Consensus Décentralisé - Blockchains - Smart Contracts - Decentralized Consensus

Just as punk rock was repackaged as new wave, so was Bitcoin domesticated into blockchain.

It burst on to the popular imagination and the conference circuit. Visionary Don Tapscott affirmed, “I’ve never seen a technology that I thought had greater potential for humanity.” CEOs pointedly asked whether this was yet another disruptive technology. Their subordinates were set to investigate how it might work. And they found that it is all rather complicated.

Here is the IDATE 2016 DigiWorld Summit closing panel on Blockchain ; the whole conference was revolving around trust hence the title chosen before I engaged in a panel discussion with Consensys ' Joseph Lubin and Polychain Capital 's Olaf Carlson-Wee

Addressing the question of trust and blockchains requires to remember the context in which Satoshi Nakamoto’s white paper was issued in December 2008 : it was a few months after the subprime crisis and  the fall of Lehman Brothers, at a time when the trust in people was extremely challenged, both in their ability to process numbers without mistake, as well as their tendency to operate behind others back. It was a time where libertarians would trust machines and distrust people.

In a way, The Economist’s « The Trust Machine » could be interpreted as « trust the machines / distrust the middle people » 

As a distributed ledger that ensures both transparency and security, the blockchain is showing promise to fix the current problems of the supply chain. A simple application of the blockchain paradigm to the supply chain would be to register the transfer of goods on the ledger as transactions that would identify the parties involved, as well as the price, date, location, quality and state of the product and any other information that would be relevant to managing the supply chain.
The public availability of the ledger would make it possible to trace back every product to the very origin of the raw material used. The decentralized structure of the ledger would make it impossible for any one party to hold ownership of the ledger and manipulate the data to their own advantage. And the cryptography-based and immutable nature of the transactions would make it nearly impossible to compromise the ledger. Some experts already believe that the blockchain is unhackable.
Several efforts are already being made to leverage the power of the blockchain in improving the management of the supply chain. IBM has already rolled out a service that allows customers to test blockchains in a secure cloud and track high-value items through complex supply chains. The service is being used by Everledger, a firm that is trying to use the blockchain to push transparency into the diamond supply chain and thus help fix a market fraught with forced labor and tied to the funding of violence across Africa.
London-based Provenance is aiming to build trust across the supply chain from the source to the consumer by deploying Bitcoin- and Ethereum-based blockchains that enable companies to be more transparent on how they build their products. This includes disclosing everything about environmental impact, where the products were made and who they were made by.

Bitcoin, which had its genesis block mined in 2009, was the first digital currency to scale. While many early adopters took interest in bitcoin because of its promise of privacy, the digital currency failed to provide this benefit, as interested parties can examine the transactions recorded on bitcoin’s blockchain to get a sense of exactly what a person or entity has purchased.
In the years following bitcoin’s release, developers have created privacy-oriented digital currencies including Dash and Monero. Both of these use innovative technologies to help increase the chances of their users remaining anonymous.
Dash leverages a technique called "CoinJoin", in which several users put funds into the same transaction in order to increase the chances of privacy. Alternatively, Monero harnesses ring signatures to reduce the chance of detection.
Both of these cryptocurrencies have made great progress toward realizing the goal of anonymous transactions, and Monero has received widespread adoption in the dark web.
However, Zcash’s technology seemingly gives users the ability to enjoy an even greater level of privacy. By allowing users to remain anonymous, Zcash can provide them with greater fungibility.
This is because many digital currency transactions rely on the use of private keys – strings of letters and numbers that identify a user. An address can become attached to several transactions over time, making it easy for friends, family, marketers or even government authorities to learn more about a person’s purchasing trends.
And if a user’s private key is attached to certain transactions, some parties may refuse to accept his or her money. This is where Zcash comes in.

