Tout sur BITCOIN David St-ONGE

 

• Pour faire simple, pour recevoir des bitcoins, vous avez besoin d'une clé publique et pour en dépenser, vous avez besoin d'un clé privée.
• La solution trouvée pour sécuriser la clé publique, c'est de la multiplier.
• L'une des fonctions du portefeuille Bitcoin: il vous permet de générer des adresses Bitcoins, qui sont en quelque sorte des clés publiques jetables.
• Le portefeuille conserve votre clé privée et utilise votre clé publique pour générer des adresses Bitcoin.
• UTXOs: "Unspent Transaction Output" que l'on pourrait traduire comme le solde d'une transaction qui n'a pas encore été utilisée.
• Il est quand même beaucoup plus sûr d'utiliser un Trezor ou un Ledger que de laisser vos jetons sur une plateforme d'échange ou un téléphone.
• Bitcoin n'est absolument pas un système confidentiel.
• Son utilisation laisse des traces numériques qui sont récupérées par des compagnies spécialisées qui revendent ou partagent ces informations avec les gouvernements et différentes autres entités.
• Vous n'avez pas besoin d'avoir quelque chose de grave à cacher pour souhaiter plus d'anonymat.
• BTCPay Server : une personne qui voudrait vendre des produits par Internet pourrait trouver laborieux de générer manuellement de nouvelles adresses dans son portefeuille à chaque transaction. C'est de ça que se charge BTCPay server.
• Mon ordinateur utilise facilement 400 Watts de puissance lorsqu'il est en train de miner.
• https://mynodebtc.com : il est possible d'installer leur produit sur un mini-ordinateur de type Raspberry Pi.
• Les changements dans la société ne viennent pas d'en haut, ils viennent des individus.

Bubble or Revolution - The Present and Future of Blockchain and Cryptocurrencies

 

Chapter 1: Bitcoin and the Blockchain

• Shared log, or ledger.
• Transactions are batched into blocks.
• The only way to mine a block is to guess nonces over and over until you win, like playing a digital lottery.
• The word nonce comes from "number used only once".

Chapter 2: Bitcoin Economics

• Intersubjective reality: you think this thing has value because you know that other people think it has value. Yuval Noah Harari.
• By one estimate, 30% of all mined bitcoins have been lost.
• The majority of Bitcoin users are speculators hoping to make a buck.
• The thing that makes currencies good is stability, while the thing that makes investments good is growth. These are, of course, mutually exclusive.
• Bitcoin may not be the future of money, but it may well be the future of investing.

Chapter 3: Bitcoin's Blunders

• Mempool: all unconfirmed transactions.
• Since Bitcoin can only process a few thousand transactions an hour (12000 to 15000 an hour at the time of writing), it took an average of 16 hours for a transaction to get confirmed and put on the blockchain.
• Fee spikes have become a common feature in Bitcoin rallies.
• Mike Hearn, a well-known early Bitcoin developer, estimated that Bitcoin could only handle about 3 transactions per second.
• The name "SegWit" is an abbreviation of "segregated witness"; the metadata with the signature is called the "witness", and it's "segregated" away from the main transaction data.
• The remarkable transparency of Bitcoin's blockchain makes Bitcoin far less anonymous than its supporters might make it out to be.
• The Bitcoin wallet is only as secure as its private key, and if someone gets ahold of that private key, the money is theirs, and if they steal it, it's practically irreversible.
• The only way to undo that theft is to make a "fork" of the blockchain that erases that theft from history.
• Experts say that the best approach is to keep long-term savings in cold storage and keep money for daily expenses in a normal internet-connected computer, known as "hot-storage".
• Bitcoin mining is a competition to waste the most electricity possible, by doing pointless arithmetic quintillion's of times a second.
• The University of Cambridge estimates that Bitcoin's annual energy consumption skyrocketed from about 6 Terawatt-hours (roughly the annual consumption of Luxembourg) in 2017 to over 80 terawatt-hours (roughly the annual power consumption of Finland in 2020)
• We're estimating that a MacBook can do one billion hashes per second, or 1GH/s.
• The popular pickaxe (pioche) theory argues that it's hard to get rich by participating in the latest technological craze, but it's very profitable to sell equipment to those who are.
• Bitmain now controls 70-80%. of the Bitcoin mining hardware market.
• Some smaller cryptocurrencies that are ASIC-Resistant, meaning that GPUs are actually the best way to mine them.
• At the time of writing, the number of Bitcoin full nodes hasn't budged from about 10000 in the last two years.
• This should worry any proponent of decentralization: the software that's at the heart of Bitcoin is primarily owned and maintained by a small group of people that are employed and funded by a single company. The potential for conflicts of interest and user-hostile changes by Blockstream is high

Chapter 4: Altcoins

• Bitcoin and Bitcoin Cash's blockchains, software, community, developers, and roadmap are all different now.
• Buterin's big idea was that blockchain can do more than just record transactions: they can run code, host apps, store data, and really do any kind of computation.
• The remarkable part of smart contracts like these is that they will always operate as intended, once they are set in motion, humans can't mess with their behavior.
• Non-blockchain-powered institutions that smart contracts have to trust are known as oracles.
• Without people to watch them, algorithms can do some unfair things.
• Just like with money, middlemen bring costs and benefits. It's not always a good thing to get rid of them, but with DApps, at least there's an alternative to middlemen for situations where getting rid of them makes sense.
• Art critics are hailing the blockchain as the potential future of arts and culture: there's finally a way to prove that you, and only you, own a piece of digital art.
• While Bitcoin aims to be an investment vehicle and Ethereum aims to be an app platform, another class of cryptocurrencies, stablecoins, aims to be just a classic payment system.
• The best-known stable coin is called Tether: each Tether coin (known as a USDT, for US dollar Tehtehr) always trades at $1.
• CDP: Collaterized Debt Position.
• You borrow DAI coins by using your ether as collateral; this loan is a CDP.
• MakerDAO runs another currency named MKR.
• ICO:Initial Coin Offerings, a crypto version of initial Public Offerings, or IPOs, when startups start selling shares on the stock market.
• Bitcoin isn't really anonymous. Every single payment is stored public and permanently on the blockchain, ssh anyone can see how wealthy people are, who does business with whom, and where money has flowed.
• Monero is popularly known as privacy coin.
• You can have a web browser run a snippet of Javascript code, the same kind of code that makes websites like Spotify and Google Docs Interactive, to mine Monero coins.
• You can see why crypto jackers love Monero: it's easy to mine it on a browser, and since it's totally anonymous, the crooks don't leave any fingerprints behind. This illustrates one of the fundamental tensions of cryptocurrencies: anything designed to promote privacy and anonymity, which are usually good things, ends up helping criminals more than anyone else.

