Fundamentals of Blockchain Technology...

Some examples of applications with a strong foundation on blockchain technology...

Blockchain applications are all the rage these days. The literal translation of this anglicized term, Blockchain, is blockchain.

Blockchain is the technology that eliminates the usual intermediaries that exist in classic economic transactions. The process liberalizes controls and it is the users themselves who supervise the exchange.

What is the process that emerges with the blockchain revolution?

For example: An individual wants to send money to another individual, this transaction is represented as a block in the network. This block is then transmitted to all nodes or users in the network and is approved by all users in the same network. This block, finally, is added to the blockchain that exists in that network which provides an immutable and transparent record of the transactions, concluding the process with the arrival of the money to the individual in question, of course, that this is one of the many examples.

Why is blockchain technology generating so much interest?

The possibility of blockchain technology being applied to other aspects beyond the economy has increased the interest in this technological revolution. In addition, the fundamental characteristics of immutability, transparency and de-centralization that the Blockchain provides, give it that character of robustness and security, which makes this new technology more reliable, while calling into question the usual and spurious methods of banking institutions.

At first this process was seen as a threat by the banks. But the commitment to a transformation in the logic of transactions has forced banks to pay more attention to the development of this technology. This is why the usual transaction methods, characterized by strong centralization and the need for the bank to act as an intermediary, are losing interest with the arrival of a technology that will revolutionize the way we know today's economy.

Open and decentralized system

The fact that it is an open and decentralized system where security is a necessity that must take precedence above all else generates an increase in confidence among users and a clear commitment to the use of this method.

Leading companies are starting to use these applications for different utilities; from the consolidation of a fully public, transparent and digitized ledger to the efficient storage of data or the tracking of shipments are just some of the most innovative applications that blockchain provides.

The development of blockchain technology is still to be seen, the main applications that we can observe today are those related mainly to the so-called cryptocurrencies, the proliferation of Bitcoin or Ethereum as alternative payment methods to ordinary money is already a reality. By 2017, it was estimated that virtual money moved more than $100 billion which indicates that economic and financial digitalization is here to stay.

Some examples of applications with great foundation on blockchain technology.

There are many applications that can be given to the blockchain, the possibilities can be endless. Although at present its functionality is highlighted by the use that is made of it for economic transactions, it is true that different institutions or companies find in this applicability some novel ideas that can be practiced in other areas. The following are seven examples of technological applications that are being used from blockchain.

1. Cloud storage

Cloud storage from blockchain, for example, allows the creation of nodes in different geographical locations that are able to withstand the failure of any server. This decentralization of information allows an integration of data that constitutes the overcoming of one of the most challenging challenges of technologies: the longevity of data.

2. Digital identities

In addition to the danger of digital identity theft in recent times, the blockchain provides a single, secure and immutable system that is the optimal solution to the problem of identity theft.

3. Data registration and verification

Another important point is registration and data verification. This process, often subject to hacking, could be decentralized to prevent other interests from interfering, thus establishing a new, more secure registration method for users.

4. Smart contracts

With the emergence of cryptocurrencies, there is also the rise of so-called smart contracts. These agreements can be fulfilled automatically, since they are implemented by means of a computer program and their fulfillment is not subject to interpretation by any of the parties. This reduces time and costs.

5. Supply chains

Blockchain will also be important in logistics management. The interest it poses for supply chains is focused, above all, on the possibility of an improvement in the supervision of food chains or in the tracking of production. This is why countries such as the United Kingdom already use 22% of such applications.

6. Automated security

The same goes for automated security; the incorruptibility of the blockchain allows the information required to be obtained without paying attention to security flaws that can result in data theft. In addition, the surveillance system can be used throughout the day without the possibility of the server going down.

7. Voting system

Finally, in an increasingly digitized world, some nations consider the blockchain as a new way of approaching democracy; obtaining from this application a new framework on which to regulate, for example, the voting system. Although some cybersecurity experts believe that blockchain cannot yet ensure the security of electronic voting, U.S. states such as West Virginia have already implemented this methodology.