Ledger, the French company known for its range of bitcoin hardware wallets, has launched a new extension of its product line: the Ledger Blue.
Billed as "the most advanced hardware wallet on the market today", the Ledger Blue is a significant departure from the thumbdrive style of Ledger's previous products. With a 320 x 480 pixel screen (along with BlueTooth and near-field communication (NFC) capability), it's a handheld touchscreen device that can run a number of different applications.
In a video call, Ledger CEO Eric Larchevêque talked to CoinDesk about the product’s evolution, design philosophy and target market.

Enterprise blockchains — if successful — can bring some technical improvements but they will fail to deliver on their hype. Value proposition of enterprise blockchains is nuanced at best. If you don’t understand it, relax and wait until things crystallize.

Blockchain is an ambiguous term

Unfortunately, the “blockchain” word can mean very different things depending on whom you ask (cryptocurrencies community, banks, software vendors, regulators, and everyone in between). Wikipedia won’t help you much as there is an ongoing war between the multiple parties who want to own the word.

Still, the following characteristics seem to be common and safe to assume:

• Blockchain is a linked list (strictly speaking, it converges to a linked list)
• Each node can carry some data
• Each node has a cryptographic hash of the previous node (a form of pointer to its predecessor)
• Each node has a timestamp
• Multiple parties can independently append nodes to the list
• In case of conflicting appends to the list, there can be briefly a fork, and there is some mechanism to come to consensus on which branch is the valid one going forward; the non-valid branch(es) are discarded

Unfortunately, all other characteristics are optional and debatable.

Blockchain can be:

• Local or distributed; some companies claim to build and run their internal, local blockchains (please bear with me)
• Private or public; blockchains can be private to a group of participants, or open in the wild for anyone and their refrigerator to join
• Permissioned or permissionless; in a permissioned blockchain different participants are granted different level of access, there must be some form of authorization; in the permissionless blockchain any (potentially anonymous) entity can fully participate in a sense that all features are technically available, although participant impact can be practically limited by the free-market fees, computing power available and/or his “stake” in the blockchain
• Governed by central party or by decentralized voting
• Correctable or immutable; correctable blockchains allow to “fix mistakes” retrospectively; the immutable blockchains are append-only; their design protects from rewriting the history by making it exponentially expensive

SINGAPORE - The Monetary Authority of Singapore (MAS), the Singapore Exchange and eight banks have started a project to use blockchain technology for interbank payments, including cross-border transactions in foreign currencies.

MAS managing director Ravi Menon said at the Fintech Conference on Wednesday (Nov 16) that under the pilot system, banks will deposit cash as collateral with the MAS in exchange for MAS-issued digital currency.

The banks can later redeem the digital currency for cash.

The banks can pay each other directly with this digital currency instead of first sending payment instructions through the MAS. 

"This is an improvement over current large-value payment systems that are centrally operated," Mr Menon said. "It strengthens resilience and lowers cost."

The project, he added, marks teh first step in the MAS' exploration of ways to harness the potential of central bank-issued digital currency.

It is also just one of several initiatives that the MAS has embarked on in its quest to create a smart financial centre in Singapore, said Mr Menon at the conference, which is part of the week-long Singapore Fintech Festival.

For example, he also announced that the MAS was publishing on Wednesday its "regulatory sandbox" guidelines to encourage and enable experimentation of innovative technology to deliver financial products and services.

A blockchain platform developed by a group that includes more than 70 of the world's biggest financial institutions is making its code publicly available, in what could become the industry standard for the nascent technology.

The Corda platform has been developed by a consortium brought together by New-York-based financial technology company R3. It represents the biggest shared effort among banks, insurers, fund managers and other players to work on using blockchain technology in the financial markets.

Blockchain, which originated in the digital currency bitcoin, works as a web-based transaction-processing and settlement system. It creates a "golden record" of any given set of data that is automatically replicated for all parties in a secure network, eliminating any need for third-party verification.

Banks reckon the technology could save them money by making their operations faster, more efficient and more transparent. They are racing to build products using the technology that will generate new revenue, with dozens of patent applications filed for blockchain-based products by Wall Street's top lenders.