Chapter 5: Public Blockchains

• The idea of blockchain voting relies on tokens, which are digital assets whose movement can be tracked on the blockchain.
• The big difference between tokens and ether is that anyone can create a token out of nothing and issue as many tokens as they want, whereas ether is the only official form of money on Ethereum, and new ether can only be madly mining.
• One potential solution to the anonymity problem is called homomorphic encryption.
• If you put a link to a webpage in a book or document or other webpage, there's a 50% chance that the link will no longer work after seven years.
• A project called FileCoin aims to pay people who store copies of IPFS files on their computers.
• No matter what blockchain you use, blockchains are slow: a classic centralized database called MySQL can handle 60000 times more transactions per second than Ethereum (which itself can handle five times as many as Bitcoin)
• The top selling points of blockchains are that they're decentralized, trustless, transparent, and tamper-proof.
• Blockchains are great technological innovations, but they aren't enough to drive social change, you have to think hard about getting people and institutions to change their behavior.
• That's a common problem for blockchain apps: focusing too much on the technical problems without thinking about the people problems.

Chapter 6: Business on the Blockchain

• Benefits: decentralization (many computers still keep copies of the blockchain), immutability (proof-of-work still makes it hard for an attacker to forge blocks) and transparency (everyone can get exactly the information they need without having to hunt down people across companies.
• Azure's blockchain-as-a-service feature.
• Blockchain technology has a remarkable amount of overlap with some of the other hot technology trends: cloud computing, big data, and machine learning.
• Implementing a private blockchain ins't really a technical challenge at all; it's a social challenge.
• In all three cases we explored, the hard part has been the people part.
• For most private e blockchains projects, it's not the technology that matters, it's getting adoption, getting people comfortable with change, and working out all the legal and financial difficulties that come up.

Chapter 7: Cryptocurrency Policy

• Exit scam: it's when a company raises money based on a white paper but disappears before building anything.

Chapter 8: What's next

• It had been rumored for years that Facebook would be adding a stable coin to WhatsApp and Messenger.
• But why would a social networking company get into crypto? The most obvious reason was that it would help Facebook track exactly what people where spending money on; which would be extremely valuable data for advisers.
• We think cryptocurrencies will primarily be used behind the scenes, such as for transactions between banks or for large payments between companies.
• China has made no secret that it's trying to make its yuan the world's primary reserve currency.
• Then we think China will build a prototype tokenized yuan and test it in Africa. China is Africa's largest economic partner and has been investing heavily in infrastructure throughout the continent. Given how volatile African currencies are, large swaths of the continent may welcome the relative transparency and stability of a tokenized yuan. Perhaps China will create a yuan-backed "Afro" currency that is adopted  throughout Africa, similar to the Euro in Europe.
• For IoT to succeed, IoT devices need a secure, tamper-proof, and decentralized way to store, access, and share data.

Chapter 9: Bubble or Revolution?

• Bitcoin futures, which are contracts saying a buyer will buy a certain number of items for a certain price at a certain time.
• The regulation is, on the whole, a good thing for crypto.
• So, while inflation is usually a bad thing for investors, it's a good thing for gold holders.
• It's clear that the two biggest use cases for cryptocurrencies going forward will be as payment methods (primarily for large or international transfers) and as investments (supplementing, but not replacing, stocks and bonds).
• Countries are adopting cryptocurrency, but by tokenizing their existing fiat currencies.
• The idea of an immutable, shared history of past transactions is extremely powerful.
• The technologists who created blockchain and cryptocurrencies were better at solving the thorny technical problems and not these social problems.

Wanting - Luke Burgis

 

• Sur le plan individuel, selon Girard, les hommes se haïssent parce qu'ils s'imitent. Le mimétisme engendre la rivalité, mais en retour la rivalité renforce le mimétisme. Il y a double logique, celle du désir et celle de l'imitation. En d'autres termes, faire de l'autre un modèle, c'est faire de lui un rival.
• www.lukeburgis.com

Introduction

• How my desires entrapped me in cycles of passion followed by disillusionment.
• Mimetic theory isn't like learning some impersonal law of physics, which you can study from a distance. It means learning something new about your own past that explains how your identity has been shaped and why certain people and things have exerted more influence over you and others.
• The truth is that desires are derivative, mediated by others, and that I'm part of an ecology of desire that is bigger than I can fully understand.Girard discovered that we come to desire many things not through biological drives or pure reason, nor as a decree of our illusory and sovereign self, but through imitation.
• It is models, not our "objective" analysis or central nervous system, that shapes our desires.
• Like a lot of high school students, he strived to gain admission to a prestigious university without questioning why he wanted to go there in the first place.
• "Human being fights not because they are different, but because they are the same, and in their attempts to distinguish themselves into enemy twins, human doubles in reciprocal violence" Girard.
• In Girard's view, the root of the most violence is mimetic desire.
• "You find yourself trapped in all these bad mimetic cycles". Girard.
• When there was risk of an all-out war with Elon Musk's rival company, X.com, Thiel merged with him to form PayPal.
• Reid Hoffman, the founder of LinkedIn.
• Facebook was build around identity, that is to say, desires. It helps people see what other people have and want. It is platform for finding, following, and differentiating oneself from models.
• Models of desire are what make Facebook such a potent drug.
• I bet on mimesis.
• History is the story of human desire.
• The terrorists would not have been driven to destroy symbols of the West's wealth and culture if, at some deep level, they had not secretly desired some of the same things.
• "The Power of Mimetic Desire" is about the hidden forces that influence why people want the things they want.
• We're becoming more aware of how fragile and interconnected the world's systems are. 
• Public health has been challenged because even the best policies have to contend with groups of people who want different things.

The Power of Mimetic Desire

Hidden models

• The Romantic Lie is self-delusion, the story people tell about why they make certain choices: because it fits their personal preferences, or because they see its objective qualities, or because they simply saw it and therefore wanted it. They believe that there is a straight line between them and the things they want. That's a lie.
• People paying attention to other people's eye and reading things about their intentions and desires.
• Start with "why"
• Desire is the better place to start.
• If we receive a response to an email or text that doesn't sufficiently tone-match, we can go into a mini-crisis (Does she not like me? Does he think he's superior to me?  Did I do something wrong?). Communication practically runs on mimesis.
• My friend has become a model of desire to me.
• I'll start to make decisions based on what he wants.
• In the passage from childhood to adulthood, the open imitation of the infant becomes the hidden mimesis of adults.
• Mimetic desire operates in the dark. Those who can see in the dark take full advantage.
• He had seen opportunities where others saw obstacles.
• Models influence desire.
• Name your models. Think seriously about the people you least want to succeed.
• She influenced my desire by denying it.
• It's the Paradox of Importance: sometimes the most important things in our lives come easily, they seem like gifts, while many of the least important things are the ones that, in the end, we worked the hardest for.
• Efficient market theory is the belief that asset prices are functions of all available information.
• "Conformity is a powerful force that can counteract gravity for longer than skeptics expect". Jason Zweig.