(The fundamental characteristics of immutability, transparency and de-centralization that the Blockchain brings, give it that character of robustness and security, which makes this new technology, more reliable, while calling into question, the usual and spurious methods of banking entities)...

Alejandro O. Asharabed Trucido

Neura.Blockchain@aol.com

+54911 5665 6060

Buenos Aires, 2021, 28 de julio

What is Blockchain and how does it work?...

From one day to the next, Blockchain technology seems to have appeared in our lives and promises to revolutionize everything as we know it. But, beyond the promising practical application it offers us, this blockchain-based technology has not appeared out of nowhere.

Before even considering its feasibility, cryptographic technology (as a security method based on encrypting data to unauthorized recipients) has been researched for years: at first exclusively by the military and governments, later in algorithm research that developed the public key signatures and electronic signatures we know today. Thus, we arrived in the 1990s, a time when various computer projects appeared that sought interaction between users without the need for intermediaries and preached freedom of information.

What is Blockchain?

Blockchain is, by way of simplification, a digital ledger (ledger in English) that allows, through the use of computers, the storage of updated information permanently, with all copies of all computers being synchronized with each other.
A blockchain is a registry, like a ledger containing digital data, which is distributed or shared among many people at the same time. It can only be updated by the consensus of the majority of participants in the system.

When one person sends money to another, that transaction is represented in the Blockchain network as a block, which is transmitted to very diverse places within this financial network. At that moment, other users appear on the scene, who are the ones who approve that that transaction is valid, and automatically after it is approved it is added to the chain, making its transparency clear. Once the block has been correctly tied up, the receiver has his money.

Does it really give confidence that a group of strangers inspect and validate the transactions you make?

It may raise concerns that there is no centralized institution that organizes it. Currently all the platforms we make use of over the internet are backed by a central authority that we trust (bank accounts, Whatsapp, Google, etc.). In Blockchain, in order to forge an entry in a blockchain it would be necessary to simultaneously convince more than half of the people involved in the digital record we are referring to. Which is complicated to say the least.

No one knows who is who within the Blockchain network, only a transfer from one digital account to another is observed. In addition, as it is a decentralized network without a main computer, called P2P networks, everything is accounted for without the ability to be hacked.
In short, Blockchain represents a collaborative ledger written by consensus. The distribution of this consensus results in an incorruptible record of events that are recorded.

The Blockchain network is not always linked to money. There is, for example, the token, which is the representation of an information hosted on the network, so it can be any asset, good or service, not necessarily financial. Token transfers travel encrypted, so their distribution is secure and their content is not revealed, whether they are bitcoins or a car rental.

What characterizes the Blockchain system

A main feature of the Blockchain system is based on privacy, respecting identity thanks to the use of cryptographic keys. Moreover, since it is not allowed to be altered, it is a system that provides transparency in its operations. For this reason, it is considered to be the most important trust-giving technology in history, to the point of making it possible to dispense with the use of intermediaries in the registration of transactions.
This leads us to the decentralization it implies, as it does not require any type of institution to regulate or approve its operation. 

Moreover, this feature has always been one of the ideological pillars that have accompanied this project. Jeff Garzik, a renowned developer, said about Satoshi Nakamoto, who is credited with the creation of the Bitcoin system, "Satoshi published an open source system so that no one needed to know who he was or what knowledge he had. Open source software makes it impossible to hide secrets. The source code speaks for itself."

At the same time, it reduces logging and data control tasks. Blockchains avoid duplicate logging, only one log regardless of the number of participants.
Decentralization and not having a central node where all the information is agglutinated means that the intervening parties have full confidence in this technology. Its immediacy minimizes the counterparty risk produced in other transactions, where the payment commitment takes several days to be executed, thus avoiding risks of non-payment, bankruptcy or fraud during the payment process.

On the other hand, Blockchain has a scalability problem, the transaction speed is slow (due to the time it takes for each block to close) and the size of its database is growing exponentially. Currently the size of the blocks is over 100Gb, which makes its use at a domestic level not viable.
At the same time, we find a lack of regulation by legislative systems, giving rise to uncertainty in its use as it is not known what kind of regulations States and Central Banks will undertake in the future regarding this technology.

