70%.
Brave & BAT have been covered in a lot of mainstream news recently, including Bloomberg, NASDAQ, CNET, Engadget, TechCrunch and more. It has also been promoted by Ubuntu Linux (on their FB page with 1.3m followers) and Rocket.Chat (on their official blog).
BAT is not limited to the Brave web browser but will be extended to other browsers via extensions (where APIs permit) and other attention-economy apps like chat messengers, podcast apps, games, etc.
Brave Payments, which utilizes $BAT, currently supports YouTubers. Support for Twitch, Reddit and Twitter, etc. have been confirmed. Brave Payments allows you to easily tip your favorite publishers and content creators, Patreon-style.
Over 1000 websites and over 600 YouTubers have been confirmed as verified publishers with the Brave Payments program—and counting. This includes big channels like Phil deFranco who has 6 million subscribers. (You can still tip/donate to your favorite sites/creators even if they aren’t yet verified since the $BAT will be held in a wallet for them to claim.)
The Brave web browser has over 1 million active monthly users. On the Android store alone, Brave has 1-5 million downloads. Brave is available on all platforms (iOS, Android, Windows, MacOS, Linux).
Other notable figures on the development team include Yan Zhu (Forbes top 30 under 30, Tor Project, W3C, EFF), Marshall Rose (inventor of SNMP, Internet Engineering Task Force) as well as many others who’ve worked on major projects. (Look at team on website.)
The Brave browser has one-click support for Ethereum dApps with Metamask. Brave is officially listed on Metamask’s website alongside Google Chrome.
You will be able to purchase $BAT with your credit or debit card directly through the built-in BAT wallet in Brave. This is a first priority for the team.
And more... Edit (additions):
BAT officially partnered with privacy search engine DuckDuckGo, and they recently revealed more details on their relationship.
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