Distorted Reality

• Imitate me, but not too much.
• Because rivalry is a function of proximity.
• Satoshi Nakamoto boosted his mimetic value into the upper stratosphere of Celebristan through secrecy.
• We are most likely to take someone as a model if they don't seem to be suffering from desire like us.
• Cats are mercurial (changeant). They usually seem uninterested in your opinion.
• Liquid modernity is a chaotic phase of history in which there are no culturally agree-upon models to follow, no fixed points of reference.
• The modern world is one of experts.
• We're model addicts. Right now, the models we prefer are experts.
• Principle of reflexivity. In situations that have thinking participants, there is a two-way interaction between the participants thinking and the situation in which they operate. Investors perceive there might be a crash, so they behave in a way that participates to the crash.
• People worry about what other people will think before they say something, which affects what they say.
• "Spiral of silence". Elisabeth Noelle-Neumann.
• People who believe their opinions are not shared by anyone else are more likely to remain quiet; their silence itself increases the impression that no one else thinks as they do. This increases their feelings of isolation and artificially inflates the confidence of those with the majority opinion.
• Winston Churchill: "We shape our buildings; thereafter they shape us"
• Mimetic desire is a truth at the heart of human relations;
• Our addiction to the desires of others, which smartphones give us.
• Mimetic desire is the real engine of social media.

Social Contagion

• "If individuals are naturally inclined to desire what their neighbors possess, or to desire what their neighbors even simply desire, this means that rivalry exists at the very heart of human social relations. This rivalry, if not thwarted, would permanently endanger harmony and even the survival of all human communities" René Girard.
• Karl Max and William Shakespeare had very different views about why people fight. Marx thought conflict happens because people are different. Shakespeare's view seems to be exactly the opposite: people fight when they are similar.
• Soccer stars Christiana Ronaldo and Lionel Messi may be celebrities to most of us, but to each other they are not. The same was now true of Ferrari and Lamborghini.
• In a bullfight, a bull is maneuvered into submission not by strength but by agility and psychology.
• Lanborghini enjoyed a peaceful final twenty years of his life in his vineyard, giving guests personal tour off his estate.
• "Meme". Richard Dawkins was attempting to explain the spread across time and space of nonmaterial things such as ideas, behaviors, and phrases. He called these things memes: cultural units of information that spread from person to person through a process of imitation.
• An internet meme is a deliberate alteration of something.
• To try to forge an identity relative to other people.
• They were too many changes, too fast, including the adoption of an experimental flat management structure. It created chaos.
• Most people gauge their happiness relative to other people.
• A good leader needs to consider the impact of their decisions on human ecology, the web of relationships that affect human life and development. No aspect of human ecology is more overlooked than mimetic desire.
• The idea and organization needed to come from someone other than me for not to feel like a top-down imposition of cultural expectations.
• Like the value of protecting the health and safety of all employees versus keeping the business running during the COVID-19 pandemic.
• Remember that conflict is caused by sameness, not by difference.

The Invention of Blame

• The scapegoat mechanism turns a war of all against all into a war of all against one. It brings temporary peace as people forget their mimetic conflicts for a while, having just discharged all their anger onto a scapegoat.
• The scapegoating mechanism does no hinge on the guilt or innocence on the scapegoat. It hinges on the ability of a community to use a scapegoat to accomplish their desired outcome: unification, healing, purgation, expiation. The scapegoat serves a religious function.
• Anger spreads faster than other emotions, such as joy, because anger spreads easily when they are weak ties between people, as they are often online.
• A mimetic model, a person who knows what he wants.
• Nearly all people are religious in the sense that they subconsciously believe that sacrifice brings space.
• If only we could destroy that other political party, that other company, those terrorists, that troublemaker, that fast-food joint next door that has caused me to gain ten pounds, everything would be better. The sacrifice always seems right and proper. Our violence is good violence; the violence of the other side is always bad.
• The original scapegoat mechanism brought order out of chaos, but the order depended on violence. The reverse process brings chaos out of order. The chaos is meant to shake up the "orderly" system, predicated on violence, until something serious is done to change. The death of George Floyd in the United States in May 2020 is one salient example.
• One claims victim status as a way of gaining advantage or justifying one's behavior.
• Protect me from what I want.

The Transformation of Desire

Anti-mimetic - Feeding the People, Not the System

• What have we done in the past, where are we today, and what do we want for tomorrow?
• Nobody will question your goals.
• But it's worth asking where goals come from in the first place. Every goal is embedded within a system.
• Mimetic desire is the unwritten, unacknowledged system behind visible goals.
• And that's when I began my miserable fifteen-month career in Advanced Excel and PowerPoint.
• Social media platforms thrive on mimesis. Twitter encourages and measures by showing how many times each post has been retweeted.
• The deathbed is where unfulfilling desires are exposed. Transport yourself there now rather than waiting until later, when it might be too late.

Disruptive Empathy

• If I decline to shake your hand, if, in short, I refuse to imitate you, then your are now the one who imitates me, by reproducing my refusal, by copying me instead. Imitation, which usually expresses agreement in this case, now serves to confirm and strengthen disagreement. Once again, in other words, imitation triumphs. 
• A negative mimetic cycle is disrupted when two people, through empathy, stop seing each other as rivals.
• The em - in empathy means "to go into". It's the ability to go into the experiences or feelings of another person, but without losing self-possession, or the ability to maintain control over our responses and to act freely, out of our own core.
• Empathy means finding a shared point of humanity through which to connect without sacrificing our integrity in the process.
• A person who is able to empathize can enter the experience of another person and share her thoughts and feelings without necessarily sharing her desires.
• Thick desires are protected from the volatility of changing circumstances in our lives.
• The desire to retire is a thin desire, filled with mimetically derived ideas about the things one might do, or not do, in this ideal state. The desire to invest more time with family, on the other hand, is thick desire.
• Peuple seeking professional prestige, respect or admiration for their talents, without realizing that the pursuit of prestige is the pursuit of Fata Morgana.
• Tell me about a time in your life when you did something well and it brought you a sense of fulfillment.
• The interior dimension of an action: What was the person's motivation for taking it? What were the circumstances? How did the action affect them on an emotional level?
• MASTER: a person motivated to MASTER wants to gain complete command of a skill, subject, procedure, technique or process.
• COMPREHEND AND EXPRESS: a person with this core drive wants to understand, define, and then communicate their insights in some way.
• If she reads a book, she is compelled to review it on her blog.
• Serving other people, contributing to the success of the team, fighting injustice, organizing an effort that serves the common good.

Transcendent Leadership

• Desires don't magically and spontaneously happen. They are generated and shaped in the dynamic world of human interaction. Someone has to supply a model.
• Transcendent leaders have models of desire outside the systems they are in. The greatest writers and artists in history were driven by them, and that's why their work are timeless. They were not confined to the popular desires of their age.
• Shift gravity.
• They wanted to grow up, carve out their place in the world, grow in dignity.
• The speed of truth.
• In times of crisis, the threat from inside a company is underestimated. People who don't want to take  responsibility find scapegoats.
• The health of any human project that relies on the ability to adapt depends on the speed at which truth travels.
• Discernment
• We're not always as rational as we think. Nobel Prize winners Daniel Kahneman, Amos Tversky, and Richard Thaler have demonstrated how easily we can be deceived.
• Sit quietly in a room.
• "All of humanity's problems stem from man's inability to sit quietly in a room alone" Blaise Pascal.
• Invest in deep silence
• Filter feedback
• The MVP is "that version of a new product which allows a team to collect the maximum amount of validated learning about customers with the least effort".
• It's politics by polling, in which a candidate does whatever the polls tell them to do.