#Blockchain #Criptos #DeFi #Altcoins 

Alejandro O. Asharabed Trucido

Neura.Blockchain@aol.com

+54911 5665 6060

Buenos Aires, 2021, 28 de julio

What is the Blockchain?...

To be perfectly honest, knowing what blockchain, or blockchain technology, is is not going to help you become a better trader or make more profit. However, knowing at least superficially what it is is going to help them to: 

1) Understand the fundamentals of the assets that will be executed with traders. A crude analogy would be that of a stock trader who does not know what a company's stock is or what it represents.

 
2) Familiarize themselves with the elements of a blockchain that they will use, such as sending and receiving cryptocurrencies, sharing their public key, safeguarding their private key, etc. 

3) Understand how this new asset class works, identify the elements from which its value could be derived and create your own opinion of the future of this industry. Here is a definition that is simple to understand and encompasses the main characteristics of this technology. Simplistically, blockchain can be defined as: 
A record of transactions grouped into blocks, which are secured by cryptography and is usually distributed.

If this definition seems a bit complicated to you, you could also understand it as follows:

Blockchain is like a giant Excel, or a giant notebook, that everyone has, where everyone can write, that is always updated, but that no one can modify what is already written.

Let us now look at each of the elements of the definition separately and in a very simplified way to better understand each other. It is a record of transactions since all the movements that occur at all times and all over the world are written there. If Alice sends money (or in this case cryptocurrencies) to Bruno, this act is recorded. If Bruno then sends it to Carlos, this is also recorded. Everything is always recorded. After a certain time, 10 minutes in the case of Bitcoin, all valid transactions are grouped into a block that, once created, can never be modified. Every 10 minutes on average a new block is created, which refers to the previous block, forming a chain. 

This entire process, from sending cryptocurrencies to "immortalizing" transactions in blocks, is secured by cryptography. 

Among the most relevant elements are public-private key pairs, elliptic curve cryptography, hashes and Merkle Trees. These are more advanced topics beyond the scope of this section.

What are Cryptocurrencies?

Just like the answer to what is blockchain, knowing the answer to what are cryptocurrencies is not going to make you a better trader, but it is preferable that you know it. Knowing what they are will help you understand how to send, receive, store, and safeguard your assets. Without further ado, here is one of the many definitions that cryptocurrencies can have:

Cryptocurrencies are a digital medium of exchange that uses cryptography to secure transactions.

This is an even broader definition than the one we saw previously for blockchain and this may be due to the fact that its development started only a few years ago. The first and best known cryptocurrency is Bitcoin, which was proposed in 2008 and launched in 2009. Little by little new cryptocurrencies were created until reaching the more than 2,000 that exist today. 

Cryptocurrencies are so new that even different central banks and international organizations such as the BIS, the IMF and the World Bank are still debating whether cryptocurrencies are really currencies, assets, commodities, securities... or perhaps a new asset class. 

Alejandro O. Asharabed Trucido

Neura.Blockchain@aol.com

+54911 5665 6060

Buenos Aires, 2021, 28 de julio

IMF, World Bank and BIS champion central bank digital currencies at G20...

A new report released by the triumvirate of global finance argues that central bank digital currencies will benefit worldwide development.

In a joint report, the International Monetary Fund (IMF), the World Bank and the Bank of International Settlements (BIS) have proposed to the G20 that a cross-border network of central bank digital currencies (CBDC), underpinned by efficient technological integration and proactive international cooperation, could be of significant benefit to the world economy.

The report focuses on broadening the horizon beyond central banks’ individual studies of CBDCs for domestic needs, emphasizing that it is crucial to coordinate work at a global scale and to find common ground between various national efforts to reap the full benefits of digital currency.

If tackled astutely, the IMF, the World Bank and the BIS believe that the creation of CBDCs could offer a “clean slate” that would enable the global financial system to significantly enhance the efficiency of cross-border payments.

The report paints a bleak picture of the current system for cross-border payments, which is beset by long transaction delays and high costs due to an excessive number of intermediaries operating across different time zones across the correspondent banking process.