R3 says it hopes its platform will become the industry standard, although its intention is indeed for firms to build products on top of it.

"We want other banks and other parties to innovate with products that sit on top of the platform, but we don't want everyone to create their own platform ... because we'll end up with lots of islands that can't talk to each other," R3's chief engineer, James Carlyle, told Reuters.

"If we have one platform with lots of products on top, then we get something that's more like the internet, where we still get innovation but we can still communicate with each other."

Corda's code will be contributed on Nov. 30 to the Hyperledger project - a cross-industry project led by the non-profit Linux Foundation to advance blockchain technology by coming up with common standards.

Bitcoin's "most professional mining pool" has become its most controversial.

Following months of debate over how to scale bitcoin's transaction capacity, the conversation has become newly contentious as progress on much-hyped solutions continue to face the kinds of delays that perhaps should be expected when working with novel technologies.

This lack of progress (real or perceived) has so far most affected bitcoin's business community, many of which are dependent on technical improvements in the network for additional growth. Indeed, while bitcoin's primary development group has its share of detractors, the majority of startups and service providers continue to support Bitcoin Core and its work.

But if one, relatively new bitcoin mining pool has its way, a much anticipated scaling solution could be dead on arrival.

In recent weeks, China's ViaBTC became one of the first providers of mining software to switch its client from the official version provided by Bitcoin Core to an option provided by Bitcoin Unlimited, a rival development group that supports alternative methods of scaling that is focused on creating a more variable bitcoin block size.

But unlike Bitcoin Core, Bitcoin Unlimited does not have support for that developer group's signature scaling solution, Segregated Witness, a planned technical fix that would effectively make bitcoin's block size about 1.8 times larger than it is today by changing how information is counted toward this total.

Further, because the rules for Segregated Witness require 95% of bitcoin's hashing power to approve the transition, ViaBTC could effectively block its wider release. According to blockchain.info, over the past 24 hours, ViaBTC has accounted for 7.3% of the blocks discovered, though this has been as high as 9.6% in recent days.

Complicating matters is that despite a consensus of developers suggesting Segregated Witness is the best way to scale bitcoin, ViaBTC remains unconvinced.

Le 1er Forum parlementaire de la Blockchain a eu lieu le mardi 4 octobre à la Maison de la Chimie à Paris.

Au cours de cette matinée, près de 500 personnes ont assisté à plusieurs présentations, interventions et tables-rondes sur les principaux enjeux de la Blockchain, en présence de parlementaires experts de l'économie numérique et de représentants d'entreprises concernées par cette technologie révolutionnaire. Ils ont également pu échanger directement avec les intervenants.

Programme:

9h00 Ouverture par Jean Launay, député (PS) du Lot

9h15 – 10h30 Table-ronde « La Blockchain, aussi révolutionnaire qu’Internet ? »
- Luca Comparini, « Blockchain Leader » d’IBM ;
- Philippe Dewost, directeur adjoint chargé de l’économie numérique et du financement des entreprises à la Mission Programme d'Investissements d'Avenir au sein de la Caisse des Dépôts ;
- Virginie Duby-Muller, députée (LR) de la Haute-Savoie ;
- Mehdi Houas, président de Talan ;
- Nicolas Rivard, chief innovation officer d'Euronext ;
- Antoine Yeretzian, vice-président de La Chaintech.

10h30 – 11h Présentation de startups
- Christophe de Courson, Agentic France ;
- François Dorléans, Stratumn.

11h00 – 12h15 Table-ronde « Blockchain : ubérisation, disparition ou adaptation des tiers de confiance ? »
- Erik Arnaud, digital & data strategist de la MAIF ;
- Christian Buchel, directeur général adjoint, chief digital & international officer d’Enedis ;
- Hubert de Vauplane, avocat ;
- Corinne Erhel, députée (PS) des Côtes d’Armor ;
- Simon Polrot, avocat, fondateur d’Ethereum France ;
- Lionel Tardy, député (LR) de la Haute-Savoie.