The mimetic future

• The model that we adopt for the future is critical to the formation of our desires.
• What we will want in the future depends on three things: how desire was formed in the past, how it is formed in the present, and how it will be formed in the future.
• Facebook is an endless stream of models in the form of other people's curated lives.
• The internet, despite creating enormous economic value by connecting the world, accelerated mimetic rivalry and diverted attention from innovation in others areas.
• But I can't help but think that the proliferation of these shows, thousands of them, with cooking competitions looping non-stop on twenty-four-hour food channels is symptomatic of our cultural stagnation and decadence.
• Google is like a deity that answers our questions. Facebook satisfies our need for love and belonging. Amazon fulfills the need for security, allowing us instantaneous access to goods in abundance. Apple appeals to our sex drive and the associated need for status, signaling one's attractiveness as a mate by associating with a brand that is innovative, forward-thinking, and costly to own.
• We lack a transcendent reference point outside the system.
• Hope is the desire for something that is (1) in the future, (2) good, (3) difficult to achieve, and (4) possible.
• "Life after Google: The Fall of Big Data and the Rise of the Blockchain Economy" George Gilder. 
• Ideologies are closed systems of desire.
• Wise people have said that it is best to compare to yourself only to who you were yesterday, not to who other people are today.
• People's desires are artificially shaped by external forces.
• Sometimes the market isn't a good indication of what people want. It's good at price discovery for thin desires, but not necessarily for thick ones.
• We must make a decision about what it is that is worth sinking our teeth into.
• The transformation of desire happens when we become less concerned about the fulfillment of our own desires and more concerned about the fulfillment of others.

Afterword

• Life is a process of ever-evolving desire.
• "Extremistan", "Mediocristan", "Celebristan", "Freshmanistan"
• "Man is the creature who does not know what to desire, and he turns to others in order to make up his mind". René Girard.

Motivational Themes

• Top three core motivational themes
• I trained and competed in a marathon.
• EXCEL: Maybe you compete against yourself in efforts that test your limits and stimulate you to stretch yourself to develop your skills. You want to establish a reputation that confirms the excellence of your work. In general, you want to do better than others, for example, to be the fastest or most effective.
• OVERCOME: You are motivated to struggle with the factors working against you until you overcome them.
• MASTER: Your motivation is satisfied when you are able to gain complete command of a skill, subject, procedure, technique, or process. It could be that you concentrate on the principles behind an engineering problem. Your thinking and talents are oriented toward mastery, your goals toward perfection.
• Susan Blackmore, an expert of meme theory and author of "The Meme Machine" is explicit about the role of imitation.

The Blocksize war - Jonathan Bier

 

• The dream of a world where ordinary people have ultimate and direct control over the rules that govern their money.

First Strike

• Mike Hearn and Gavin Andresen.
• Bitcoiners were typically anarcho-capitalists or libertarians who strongly supported free speech.
• People tend to like reading things they agree with and follow people they agree with. Confirmation bias features heavily on social media platforms and causes polarization.

March To War

• This type of upgrade was called a softfork, i.e. a new rule tightening restrictions on block validity. It is a softfork because adding or lowering the limit tightens the rules. Increasing the limit would relax the rules and is therefore known as a hardfork.

Scaling I - Montréal

• The company appeared to be perpetually worried about the risk of high inflation, driven by monetary easing from central bankers and the prospect of large fiscal deficits.
• There was no real distinction between validating nodes and mining nodes.

Scaling II- Hong Kong

• The same was said about the French insurer AXA, whose venture arm also invested in Blockstream. The former CEO of AXA was Henri de Castries, chairman of the steering group for the Bildeberg meeting, a close-door gathering of the world's financial and political elites, which provided perfect material for conspiracy theorists.
• Proof of work was there to solve the double spending problem.
• Roger Ver backing companies such as Blockchain.info, Bit pay and Kraken.

SegWit

• SegWit is a way of increasing the Bitcoin block size, without the new client being incompatible (I.e. it was soft fork rather than a hard fork ). A Bitcoin transaction consists of various components, one of which is the signature, authorizing the spend. This signature is typically the largest part of the transaction, based on the amount of data. SegWit was a new transaction format, where the signature would not need to be included in the old block, which still had a 1MB limit.
• Bitcoin is more than just engineering and computer science. It is also a social system, a live payment system, an economic system, and a financial system.

Lightning Network

• Lightning essentially works by aggregating multiple payments into a smaller number of Bitcoin transactions. Bitcoin transactions are used to open payment channels, which, once set up, facilitate a flow of multiple payments. Entities can have channels with many different counterparts, forming a network of channels. Payments can then find a path along the channels, which are already connected to each other, until they reach the final recipient.
• To some of the small blockers, this layer-two architecture made much more sense for a high capacity and cheap global payment system. On-chain, blockchain-based payment system typically work in a "broadcast to everyone" mode, in that when one make a payment, one needs to broadcast the transaction to all participants network. All participants are then required to process this transaction to see if it's a payment to them. This system is considered highly inefficient, especially for small payments. If someone is buys a coffee in France using Bitcoin, why should a merchant selling concert tickets in Japan needs to examine the transaction? That is essentially how on-chain Bitcoin payments worked and, to small blockers, the architecture made little sense for small payments; it was only needed as a base layer of a monetary system.
• Instead of broadcasting a transaction to everyone, the transaction can be send more directly to the payment recipient, more of a peer-to-peer architecture. If one of the parties to the transaction is dishonest and tries to steal money, then the other party can broadcast a transaction to the Bitcoin blockchain and reclaims the funds. The blockchain, and Bitcoin's proof-of-work consensus mechanism, is therefore used as a dispute resolution service. When both parties are honest, the nuances, inefficiencies and scalability constraints of the proof-of-work process can be avoided.
• Large blockers could claim, with some legitimacy, that the small blockers were highly intelligent computer geeks biased towards complex, technically elegant, but impractical solutions.
• At the time of writing, although the lightning network is gaining traction and the technology is rapidly improving, merchant adoption of the lightning network is limited.

The DAO

• In the summer of 2016, a project called the "DAO" (Decentralized Autonomous Organization) began to grab the attention of many inside the cryptocurrency community. The DAO was a smart contract built on Ethereum and styled itself as a kind of autonomous investment fund. Rather than the stodgy (lourd), old top-down-managed investment funds, the DAO would make investments as determined by votes from its users and would be governed by the code in the smart contract, rather than the law.
• The opportunity to make money was the primary driver of this trend. The success of Ethereum had driven a wave of copycats and new coin offerings.