Moreover, cross-border flows are often opaque and difficult to trace, presenting a problem for Anti-Money Laundering (AML) and combating the financing of terrorism (CFT) implementation. Over the past decade, the attenuation of cross-border banking relationships has left some countries struggling to integrate into the global financial system fully.

The report weighs the significant benefits that CBDCs could present for increased efficiency and enhanced economic inclusion against the potential global macro-financial implications and risks involved in the widespread use of CBDCs for cross-border flows.

These challenges include dealing with the sudden capital flow reversals enabled by more frictionless cross-border flows and the potential impact on countries’ ability to manage their exchange rates. If the foreign currency becomes easier to obtain, store and spend, widespread currency substitution could potentially undermine states’ monetary policy independence and pose risks to both issuing and receiving countries.

A worldwide push for CBDC issuance, the report notes, would therefore require tight integration of multiple CBDCs and uniformity of design choices, alongside specific measures designed to mitigate these macro risks.

The groundwork would not only be conceptual and design-focused but would imply coordinated strategies, standardized practices and a degree of structural integration, ranging from the creation of new international payment infrastructures to targeted policies. The latter, for example, could include introducing limits on foreign CBDC holdings or transfers.

Related: UK chancellor names CBDC on list of financial reforms for Treasury

In addition to extensive infrastructural cooperation on technological interoperability and payment system access, there would need to be a similar level of regulatory coordination, implying the alignment of supervisory and oversight frameworks for cross-border flows and the coordination of AML and CFT measures.

While most countries are studying or developing pilots for CBDCs, central banks have taken a wide variety of distinct approaches to CBDC design and have paced their research and development efforts differently. China’s digital yuan is well ahead of the international game, and multiple countries have piloted CBDCs for cross-border use, including France, Switzerland, Singapore and Bahrain, to name just a few.

Alejandro O. Asharabed Trucido

Neura.Blockchain@aol.com

+54911 5665 6060

Buenos Aires, 2021, July 18

How does Blockchain work?

In order to explain in a summarized way the functioning of Blockchain, first of all, it is necessary to know the main elements that integrate it. Thus, the main components of a blockchain system are the following: 

1.0) The blockchains where the transactions that take place on the network are noted. 

1.1) The blocks are sequentially linked to each other, through functions called hashes (cryptographic digests), forming a chain. Each block has a certain maximum capacity and is like a page of an accounting ledger, in fact it is the accounting ledger, practically infinite, in which everything that has been written can no longer be erased or altered, which gives it absolute immutability.

2.0) The nodes are simply the computers, i.e. each user, that store the copy of the accounting ledger, i.e. they store the blockchain. To be configured as a node, each computer must have the corresponding software and in case of being a permissive network, obviously with the relevant permissions. 

3.0) Digital wallets or wallets, which are mere applications or interfaces through which users make transactions and manage their digital identity (ID) in order to operate. It is a simple app that can be downloaded to the user's device, through which the private key and the public key with which each user can operate are available.

3.1) On the other hand, there are also so-called miners, especially in cryptocurrency networks, who are the nodes that authorize the addition of blocks to the chain and, to do so, they must solve a mathematical problem following a consensus protocol. 

For this effort (which involves having great capacity and using a lot of energy) they receive rewards in digital currency that come both from new coins, which are created by mining the transaction, and from the commissions paid by those who order the transactions. 

In cryptocurrencies, mining can primarily use Proof of Work (PoW) or Proof of Stake (Proof of Stake) systems.

The operation of a common blockchain transaction begins with the sending of a digital asset from one digital wallet or wallet to another digital wallet of another user. 

These transactions have to be endorsed by several nodes and grouped with other transactions and then be taken by the miners as a job that they have to solve in exchange for a reward. 

The miners choose a set of transactions that can be different for each group of miners and compete with each other to obtain what is called a value (nonce) that solves the puzzle or mathematical challenge that authorizes the miner who solves it, (logically in a mechanized way through his computational capacity) to propose his block with the transactions that this block contains, to be added to the blockchain. 

This proposed block also includes the identification and hash of the previous block, thus establishing the linearity of the chain. All blockchains are distributed, i.e., they run on computers volunteered by people around the world, so there is no central database that can be attacked. A potential attacker would have to have at least 51% of the network to try to achieve his goal. 