12h15 Intervention d'Amal Taleb, vice-présidente du Conseil National du Numérique

12h30 Conclusion par Laure de la Raudière, députée (LR) d’Eure-et-Loir

12h45 Conclusion par Axelle Lemaire, secrétaire d’État chargée du Numérique et de l'Innovation

The German Federal Bank (Deutsche Bundesbank) and Deutsche Börse, one of the world's leading marketplace organizers for the trading of shares and other securities, have jointly presented a functional prototype for the Blockchain-based settlement of securities.
 
According to the official press release, this prototype is designed to provide the technical functionality for the settlement of securities in delivery-versus-payment mode for centrally-issued digital coins, as well is capable of settling basic corporate actions such as coupon payments on securities and the redemption of maturing securities. 

Carl-Ludwig Thiele, Member of the Deutsche Bundesbank's Executive Board commented: 

"With the blockchain prototype, the Deutsche Bundesbank and Deutsche Börse want to work together to find out whether this technology can be used for financial transactions, and if so, how this can be achieved. The Deutsche Bundesbank hopes that this prototype will contribute to a better practical understanding of blockchain technology in order to assess its potential.” 

The prototype is now a conceptual study, but both Deutsche Börse and the Deutsche Bundesbank plan to work on improving the prototype and drawing up a test concept in the next few months. Then this product will be used to analyse the technical performance and the scalability of this kind of blockchain-based application.

The bitcoin and blockchain world is in a bit of an investment slump.
Venture money flowing into startups working on cryptocurrencies or the technical principles underpinning them, generally known as blockchain technology, is getting harder to come by, according to data from trade publication CoinDesk. “It really seems like we’re in a slow phase with bitcoin and blockchain right now where people are mainly building infrastructure,” says Zavain Dar, a venture capitalist at Lux Capital who has taught classes on cryptocurrency at Stanford and has invested in Blockstream, one of the biggest companies in the sector.
What’s more, efforts to adapt blockchain tech to replace legacy financial systems by the world’s biggest banks seem to be hitting roadblocks. This week saw the departures of Goldman Sachs and Santander from one of the highest-profile attempts to create a consortium of financial institutions to work on the technology, called R3CEV.
It seems that both risk-loving venture capitalists and generally risk-averse banks are dialing back their investment in a technology that was supposed to change the world—but hasn’t, as Timothy B. Lee at Vox has pointed out.
Startups working on blockchain tech have raised $376 million so far this year, which is 17% less than the amount raised over the same period last year, according to CoinDesk’s latest quarterly research report. Funding declined every quarter in 2015, in stark contrast to three quarters of successive growth the previous year.

As many as seven of the original 42 members of the R3CEV banking consortium have yet to express interest in funding the startup's ongoing $150m funding round, leaked documents reveal.
Released on PasteBin this morning (and confirmed by sources close to the deal), the text details a list of the banks that have expressed interest in participating in the funding, how much each could invest and the names of seven banks that are alleged to have opted-out.
The list of banks includes names that have confirmed they are no longer participating in the consortium, including Banco Santander and Goldman Sachs, as well as those that were previously rumored to have withdrawn (such as Morgan Stanley and National Bank Australia) but that have yet to publicly respond.
New banks that have reportedly yet to submit a bid as part of the funding including JP Morgan, Macquarie Group and US Bancorp, though it is unclear if they are out of the consortium officially or if they have yet to confirm interest.

Cet article est la traduction intégrale en français du Mauve Paper rédigé par Vitalik Buterin décrivant la version 2.0 du protocole Ethereum et plus précisément la mise à jour Casper. Traduction réalisée par Jean Zundel, avec relecture d’Alex Kurth et Simon Polrot.