Exchanges

• The most significant change was the emergence and growth of several cryptocurrency exchange businesses, whose success was driven by considerable demand from the retail market in the Asia Pacific region. Companies such as Poloinex, BitMEX and, perhaps most significantly of all, Bitfinex.

ASICBoost

• ASICBoost is a way to reduce the amount of work a miner is required to do when making a hashing attempt for Bitcoin's proof of work (PoW). SHA256, which is the hashing algorithm used for Bitcoin's PoW, splits the block header into 64-byte chunks before the computation occurs.
• As of today, more than 70% of Bitcoin blocks are mined using overt (déclaré) ASICBoost.

Dragons'Den

• The co-author of the lightning white paper, Joseph Poon.
• Bram Cohen, the inventor of Bittorrent.

Litecoin

• Unlike Bitcoin, which had a 95% activation threshold, Litecoin had a 75% miner activation threshold. Litecoin had the same two week rolling activation windows, followed by a two-week grace period.
• UASF: User Activated Soft Fork.
• This was clearly a good start to 2017 for the small blockers. They had achieved three victories in a row: exchanges, ASICBoost and now Litecoin.

User-Activated Softfork

• Segwit increases the block size, fixes transaction malleability, and makes scripting easier to upgrade as well as many other benefits.
• "Bitcoin is valuable in part because it has high security and stability; segwit was carefully designed to support and amplify that engineering integrity that people can count now and in the future." "First do no harm". Gregory Maxwell.

New-York agreement

• There are two group of people which have two different visions for Bitcoin. None of these visions is "wrong". One group values more things like decentralization, lack of government, censorship resistance, anonymity. This group thinks that Bitcoin will transform our world in 20-30 years. To reach this goal, it's of utter importance to stick to those values. There is no rush. The other group values more things like reaching one billion users in the next 5 years, or serving real unbanked users today, even if that requires a political agreement now.

Bitcoin cash

• The new alternative would exclude SegWit.

SegWit2x

• Most people just wanted to be on the winning side.
• The large blockers never really supported SegWit2x, their hearts went to Bitcoin Cash.

Victory

• Bitcoin remains the greatest form of money mankind has ever seen, and we remain dedicated to protecting and fostering its growth worldwide.
• It was now, finally, widely accepted that arranging meetings with large corporates in the space and trying to decide on changes to the protocol rules would not work.
• End users always control Bitcoin.
• Over this two-year battle, the small blockers and users had overcome the miners and the large businesses in the space, and, despite their large blocker adversaries investing literally hundred of millions of dollars into the cause, the small blockers won an incredible and resounding victory. Bitcoin demonstrated that it could be the user-controlled money, that it was always meant to be.

La vigne au 10 juillet 2021

Les raisins ont déjà une taille avancée

Maladie au dos de certaines feuilles : érinose ?

Beaucoup d'érigérons dans la vigne

 

Les vendanges il y a 70 ans

 

Les vendanges il y a quelques années (1951)

Tonton Jean et Monsieur Chagneux

Vin de Grece

 Vin biologique offert par Christos au nom déjà connu :=) Persistance en bouche et parfum de fût de chêne.

La vigne au 13 juin 2021

 

La vigne au 13 juin avant le relevage

Après le relevage et le cisaillage. Tonte de l'herbe entre les rangs.

La fleur est passée 

La vigne au 22 mai 2021

 

Avant le passage de la tondeuse

Après le passage de la tondeuse. Reste à faire entre les ceps.

J'ai prélevé vingt feuilles pour faire une analyse par fluorimétrie

Les résultats de l'analyse : il y a une carence en azote

La vigne au 14 mai 2021

 Quelques photos de la vigne au 14 mai :

.

On voit les raisins en formation

J’ai profité de l’éclaircie pour « monder » la parcelle

Vu de la colline de Brouilly depuis la parcelle

J’ai compté 9 raisins sur un cep

Polygon

• Polygon is a Commit Chain.
• Commit chains (extract from Mastering Blockchain):
• are a more generic term for Vitalik Buterin's plasma proposal. (http://plasma.io)
• are referred as non-custodial side chains but without a new consensus mechanism, as it is the case for side chains. They rely on main chain consensus mechanism, so they can considered as safe as the main chain. The operator of the commit chain is responsible for facilitating communication between transacting participants and sending regular updates to the main chain. See https://eprint.iacr.org/2018/642.pdf

Useful links

• https://ethhole.link/
• https://twitter.com/0xPolygon

Mastering Blockchain - Imran Bashir - Part II

 

 

Chapter 11: Ethereum 101

• Vitalik Buterin conceptualized Ethereum (https://ethereum.org)
• Decentralized Applications (DApps): this concept is in contrats to Bitcoin, where the scripting language is limited and only allows necessary operations.
• Ethereum 1.x: Proof-of-Work (PoW)
• Ethereum 2.x: Proof-of-Stake (PoS)
• Serenity release is ETH2.0.
• Ethereum, just like any blockchain, can be visualized as a transaction-based state machine.
• The transaction is digitally signed by the sender as proof that he is the owner of the ether.
• The transaction is then picked up by nodes called miners on the Ethereum network for verification and inclusion in the block.
• The details of the transaction can be visualized: https://etherscan.io/
• This hash is the unique ID of the transaction that can be used to trace this transaction throughout the blockchain network.
• The Ethereum network is a peer-to-peer network where nodes participates in order to maintain the blockchain and contribute to the consensus algorithm.
• Ethereum client is Geth: provides various functions such as mining and account management.
• Keys and addresses: The private key is a generated randomly and is kept secret; whereas public key is derived from the private key. Addresses are derived from public keys and are 20-byte codes to identify accounts. 
• Accounts are one of the main building blocks of the Ethereum blockchain. They are defined by pairs of private and public keys.
• Ethereum is a transaction-driven state machine.
• In case of transaction failure due to insufficient account balance or gas, all state changes are rolled back except for the feee payment, which is paid to the miners.
• The Contracts Accounts: the code is executed by the EVM (Ethereum Virtual Machine) by each mining node on the Ethereum network.
• Accounts allow interaction with the blockchain via transactions.
• A transaction in Ethereum is a digitally signed data packet using a private key that contains the instructions that either result in a message call or contract creation.
• Nonce: the nonce is a number that is incremented by one every time a transaction is sent by the sender. It must be equal to the number of transactions sent and is used as a unique identifier for the transactions.
• Gas price: the gas price represents the amount of Wei required to execute the transaction.
• A block is a data structure that contains batches of transactions. Transactions can be found in either transactions pools or blocks. In transaction pools, they wait for verification by a node, and in blocks, they are added after successful verification.
• Ehtereum's PoW is called Ethash and was originally designed to be ASIC resistant.
• Recursive Length Prefix (RLP) is linked to serialization and deserialization which are also referred as marshaling and un-marshaling respectively. Some commonly used serialization formats include XML, JSON, YAML, protocol buffers and XDR.
• Message calls result in a state transition. A message call is the act of passing a message from one account to another. If the destination account as an associated EVM code, then the EVM will start upon the receipt of the message to perform the required operations.
• Messages are similar to transactions; however, the main difference is that they are produced by the contracts.
• A call basically runs message call transactions locally on the client and never costs gas nor results in a state change.
• At a fundamental level, the Ethereum blockchain is a transaction and consensus-driven state machine.
• Code hash: this is an immutable field that contains the hash of the smart contract code that is associated with the account.
• After the Decentralized Autonomous Organization (DAO) hack, a hard fork was proposed: Ethereum classic and its currency represented by ETC, whereas the hard-forked version is ETH.
• The EVM is a simple stack-based execution machine that runs byte code instructions to transferm the system state from one state to another. Last In First Out (LIFO).
• EVM optimization is an active area of research.
• WebAssembly (Wasm) was developed by Google, Mozilla and Microsoft.
• Precompiled contracts can potentially become native extensions and might be included in the EVM opcodes in the future.
• Next hard fork release of Ethereum called Berlin will introduce new pre-compiled contracts for BLS12-381 curve operations with other updates.