For example, in the Bitcoin Blockchain, every ten minutes, all transactions made are checked, sorted and stored in a block that is joined to the previous block, thus creating a chain. If you want to steal a bitcoin you have to rewrite the entire blockchain in full view of everyone, which is practically impossible.

The encryption system is essential in blockchain. In 1976, Whitfield Diffie and Martin Hellman created the algorithm that bears their name, with which they proposed to break encrypted keys into two keys, so that there would be a public and a private one. The public key can be used to encrypt a message, but the private key is needed to decrypt it. 

These authors, together with Ralf Merkle, creator of the Merkle Trees and Ron Rivest, Adi Shamir and Leonard Adleman, creators of the RSA algorithm that allows the encryption and decryption of messages, constitute the group of creators of public key cryptography.

To make fraudulent modifications to the operations would require launching a simultaneous computer attack on the various databases. If, for example, an attempt were made to modify the contents of one of the blocks, the rest of the network devices would respond instantly, corroborating that the altered data does not match the rest and reverting it to the original. In this way, a healthy record is kept of operations in cryptocurrency networks and problems such as double spending or other malicious actions are avoided. 

Alejandro O. Asharabed Trucido

Neura.Blockchain@aol.com

+54911 5665 6060

Buenos Aires, 2021, July 18

What is Blockchain?

This was the usual question asked by everyone.... When this enigmatic anglicism was first heard, it was from the day Satoshi Nakamoto, the father of Bitcoin, published his White Paper on October 31, 2008, the day the world's first cryptocurrency based on the Blockchain was born. But it was not until, between 2014 and 2016, that this term or anglicism began to become popular in certain circles and business areas, defining itself, exponentially, towards a growing diversity of social, economic and institutional environments.

Blockchain, translatable as "blockchain", is a technology that is part of the field of so-called distributed ledger technologies or DLT (Distributed Ledger Technologies). It allows managing data, orders, transactions, assets and tokens, through an ingenious distributed or decentralized registration system that is recorded in blocks of information that are sequentially concatenated creating a chain of blocks or immutable and unalterable records, collaboratively shared among all members of each blockchain network, and which are verified by these members of the network, acting as "nodes" of the same.

In this way, a registration procedure is created, which works by means of consensus cryptography, equivalent to a ledger, but in this case digital, of which there are as many identical copies as members of the network. The cryptographic consensus used ensures that there is a single auditable and unmodifiable version of the data stored and of each movement or transaction, which introduces a sort of decentralization of the concept of trust, now based on P2P (peer to peer) collaborative relationships that do not require the existence of a central authority, as has been the common denominator to date.

In contrast to the traditional centralized databases housed in a central institution or on its servers, a distributed, decentralized, shared and replicated database can be created using blockchain, which can be public or private, permissive (accessible only to those who are admitted as members of the network, as occurs with a private or closed blockchain that could be created, for example, by a business group, a government organization or a network of military bases) or non-permissive (freely accessible to any user who wishes to do so by installing the appropriate free software).

The data or transactions recorded in the distributed ledger or accounting database must be immutable, auditable, have cryptographic protection and be equipped with a system for verifying their veracity, a task performed by the so-called validator nodes. This procedure allows the registration of different transactions on a decentralized basis, facilitating the exchange of information between parties in an efficient, open and verifiable manner.

Blockchain is known as the Internet of Value, also the Internet of trust, as opposed to the current Internet of information, since it allows the transfer of value or digitized assets between users, as opposed to the classic Internet that only allows sending information or copies of assets. A simple example can help to understand this difference: Currently, copies of a photograph can be sent from one device to all desired users, while with blockchain, ownership of the photograph can be transmitted to another user. The same idea works for countless applications that are currently being developed: transfer of property titles, financial assets, etc.

An essential element of blockchain is that it allows users who do not fully trust each other to maintain a consensus on the existence, status and evolution of a series of shared factors; in other words, the network itself acts as a guarantee of faith, introducing systems of trust between strangers. From a technical point of view, this trust and consensus-based system is built from a global network of computers managing a gigantic database.

