Hello everyone,

I am very excited to be a part of the lecture by @alphafx. The lecture was short and straight to the point . I will be talking about Stellar Consensus Protocol

Stellar Consensus Protocol

In 2015, David Mazières published the Stellar Consensus Protocol in a whitepaper. It's a "federalised Byzantine arrangement scheme" that enables autonomous, leaderless computer networks to find a consensus on a resolution quickly and efficiently. SCP is used by the Stellar payment network to provide all users with a unified picture of the network's transaction history.

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However, before we go any further, we must define Stellar. The Stellar platform was launched in 2014 with the goal of using blockchain technology to make services more convenient.
Consensus is the next term to clarify. When we speak about ledgers, we must accept that the details collected is right. In the case of a centralised ledger, the agreement is straightforward: since the centralised power is the only person that has access to the ledger, it assumes that the information is correct, and consumers would believe. A distributed network, on the other hand, is a little more complex. Everyone may connect details to a shared blockchain, and anyone has the ability to check whether the information is real or false. As a result, the network must come to a consensus, or broad acceptance, that the data is right. This is a difficult challenge since the consumers and validators are anonymous and therefore untrustworthy.
How would untrustworthy people come to an agreement and affirm the authenticity of the details in the ledger? To determine how information is applied to the register, a protocol had to be developed.
Consensus protocols have a reputation for being difficult to understand. SCP is simpler than most, but it has a poor reputation due to the misunderstanding that "federated voting," as the whitepaper spends the first half of the document describing, is SCP. But it's not the case! Instead, it's a key component of the Stellar Consensus Protocol, which is detailed in the whitepaper's second half.
The basic operation of Stellar is close to that of other decentralised payment systems. It operates a decentralised cloud network with a distributed ledger that updates every 2 to 5 seconds across all nodes.

What is the mechanism behind Stellar's consensus method?

The Stellar network adds transactions to a shared, open, public ledger, a database usable for everyone in the world. Stellar has its own proprietary consensus system to achieve consensus on transactions easily and efficiently.
Any participant will add Stellar transactions to the global ledger, as long as these mini-networks (known as quorum slices) overlap, the overall Stellar network can agree on terms on which transactions are valid and can be applied to the global blockchain.

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The Stellar Consensus Protocol (SCP) allows people to come to an agreement without having to depend on a closed mechanism to keep track of financial transactions. SCP has a series of provable protection properties that prioritise safety over liveness, halting network development before agreement can be achieved in the event of partition or misbehaving nodes. SCP possesses four main characteristics at the same time: decentralised power, low latency, flexible confidence, and asymptotic security.

Here are a few ways to learn more about SCP:

• For a technical summary, start with the peer-reviewed paper on Stellar in SOSP 2019.
• Read the initial white paper to discover what there is to know regarding the Stellar Consensus Protocol.
• The entire whitepaper is longer and more difficult to read than a simplified SCP summary.

What Is Stellar Blockchain, and How Does It Work?

And as bitcoin made news over the last five years, other cryptocurrencies and blockchain networks also seen further remarkable gains and developer adoption.One of them was Stellar.

The value of Lumen, Stellar's cryptocurrency, increased by 34,900% in 2017. In 2018, the value plummeted by 77%, but the price remained largely constant in 2019 and 2020. The output of the company increased in 2021, with a 226 percent improvement from January to March. It has a market capitalization of $12.4 billion as of April 6, 2021.
For traders seeking to diversify their portfolio away from bitcoin, Stellar may be an intriguing option.

What is the Process of Stellar?

The basic operation of Stellar is close to that of other decentralised payment systems. It operates a network of shared servers with a distributed ledger that is modified every 2 to 5 seconds for all nodes. The consensus protocol is the most notable difference between Stellar and bitcoin.
To accept transfers, Stellar's consensus protocol does not depend on the entire miner network. Instead, it employs the Federated Byzantine Agreement (FBA) algorithm, which allows transactions to be processed more quickly. This is how it approves and validates transactions using quorum slices.
Each node in the Stellar network selects a different group of "trustworthy" nodes. A transaction is called accepted until it has been accepted by all nodes in this package. Stellar's network is said to handle as much as 1,000 network operations a second thanks to the streamlined process.

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How Can Stellar Make Cross-Border Transfers Go Faster?

The new cross-border migration procedure is cumbersome. It allows domestic banks to keep local currency accounts in international jurisdictions. In the original world, their corresponding banks must maintain a comparable account.
For cross-border transactions involving fiat currencies, the Nostro-Vostro method, as it is called, is a lengthy one involving conversion and account reconciliation. Stellar's blockchain may reduce or remove delays and confusion while allowing for simultaneous validation.
SCP is used by the Stellar Network to achieve agreement in its platform; but, unlike other standard consensus protocols, SCP does not specify a framework of node rewards or a system for coin emission (useful in the case of cryptocurrencies and public blockchains). As a result, the emission of Lumens (XLM) by the Stellar
Network is unaffected by its consensus protocol.

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Quorums, slices and intersections

• Quorums and quorum slices are at the heart of the SCP. The following are the meanings of certain terms, as mentioned in the SCP Whitepaper:
• A quorum is a group of nodes large enough to achieve a consensus.
• A quorum slice is a group of nodes large enough to persuade another node that a statement is true. Often known as'slices'

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Nodes in the Stellar Network choose which other nodes they trust for knowledge on their own. As a result, the quorum slice of n is described by the collection of nodes chosen as "trusted" by node n and node n itself. If n has both l and m in its slice and they both accept a piece of material, n will accept it as well. If l and m each have two other nodes in their slices, the quorum must be formed by these nodes as well. As a result, a quorum is a group of nodes of at least one slice from each of its members.

There are some limitations.

SCP has the following limitations, according to David Mazières, its creator:
It doesn't have a system in place to create digital coins.
It doesn't have a system in place to encourage nodes to behave well.
It doesn't tell nodes who they can trust, which means nodes can choose bad quorum slices (despite having incentives to avoid doing so) and potentially harm consensus.

Conclusion:

The Stellar Consensus Protocol (SCP) is a framework for global agreement. SCP is the first provably secure consensus system with decentralised authority, low latency, scale-able confidence, and asymptotic protection all at the same time. When a node determines that an upgrade is secure to implement, it externalises, or publishes, the agreed-upon declaration to their ledger replica. When all nodes change their ledgers and externalise the same value, they have achieved consensus.