Links

• https://ethereum.org
• https://etherscan.io/

Acronyms

• OOG: Out of Gas

Translation

• immutable: immuable
• 
  

Mastering Blockchain - Imran Bashir

 

• Préambule

• Un livre référence pour qui s'intéresse à la blockchain d'un point de vue fondamental.
• Un mois de lecture du 12 mars au 14 avril.
• Une approche approfondie qui va des bases du concept de livre des transactions partagées, aux protocoles de consensus, aux applications distribuées, aux cryptos monnaies, à l'ethereum, au web3 etc...
• Mes notes de lecture en résumé ci-dessous.

• Chapter 1: Blockchain 101

• Multiple confirmations of a transaction over time provide consistency in Bitcoin. For this purpose, the process of mining was introduced in Bitcoin. 
• Mining is a process that facilitates the achievement of consensus by using the PoW algorithm.
• With physical cash, it is almost impossible to trace back spending to the individual who actually paid the money.
• Smart contract: code needed to execute a required function when certain conditions are met.
• Smart property: it is possible to link a digital or physical asset to the blockchain in such a secure and precise manner that it cannot be claimed by anyone else.
• Enterprise Ethereum Alliance
• Hyperledger

• Chapter 2: Decentralization
• Many exiting applications and ideas emerge from the decentralized blockchain technology, such as decentralized finance and decentralized identity.
• A significant innovation in the decentralized paradigm is decentralized consensus.
• Blockchain can serve as a decentralized health record management system where health records can be exchanged securely  and directly between different entities.
• Not everything can or needs to be decentralized.
• There are systems that pre-date blockchain and Bitcoin, including BitTorrent and the Gnutella file-sharing system.
• IPFS and BigChainDB are more suitable for storing large amounts of data in a decentralized way.
• Many services hat a government commonly offers can be delivered via blockchains such as government identity card systems, passports, and records of deeds, marriages and births.
• Web 3 = decentralized internet

• Chapter 3: Symmetric cryptography

• Symmetric cryptography refers to a type of cryptography where the key that is used to encrypt the data is the same one that is used for decrypting the data.
• Hash functions play a vital role in blockchain.
• The SHA-256 algorithm is used in Bitcoin's PoW algorithm.
• Chapter 4: Public key cryptography
• Asymmetric cryptography refers to a type of cryptography where the key that is used to encrypt the data is different from the key that is used to decrypt the data. These keys are called private and public keys.
• Digital signatures are used to provide data origin authentication and non-repudiation.
• Hash functions are used to build Merkle trees.
• Hash functions are of particular importance in blockchains, as they are key to constructing Merkle trees, which are used in blockchains for the efficient and fast verification of large datasets.

• Chapter 5: Consensus algorithm
• In distributed systems, a common goal is to achieve consensus (agreement) among nodes on the network even in the presence of faults.
• State machine replication is a standard technique to achieve fault tolerance in distributed systems.
• In an asynchronous environment, the deterministic consensus is impossible.
• Liveness means that the protocol can make progress even if the network conditions are not ideal.
• PBFT (Practical Byzantine Fault Tolerant) provides immediate and deterministic transaction finality. This is in contrast with the PoW protocol, where a number of confirmations are required to finalize a transaction with high probability.
• IBFT (Istanbul Byzantine Fault Tolerant): validators can be added or removed by voting between members of the network.
• Nakamoto consensus, or PoW, is the longest-running blockchain network. 
• The PoW is designed to mitigate Sybil attacks. 
• A Sybil attack is a type of attack that aims to gain a majority influence on the network to control the network. Its a type of attack where a single adversary creates a large number of nodes with fakes identities on the network, which are used to gain influence on the network. This attack is also prevented in Bitcoin by using PoW, where miners are required to consume a considerable amount of computing power to earn rewards.
• The key idea behind PoW as a solution to the Byzantine generals problem is that all honest generals (miners in the Bitcoin world) achieve agreement on the same state (decision value). Note that this is a probabilistic solution and not deterministic.
• PoS (Proof of Stake) mechanisms generally select a stake holder and grant appropriate rights based on their staked assets.
• Create a system that meets all the requirements without compromising the core safety and liveness properties of the system.