Au cours de la précédente décennie, des projets tels que Bitcoin, Namecoin et Ethereum ont démontré le pouvoir des réseaux de consensus crypto-économiques en apportant une nouvelle étape dans l’évolution des systèmes décentralisés en étendant leur portée, partant d’une simple fourniture de services de stockage de données et de messagerie, pour arriver à la gestion du back-office (base arrière) d’applications stateful (conservant leur état). Les applications proposées et mises en œuvre vont des systèmes de paiement universellement accessibles, tant financièrement que géographiquement, aux contrats financiers en passant par les marchés de prédictions, l’enregistrement de l’identité et de la propriété, la mise en place de systèmes de certificats plus sûrs et même la traçabilité des biens manufacturés au sein des chaînes d’approvisionnement.

Il subsiste néanmoins de sérieuses interrogations sur l’efficience du socle technique utilisé à cet effet. Comme chaque full node (nœud complet) du réseau doit maintenir à jour tout l’état du système et traiter chaque transaction, le réseau ne peut jamais être plus puissant qu’un seul ordinateur. Le mécanisme de consensus le plus souvent utilisé dans les systèmes existants, la proof of work (preuve de travail), doit consommer une très grande quantité d’électricité pour pouvoir fonctionner ; le réseau le plus important, Bitcoin, consommerait autant d’électricité que l’Irlande toute entière.

Ce document propose une solution à ce problème fondée sur la combinaison de proof of stake (preuve d’enjeu) et de sharding (fragmentation). La preuve d’enjeu n’est pas une idée nouvelle (elle date de 2011), mais ce nouvel algorithme présente des avantages substantiels en résolvant les problèmes des systèmes précédents, et en présentant même de nouvelles propriétés qui sont absentes dans la preuve de travail. La preuve d’enjeu peut être vue comme une sorte de « minage virtuel » : alors qu’avec la preuve de travail, les utilisateurs peuvent dépenser de l’argent réel pour acheter des ordinateurs réels qui consomment de l’électricité et produisent aléatoirement des blocs à une fréquence à peu près proportionnelle au coût, dans la preuve d’enjeu, les utilisateurs dépensent de l’argent réel pour acheter de la monnaie virtuelle dans le système puis utilisent un mécanisme interne au protocole pour convertir cette monnaie virtuelle en ordinateurs virtuels simulés par ce protocole pour produire aléatoirement des blocs à une fréquence à peu près proportionnelle au coût, reproduisant ainsi exactement le même effet mais sans la consommation d’électricité. La fragmentation n’est pas non plus une nouveauté car elle existe dans les bases de données distribuées depuis une décennie, mais la recherche appliquée à la blockchain est restée très limitée. L’approche de base consiste à relever le défi du passage à l’échelle par une architecture dans laquelle les nœuds d’un ensemble global de validateurs (dans notre cas créé par les cautions de preuve d’enjeu) sont assignés aléatoirement à des « shards » (fragments) spécifiques où chaque fragment traite les transactions en diverses parties de l’état, ceci en parallèle, assurant que le travail est réparti sur les nœuds au lieu d’être effectué par chacun.

Nous désirons atteindre les objectifs suivants :