There are currently several blockchain networks operating worldwide, somewhat like different operating systems. For example, bitcoin, the famous cryptocurrency, which is configured as the first effective and globally widespread application of blockchain, is one of them. Another of the most prominent is Ethereum, which is formed by thousands of nodes distributed around the world and that form a platform on which you can move or develop many specific applications, given its versatility, being especially useful for the development of so-called Smart contracts, with the ERC-20 protocol for the creation and exchange of tokens.

In fact Blockchain, is the network that is being implemented in the world, of semi-public or public character requiring the identification of the participants and multisectorial, in which companies of all types and sectors participate, from small start-ups to the majority of technology companies, consulting firms, recognized law firms, various universities, banks and private and public institutions.

Alejandro O. Asharabed Trucido

Neura.Blockchain@aol.com

+54911 5665 6060

Buenos Aires, 2021, July 18

The Stellar Consensus Protocol...

Un modelo federado para el consenso a nivel de Internet...

(David Mazieres, Fundación de Desarrollo Estelar)

Este documento introduce un nuevo modelo de consenso llamado acuerdo bizantino federado (FBA). Logística de Amazon logra Solidez a través de segmentos de quórum: decisiones de confianza individuales tomadas por cada nodo que juntas determinan Quórumes a nivel de sistema. Los segmentos unen el sistema de la misma manera que las decisiones de peering y tránsito de las redes individuales ahora unifican Internet.

También presentamos el Stellar Consensus Protocol (SCP), una construcción para FBA. Al igual que todos los protocolos de acuerdos bizantinos, SCP no hace suposiciones sobre el comportamiento racional de los atacantes. A diferencia de los bizantinos anteriores modelos de acuerdo, que presuponen una lista de miembros aceptada unánimemente, SCP disfruta de membresía abierta que promueve el crecimiento orgánico de la red. En comparación con descentralizado (prueba de trabajo) y (prueba de participación) esquemas), SCP tiene modestos requisitos informáticos y financieros, reduciendo la barrera de entrada y potencialmente abriendo los sistemas financieros a nuevos participantes.

Conceptos de CCS: •Seguridad y privacidad → Seguridad de sistemas distribuidos; Protocolos de seguridad; Palabras y frases clave adicionales: tolerancia a fallos bizantinos, sistemas asíncronos

1. INTRODUCCIÓN: 

La infraestructura financiera es actualmente un lío de sistemas cerrados. Brechas entre estos sistemas significan que los costos de transacción son altos [Provost 2013] y el dinero se mueve lentamente a través de fronteras políticas y geográficas [Banning-Lover 2015; CGAP 2008]. Éste La fricción ha reducido el crecimiento de los servicios financieros, dejando a miles de millones de personas desatendidas financieramente [Demirguc-Kunt et al. 2015].

Para resolver estos problemas, necesitamos una infraestructura financiera que apoye el tipo de crecimiento orgánico e innovación que hemos visto en Internet, pero aún así garantiza la integridad de las transacciones financieras. Históricamente, hemos confiado en altas barreras de entrada a garantizar la integridad. Confiamos en las instituciones financieras establecidas y hacemos todo lo posible para regular ellos. Pero esta exclusividad entra en conflicto con el objetivo del crecimiento orgánico. Demandas de crecimiento Participantes nuevos e innovadores, que pueden poseer solo modestas finanzas e informáticas. Recursos.

Necesitamos una red financiera mundial abierta a cualquier persona, para que las nuevas organizaciones puede unirse y extender el acceso financiero a las comunidades desatendidas. El desafío para tales Una red se asegura de que los participantes registren las transacciones correctamente. Con una barrera baja Para ingresar, los usuarios no confiarán en que los proveedores se vigilen a sí mismos. Con alcance mundial, No todos los proveedores confiarán en una sola entidad para operar la red. Una alternativa convincente es un sistema descentralizado en el que los participantes juntos garanticen la integridad al acordar la validez de las transacciones de cada uno. Dicho acuerdo depende de un Mecanismo para el consenso mundial.