• Chapter 6: Introducing Bitcoin

• Bitcoin is quite unstable and highly volatile.
• PoW concept: the money is created by broadcasting the solution to a previously unsolved computational problem. PoW is used to secure the blockchain. This is a proof that enough  computational resources have been spent in order to build a valid block.
• The PoW problem, also known as the partial hash inversion problem consumes a high amount of resources, including computing power and electricity. This process also secures the system against fraud and double-spending attacks while adding more virtual currency to the Bitcoin ecosystem.
• Hal Finney was the first person to receive Bitcoin from Satoshi Nakamoto.
• In the Bitcoin network, users have to wait for six blocks, which is equivalent to an hour, to get the right level of confidence that a transaction is final.
• Trustless refers to the distribution of trust between users, rather than a central entity.
• Network is owned collectively by its users instead of a single entity. The more users use the network, the more valuable it becomes.
• The double spending problem arises when a user sends coins to two different users at the same time and they are verified independently as valid transactions. The double spending problem is resolved in Bitcoin by using a distributed ledger (the blockchain) where every transaction is recorded permanently.
• The sender enters the receiver's address.
• The transaction fee is calculated based on the size of the transaction and on the fee rate.
• The higher the transaction fee, the greater the chance that your transaction will be picked up as a priority and included in the block.
• Bitcoin transactions are serialized for transmission over the network and encoded in hex format.
• Public keys can be represented in an uncompressed or compressed format, and are fundamentally x and y coordinates on an elliptic curve.
• Transaction malleability has been solved with the so-called SegWit soft-fork upgrade of the Bitcoin protocol.
• The paper wallets can be stored physically as an alternative to the electronic storage of private keys.
• Transactions are not encrypted and are publicly visible on the blockchain.
• The mining is the process through which the blockchain is secured and new coins are generated as a reward for the miners who spend appropriate computational resources. 
• Mining is a process by which new blocks are added to the blockchain. Blocks, once mined and verified, are added to the blockchain, which keeps the blockchain growing.
• Transaction pool, also known as memory pools, are basically created in local memory (computer RAM) by nodes (Bitcoin clients) in order to maintain a temporary list of transactions that have not yet been added to a block.
• The time for transaction confirmation usually ranges from 10 minutes to over 12 hours in some cases.
• Bitcoin uses a simple stack-based language called Script. Scripting is quite limited and can only be used to program one thing: the transfer of bitcoins from one address to other addresses.
• In simple words, locking means providing Bitcoins to somebody, whereas unlocking means consuming the acquired Bitcoins.
• A coinbase transaction or generation transaction is always created by a miner and is the first transaction in a block. It is used to create new coins.
• Nonce is an arbitrary number that miners change repeatedly to produce a hash that is lower than the difficulty target.
• New blocks are added to the blockchain approximately every 10 minutes.
• Miners are rewarded with new coins if and when they discover new blocks by solving the PoW. 
• The rate of creation of new bitcoins decreases by 50% every 210000 blocks, which is roughly every four years.
• After 210000 blocks, the block reward halves. In November 2021 it halved down to 25 bitcoins. Currently, since May 2020, it is 6.25 bitcoins per block.
• Mining difficulty increases over time and bitcoins that could once be mined by a single-cpu laptop computer now require dedicated mining centers to solve the hash puzzle.
• The difficulty is calculated every 2016 blocks (around two weeks) and adjusted accordingly.
• The Bitcoins miners have to calculate hashes to solve the PoW algorithm.
• The hash rate basically represents the rate of hash calculation per second.
• As the core principle behind mining is based on the double SHA256 algorithm, over time, experts have developed sophisticated systems to calculate the hash faster and faster. 
• ASICs were designed to perform SHA-256 operations.
• Currently mining is out of the reach of individuals due to the vast amount of energy and money needed to be spent in order to build a profitable mining platform.
• Solo mining is not very profitable now.
• Core
• https://btc.com

• Chapter 7: the Bitcoin network and payment

• The Bitcoin network is a peer-to-peer (P2P) network where nodes perform transactions.
• There are different types of nodes on the network. The two main types of nodes are full nodes and simple payment verification (SPV) nodes.
• SPV nodes only download the headers of the blocks while syncing with the network.
• SPV clients are used to verify payments without requiring the download of the full blockchain.
• On a Bitcoin network, there are full clients (nodes), which perform the function of storing a complete blockchain. If you cannot run a full node, then SPV clients can be used to verify that particular transactions are present in the block by only downloading the block headers instead of the entire blockchain. At times, even running an SPV node is not feasible (especially on low-resource devices such as mobile phone) and the requirement is only to send and receive Bitcoin somehow. For tis purpose, wallets (wallet software) are used that do not require downloading even the block headers.
• Since version 0.10.0, the initial block download method named headers-first was introduced. This resulted in major performance improvement, and blockchain synchronization that used to take days to complete started taking only a few hours.
• The wallet software is used to generate and store cryptographic keys. It performs various useful functions, such as receiving and sending Bitcoin, backing up keys, and keeping track of the balance available. 
• Private keys are used by wallets to sign the outgoing transactions. Wallet do not store any coins, and there is no concept of wallets storing balance or coins for a user. In fact, in the Bitcoin network, coins do not exist; instead, only transaction information is stored on the blockchain (more precisely, UTXO, unspent outputs), which are then used to calculate the number of bitcoins.
• Paper wallets can be generated on line from various service providers such as https://bitcoinpaperwallet.com or https://www.bitaddress.org/
• Lightning network is a solution for scalable off-blockchain instant payments. It was introduced in early 2016 and allows off-blockchain payments.
• Innovation in Bitcoin: improvement proposals are usually made in the form of Bitcoin Improvement proposals (BIPs).
• Excellent ideas have emerged from research and innovation efforts related to Bitcoin.
• The Bitcoin network can only process approximately three to seven transactions per second which is a tiny number compared to Visa network which can process on average 24,000 transactions per second. PayPal can process approximately 200 transactions per second whereas Ethereum can process up to, on average 20.
• The Segregated Witness (SegWit): the key idea behind SegWit is the separation of signature data from transaction data (that is, a transaction Merkle tree), which results in the size of the transaction being reduced.
• Not only has the original Bitcoin evolved quite significantly since its introduction, but there are also new blockchains that are either forks of Bitcoin or novel implementations of the Bitcoin protocol with advanced features.
• Bitcoin cash (BCH) uses Proof of Work (PoW) as a consensus algorithm, and mining hardware is still ASIC-based.
• Bitcoin Gold is hard fork and uses the Equihash algorithm as its mining algorithm instead of PoW.
• Market orders means that as soon as the prices match, the order will be fulfilled immediately. Limit orders allow for buying and selling a set number of bitcoins at a specified price or better.

• Chapter 8: Bitcoin Clients and APIs

• The Bitcoin client can be installed from https://bitcoin.org/en/download
• A Bitcoin client is a piece of software that is responsible for generating private/public key pairs and facilitates Bitcoin payments using the Bitcoin blockchain.
• The Bitcoin source code can be downloaded and compiled if users wish to participate in the Bitcoin code or for learning purposes.
• Regtest mode (regression testing mode) can be used to create a local private blockchain for testing purposes.
• Using the HTTP REST interface available at https://bitcoincore.org/en/doc/0.19.0/rpc
• Blockchain info: https://blockchain.info/api
• BitPay: https://bitpay.com/api
• Block.io: https://www.block.io