1. Efficience par la preuve d’enjeu – le consensus doit être assuré sans le minage, réduisant ainsi considérablement le gaspillage d’électricité ainsi que le besoin continuel d’une importante génération d’ETH.
2. Génération rapide de blocs – la fréquence de génération des blocs doit être maximale, ceci sans compromettre la sécurité.
3. Finalité économique – une fois qu’un bloc est généré, après un certain temps, un état doit apparaître où l’essentiel des validateurs se sont « pleinement engagés » sur ce bloc, ce qui signifie qu’ils perdent l’intégralité de leurs dépôts en ETH (de l’ordre de 10 millions d’ETH) dans tous les historiques qui n’ont pas ce bloc. C’est un avantage car cela signifie que même la collusion d’une majorité ne peut pas effectuer d’attaque de type 51% sans détruire tout leur ether ; les stratégies par défaut des validateurs sont conçues dans une optique conservatrice, fondée sur leur volonté de s’engager sur des valeurs importantes tout en conservant un risque faible pour les validateurs honnêtes.
4. Passage à l’échelle – il devrait être possible de faire tourner la blockchain littéralement sans aucun nœud complet, c’est-à-dire dans une situation où tous les nœuds, y compris les validateurs, ne conservent pour travailler qu’une fraction minime des données de la blockchain et emploient des techniques inspirées des clients légers pour accéder au reste. De cette manière, la blockchain peut atteindre une vitesse de transactions bien supérieure à celle d’une machine unique tout en garantissant que la plate-forme peut fonctionner avec un nombre suffisamment grand d’ordinateurs portables grand public, préservant ainsi la décentralisation.
5. Communication inter-fragments – il faut qu’il soit extrêmement facile de faire interagir les applications situées sur différentes parties de l’état, stockées sur des nœuds différents, et de construire des applications réparties sur des portions différentes de l’état ; par exemple si l’usage d’une application donnée atteint un tel point que la puissance et la bande passante d’un unique nœud ne suffit pas à la tâche.
6. Résistance à la censure de calcul – le protocole doit être résistant aux tentatives par des collusion de majorités de validateurs à travers tous les fragments d’empêcher les transactions non désirées d’entrer dans la chaîne pour être finalisées. C’est le cas jusqu’à un certain point dans Ethereum 1.0 grâce à la « résistance à la censure par le problème de l’arrêt » mais nous pouvons amplement renforcer ce mécanisme en introduisant les notions d’ordonnancement garanti et de messages inter-fragments garantis.

Nous commençons par décrire un algorithme qui ne résous que les points (1) et (2), puis dans un deuxième algorithme nous traitons le point (3). Dans un troisième algorithme nous traitons ensuite partiellement les points (4) et (5) (la condition en étant une limite grosso modo proportionnelle au carré de la capacité de calcul d’un nœud dans le cas de (4) et un délai de 24 heures pour les messages inter-fragments, avec la possibilité de construire des messages plus rapides par une surcouche de dépôts dont le but est double, dans le cas de (5)). Des solutions plus complètes de (4) et de (5), ainsi qu’une résolution au moins partielle de (6), ne sont pas prévues pour la version 2.0 et sont à réétudier pour Ethereum 2.1 et 3.0.

Les constantes sont notées en capitales COMME_CECI et les valeurs en sont données à la fin de ce document. Les variables sont en minuscules comme_ceci, bien que parfois des noms à une seule lettre en majuscule comme X et B1 soient employées pour des variables.

While it's reasonable to assume that a world with real quantum computers will ruin traditional asymmetric encryption, perhaps surprisingly hash functions might survive.

That's the conclusion of a group of boffins led by Matthew Amy of Canada's University of Waterloo, in a paper at the International Association of Cryptologic Research.

The researchers – which included contributions from the Perimeter Institute for Theoretical Physics and the Canadian Institute for Advanced Research – looked at attacks on SHA-2 and SHA-3 using Grover's algorithm (a quantum algorithm to search "black boxes" - Wikipedia).

They reckon both SHA-256 and SHA3-256 need around 2166 “logical qubit cycles” to crack.

Perhaps counter-intuitively, the paper says the problem isn't in the quantum computers, but the classical processors needed to manage them.

When Bitcoin was first released, it brought an open financial system to the world. Anyone could connect without requiring permission from anyone else; anyone could extend and improve on it without permission.

However, it came with a drawback – privacy. Bitcoin allowed everyone to see the sending address, recipient address, and value of all transactions on the blockchain. Sure, they weren’t tied to a user (or computer) by default, but contamination was a possibility. People are, after all, only human. In contrast, Zcash automatically hides the sending address, recipient address and the value of all transactions – unless you have the viewing key.

The Zcash team was founded with privacy in mind: privacy for businesses; privacy for commerce. To be viable long-term, fungibility is needed – and without privacy, fungibility can’t exist. Bitcoin brought fungibility to the digital world, but Zcash is making it accessible. No longer do coins need to be tumbled; no longer do new addresses need to be generated for each transaction to ensure complete anonymity. It’s built in from the get-go.