  

Este artículo presenta el acuerdo bizantino federado (FBA), un modelo adecuado para consenso mundial. En FBA, cada participante conoce a los demás que considera importantes. Espera a que la gran mayoría de esos otros acuerden cualquier transacción antes considerando la transacción liquidada. A su vez, esos participantes importantes no están de acuerdo. a la transacción hasta que los participantes que consideran importantes también estén de acuerdo, y así en. Eventualmente, una cantidad suficiente de la red acepta una transacción que se vuelve inviable. para que un atacante lo haga retroceder. Solo entonces los participantes consideran la transacción sentado. El consenso de FBA puede garantizar la integridad de una red financiera. Su control descentralizado puede estimular el crecimiento orgánico.

Este documento presenta además el protocolo de consenso Stellar (SCP), una construcción para FBA. Demostramos que la seguridad de SCP es óptima para un protocolo asíncrono, ya que Acuerdo de garantías bajo cualquier escenario de falla de nodo que admita tal garantía.

También mostramos que SCP está libre de estados bloqueados, en los que el consenso ya no lo es. Posible: a menos que las fallas de los participantes hagan imposible satisfacer las dependencias de confianza. SCP es el primer mecanismo de consenso demostrablemente seguro que disfruta de cuatro propiedades clave simultáneamente:

— Control descentralizado. Cualquiera puede participar y ninguna autoridad central dicta qué aprobación se requiere para el consenso.

— Baja latencia. En la práctica, los nodos pueden llegar a un consenso en escalas de tiempo que los humanos esperan. para transacciones web o de pago, es decir, unos segundos como máximo.

— Confianza flexible. Los usuarios tienen la libertad de confiar en cualquier combinación de partes que Considerar oportuno. Por ejemplo, una pequeña organización sin fines de lucro puede desempeñar un papel clave en mantener mucho más grande. instituciones honestas.

— Seguridad asintótica. La seguridad se basa en firmas digitales y familias de hash cuyas Los parámetros se pueden ajustar de manera realista para proteger contra adversarios con una potencia informática inimaginablemente vasta.

SCP tiene aplicaciones más allá de los mercados financieros para garantizar que las organizaciones funcionen Funciones importantes honestamente. Un ejemplo son las autoridades de certificación (CA), que literalmente Mantenga las llaves de la web. La experiencia demuestra que las CA firman certificados incorrectos que obtienen usado en la naturaleza [Microsoft 2013; Langley 2015]. Varias propuestas abordan este problema a través de la transparencia de los certificados [Kim et al. 2013; Laurie et al. 2013; Basin et al. 2014; Melara et al. 2014]. La transparencia de certificados permite a los usuarios examinar el historial de certificados emitidos para una entidad determinada y detectar intentos de CA de cambiar la clave pública de una entidad sin la aprobación de la clave anterior. SCP tiene el potencial para fortalecer el historial de certificados indeleble en el núcleo de la transparencia de certificados. Exigir un consenso global sobre el historial de certificados entre un grupo descentralizado de auditores haría más difícil dar marcha atrás y anular los certificados emitidos anteriormente.

  The next section discusses previous approaches to consensus. Section 3 defines federated Byzantine agreement (FBA) and lays out notions of safety and liveness applicable in the FBA model. Section 4 discusses optimal failure resilience in an FBA system, thereby establishing the security goals for SCP. Section 5 develops federated voting, a key building block of the SCP protocol. Section 6 presents SCP itself, proving safety and freedom from blocked states. Section 7 discusses limitations of SCP. Finally, Section 8 summarizes results. For readers less familiar with mathematical notation, Appendix A defines some symbols used throughout the paper. 

2. RELATED WORK 

  Figure 1 summarizes how SCP differs from previous consensus mechanisms. The most famous decentralized consensus mechanism is the proof-of-work scheme advanced by Bitcoin [Nakamoto 2008]. Bitcoin takes a two-pronged approach to consensus. First, it provides incentives for rational actors to behave well. Second, it settles transactions through a proof-of-work [Dwork and Naor 1992] algorithm designed to protect against ill-behaved actors who do not possess the majority of the system’s computing power. Bitcoin has overwhelmingly demonstrated the appeal of decentralized consensus [Bonneau et al. 2015]. 