• Chapter 9: Alternative Coins
• Alternative approaches to Bitcoin can be divided broadly into two categories, based on the primary purpose of their development. If the primary goal is to build a decentralized blockchain platform, they are called alternative chains; if the sole purpose of the alternative project is to introduce a new virtual currency, it is called an altcoin.
• Namecoin: the primary purpose is to provide decentralized naming and identity services instead.
• Ethereum classic is the old chain and Ethereum is the new chain after the fork. Such a contentious hard fork is not desirable.
• Altcoins must be able to attract new users, trades and miners.
• Currency gains its value, especially in the virtual currency space, due to the network effect and its acceptability by the community.
• The power is shifting toward miners or mining pools who can afford large-scale ASIC farms. This power shift challenges the core philosophy of the decentralization of Bitcoin.
• PoW does have various drawbacks, and the biggest of all is energy consumption. It is estimated that the total electricity consumed by Bitcoin miners currently is more than that of Greece at 59.61 Terawatt hash (TWh)
• Proof of Stake (PoS): users are required to demonstrate the possession of a certain amount of currency (coins), thus proving that they have a stake in the coin.
• In Bitcoin, the difficulty is adjusted every 2016 blocks.
• Privacy and anonymity: as the blockchain is a public ledger of all transactions and is openly available, it becomes easy to analyze it. This is a big concern from a privacy point of view. Various proposals have been made to address the privacy issue in Bitcoin. These proposals fall into three categories: mixing protocols, third-party mixing networks and inherent anonymity.
• Dandelion is a proposal that aims to make transactions on a Bitcoin network untraceable. The Dandelion protocol is composed of an anonymity phase and a spreading.
• Colored coins: coloring a bitcoin refers colloquially to updating it with some metadata representing a digital asset (smart property). The coin still works and operates as a Bitcoin, but additionally carries some metadata that represents some assets.
• Colored coins can be used to represent a multitude of assets, including, but not limited to, commodities, certificates, shares, bonds and voting.
• Counterparty is another service that can be used to create custom tokens.
• Counterparty works based on the same idea as colored coins by embedding data into regular Bitcoins transactions, but provides a much more productive library and a set of powerful tools to support the handling of digital assets.
• Counterparty allows the development of smart contracts on Ethereum using the Solidity language and allows interaction with the Bitcoin blockchain.
• Development of altcoins: Altcoin projects can be started very quickly from a coding point of view by simply forking the Bitcoin or another coin's source code, but this is probably not enough. Usually, the code base is written in C++, as was the case for Bitcoin, but almost any language can be used to develop coin projects; for example Golang or Rust.
• Reward halving rate: Bitcoin is halved every 4 years and now is set to 12.5 Bitcoin.
• Total supply of coins: this number sets the total limit of the coins that can be ever be generated.In Bitcoin, the limit is 21 million, whereas in Dogecoin, it's unlimited.
• Token versus cryptocurrency: A cryptocurrency is a native coin for a standalone blockchain. In contrast, a token is a representation of the value of some asset.
• Initial Coin Offering (ICO) is a method for crowdfunding. The first successful ICO was that of Ethereum, which raised 18 million USD in 2014. A recent success is Tezos, which made 232 million USD in a few weeks. Another example is Filecoin, which raised more than 250 million USD. A more recent example is EOS, which raised a record of over 4 billion USD.
• Ethereum has become a platform of choice for ICOs due to its ability to create new tokens and with the ERC20 (Ethereum Request for Comments)standard, it has become even more accessible.
• Cryptocurrencies are a very attractive area for research.
• Chapter 10: Smart Contracts

• Smart contracts are now on going and intense area of research in the blockchain space.
• Smart contracts can bring many benefits such ad increased security, cost-saving and transparency to industries (especially the finance industry).
• Nick Szabo forts theorized smart contracts in the 1990's.
• A smart contract is a secure and unstoppable computer program representing an agreement that is automatically executable and enforceable.
• Code is the law.
• Certain inputs that need to be provided by people can and should be also automated. Oracles can be used for that purpose.
• English law recognized crypto assets as traceable property and smart contracts as enforceable agreements. This announcement was made by the UK Jurisdiction Taskforce (UKJT) (https://technation.io/news/uk-takes-significant-step-in-legal-certainty-for-smart-contracts-and-cryptocurrencies)
• If humans and machines can both understand the code written in a smart contract, it might become acceptable in legal situations, as opposed to just a piece of code that no one understands except for programmers.
• Legal Knowledge Interchange Format (LKIF)
• Smart contract have the following properties:
• automatically executable
• enforceable
• deterministic
• semantically sound
• unstop-able
• Ricardian contracts (https://iang.org/papers/fc7.html) fundamental: write a document that is understood and accepted by both a court of law and computer software.
• Consider a smart contract as a standalone entity that is capable of encoding legal prose and code (business logic)
• Solidity is a language that has been introduced with the Ethereum blockchain to write smart contracts.
• Tibco StreamBase product is a Java based system used for building event-driven, high frequency trading systems is an equivalent to DApp (Decentralized App)
• An inherent limitation with smart contracts is that they are unable to access any external data. The concept of oracles was introduced to address this issue. An oracle is an off-chain source of information that provides the required information to the smart contracts on the blockchain.
• The limitation with smart contracts is that they cannot access external data because blockchains are closed systems without any access to the real world.
• An oracle can be defined as an interface that delivers data from an external source to smart contracts.
• TLS notary provides a piece of irrefutable evidence to an auditor that specific web traffic has occurred between a client and a server. In is based on TLS (Transport Layer Security).
• To prove the authenticity of the data retrieved by oracles from external resources, attestation such as the TLSNotary are used.
• Ledger proof, Ledger Nanao S: the primary purpose of these devices is a secure hardware cryptocurrency. These devices run a particular OS called Blockchain Open Ledger Operating system (BOLOS)
• A trusted hardware assisted proof is Town Crier (https://www.town-crier.org) which provides an authenticated data feed for smart contracts. It uses Intel SGX to provide a security guarantee that the requested data has come from an existing trustworthy source.
• Various other blockchain platforms support smart contracts such as Monax, Lisk, Counterparty, Stellar, Hyperledger fabric, Axoni core, Neo, EOSIO and Tezos.
• DAO: Decentralized Autonomous Organization was a smart contract written to provide a platform for investment.
• DAO: due to a bug, called the reentrancy bug, it was hacked in June 2016. An equivalent to approximately 3.6 million ether was siphoned out of the DAO into another account. This incident resulted in a hard fork on the Ethereum blockchain, which was introduced to recover from the attack. Subsequently, resistance against this hard fork resulted in the creation oof Ethereum Classic, where a large number of users decided to keep the mining on the old chain.
• The security of smart contracts is an area of deep interest for researchers.
• Ricardian contracts are concerned with the definition of the contract, whereas smart contracts are geared toward the actual execution of the contract.

Chapter 11: Ethereum 101

• Ethereum has its own decentralized and distributed ecosystem that uses Swarm for storage and the Whisper protocol for communication.
• USDT token (Tethers) using the ERC 20 standard.
• Merkle-Patricia trees are used in the Ethereum blockchain.
• Ethereum with its Serenity release will soon transition to a PoS based consensus algorithm.

• DeFi

• https://defipulse.com

• Des liens nouveaux et intéressants 

• https://steemit.com
• https://ipfs.io
• https://identity.foundation
• https://openbazaar.org
• https://www.wireshark.org

• Acronymes

• AML: Anti Money Laundering
• BFT: Byzantine Fault Tolerance
• CAP Theorem : Consistency, Availability and Partition
• DAO: Decentralized Autonomous Organization
• EVM : Ethereum Virtual Machine
• ECC: Elliptic Curve Cryptography
• KYC: Know Your Customer
• Nonce: a nonce is a number that is generated and used only once.
• Merkle root: In a blockchain block, it is the combined hash of the transactions in the block
• PBFT: Practical Byzantine Fault Tolerance

• Translation

• escrow: dépôt
• unredeemable: non réclamable
• tumbler: acrobate