  Proof of work has limitations, however. First, it wastes resources: by one estimate from 2014, Bitcoin might consume as much electric power as the entire country of Ireland [O’Dwyer and Malone 2014]. Second, secure transaction settlement suffers from expected latencies in the minutes or tens of minutes [Karame et al. 2012]. Finally, in contrast to traditional cryptographic protocols, proof of work offers no asymptotic security. Given non-rational attackers—or ones with extrinsic incentives to sabotage The Stellar Consensus Protocol 3 mechanism decentralized control low latency flexible trust asymptotic security proof of work ! proof of stake ! maybe maybe Byzantine agreement ! ! ! Tendermint ! ! ! SCP (this work) ! ! ! ! Fig. 1. Properties of different consensus mechanisms consensus—small computational advantages can invalidate the security assumption, allowing history to be re-written in so-called “51% attacks.” Worse, attackers initially controlling less than 50% of computation can game the system to provide disproportionate rewards for those who join them [Eyal and Sirer 2013], thereby potentially gaining majority control. As the leading digital currency backed by the most computational power, Bitcoin enjoys a measure of protection against 51% attacks. Smaller systems have fallen victim [crazyearner 2013; Bradbury 2013], however, posing a problem for any proof-of-work system not built on the Bitcoin block chain. 

  An alternative to proof of work is proof of stake [King and Nadal 2012], in which consensus depends on parties that have posted collateral. Like proof of work, rewards encourage rational participants to obey the protocol; some designs additionally penalize bad behavior [Buterin 2014; Davarpanah et al. 2015]. Proof of stake opens the possibility of so-called “nothing at stake” attacks, in which parties that previously posted collateral but later cashed it in and spent the money can go back and rewrite history from a point where they still had stake. To mitigate such attacks, systems effectively combine proof of stake with proof of work—scaling down the required work in proportion to stake—or delay refunding collateral long enough for some other (sometimes informal) consensus mechanism to establish an irreversible checkpoint. 

  Still another approach to consensus is Byzantine agreement [Pease et al. 1980; Lamport et al. 1982], the best known variant of which is PBFT [Castro and Liskov 1999]. Byzantine agreement ensures consensus despite arbitrary (including non-rational) behavior on the part of some fraction of participants. This approach has two appealing properties. First, consensus can be fast and efficient. Second, trust is entirely decoupled from resource ownership, which makes it possible for a small non-profit to help keep more powerful organizations, such as banks or CAs, honest. Complicating matters, however, all parties must agree on the the exact list of participants. Moreover, attackers must be prevented from joining multiple times and exceeding the system’s failure tolerance, a so-called Sybil attack [Douceur 2002]. BFT-CUP [Alchieri et al. 2008] accommodates unknown participants, but still presupposes a Sybil-proof centralized admission-control mechanism. 

Generalmente, la membresía en los sistemas de acuerdos bizantinos es establecida por una autoridad central. o negociación cerrada. Los intentos anteriores de descentralizar la admisión han abandonado algunos de los los beneficios. Un enfoque, adoptado por Ripple, es publicar una lista de miembros "iniciales". que los participantes pueden editar por sí mismos, esperando que las ediciones de las personas sean intrascendentes o reproducidas por una fracción abrumadora de participantes. Desafortunadamente, porque las listas divergentes invalidan las garantías de seguridad [Schwartz et al. 2014], los usuarios son reacios Editar la lista en la práctica y una gran cantidad de poder termina concentrado en el mantenedor de la lista de inicio. Otro enfoque, adoptado por Tendermint [Kwon 2014], es Base la membresía en la prueba de participación. Sin embargo, hacerlo una vez más vincula la confianza con los recursos. 4 D. Mazieres ' propiedad. SCP es el primer protocolo de acuerdo bizantino que da a cada participante la máxima libertad para elegir en qué combinaciones de otros participantes confiar.

Este documento continúa en el enlace:

https://www.stellar.org/papers/stellar-consensus-protocol 

Alejandro O. Asharabed Trucido

Neura.Blockchain@aol.com

+54911 5665 6060

Buenos Aires, 2021 de julio de 18