DEV Community: Shreya Shenoy

Consensus Mechanisms: How Blockchains Reach Agreement

Shreya Shenoy — Thu, 15 Jun 2023 00:02:59 +0000

In a decentralized system, maintaining trust is essential and consensus mechanisms play a crucial role in ensuring the secure addition of blocks. In this post, we will explore two of the most widely used consensus mechanisms: Proof-of-Work (PoW) and Proof-of-Stake (PoS).

It's important to note that numerous other mechanisms exist, each with its unique characteristics and benefits. And if you're curious to explore additional consensus mechanisms, make sure to check out the linked resources at the end of this article!

Consensus model: Proof-of-Work

In Proof-of-Work (PoW), miners (participating nodes) compete to solve a cryptographic puzzle. The first miner to solve the puzzle is rewarded with cryptocurrency and is given the right to add the block to the chain. Bitcoin operates on this consensus model.

The cryptographic puzzle is a hash function that takes as input the block header and a nonce. Miners compete to solve the puzzle by repeatedly changing the nonce until the hash meets a certain criteria. The hash function is designed to be very difficult to compute, but very easy to verify. To solve this, miners use specialized hardware to perform billions of calculations per second.

Once a miner finds a nonce that generates a hash that satisfies the difficulty requirements, they broadcast the solution to the network. The other miners then verify the solution and add the block to the blockchain. The miner who found the solution is rewarded with newly minted cryptocurrency.

This process ensures that blocks are added to the chain in a secure and transparent way. It also prevents anyone from tampering with the blockchain, as any changes would be immediately apparent to the network.

It is also a way to prevent double-spending attacks. A double-spending attack is an attempt to spend the same bitcoin twice.

Drawbacks to Proof-of-Work

The computations needed to add a block in the proof-of-work consensus mechanism require massive amounts of computer power, which translates to a significant amount of energy consumption. This has become an environmental concern as the popularity of cryptocurrencies has grown.

Proof-of-work is also slower and less scalable than other consensus mechanisms.

Proof-of-Stake (PoS) is a consensus mechanism that has grown in popularity. Ethereum officially switched to PoS in 2022 as a more secure and energy-efficient way to validate transactions and add new blocks to the blockchain.

To illustrate the difference, Bitcoin can only process around 7 transactions per second, while Ethereum can process around 30 transactions per second.

Consensus Model: Proof-of-Stake

In PoS, staking replaces mining competitions. Participants who wish to engage in currency forging need to put up a certain amount of tokens (stake). One node out of the participating nodes is randomly selected to validate the block being added.

The random selection of nodes to validate blocks is not truly random. There are a few factors that influence the probability of being selected, such as the amount of cryptocurrency staked by the node. For example, someone with more money at stake has higher chances of being selected to validate the node. Additionally, different cryptocurrencies use different selection techniques, such as randomized block selection and coin age selection.

How does PoS maintain security?

Due to their own currency being at stake in this mechanism, nodes are incentivized to validate blocks honestly because they are penalized if they are caught cheating. If a node validates a block that is invalid, they will lose a portion of their stake. This helps to ensure that the network is secure and that nodes are not able to manipulate the blockchain.

Validators who validate blocks correctly are rewarded with transaction fees.

This way PoS is more energy-efficient, as it does not require miners to use specialized hardware to solve complex mathematical puzzles. It is also more scalable and can handle a larger number of transactions.

TLDR? Here's a short video outlining the difference between the two consensus mechanisms and also describing some others out there:

Also, check out these links to learn about additional consensus mechanisms:

12-min Video Explaining 7 Different Mechanisms
Solana's use of Proof-of-History
Beginner's Article: Consensus Mechanisms in Blockchain

Overall, blockchain is promising technology with the potential to revolutionize the internet as we know. It is still in its early stages of development, but it is already being used by a wide range of businesses and organizations.

Here's an overview of the concepts covered in this series:

Web3 is a new decentralized internet that is built on blockchain technology, and it is still in its early stages of development. However, there are already a lot of cool developments happening in web3, such as decentralized finance (DeFi), non-fungible tokens (NFTs), and decentralized autonomous organizations (DAOs).

If you are interested in learning more about blockchain technology and web3, follow me on dev.to and Twitter. I would be happy to answer any questions you have.

Blockchain Basics: Deconstructing the Tech Behind Cryptocurrencies

Shreya Shenoy — Mon, 05 Jun 2023 17:22:49 +0000

In January 2009, amidst the worst recession the world had seen at the time, Satoshi Nakamoto, a pseudonymous creator, released an application of a previously theoretical concept: a new currency on the internet that didn't rely on any banks to keep track of accounts.

This currency was decentralized, meaning it was not controlled by any single entity. Instead, it was maintained by a network of computers all over the world. This made it more secure and transparent than traditional currencies.

The technology that made this possible was called blockchain. It is the foundation of cryptocurrencies like Bitcoin and Ether.

In this article, I will explain how blockchain works and how it can be used to create a more secure and transparent financial system.

How is cryptocurrency different?

In traditional finance, transactions are verified and recorded by a central authority, such as a bank. This means that the central authority has control over the money supply and can track all transactions.

Cryptocurrency, on the other hand, is a decentralized digital currency that uses blockchain to verify and record transactions. Blockchain is a distributed ledger that is maintained by a network of computers all over the world. This means that there is no central authority and no single point of failure.

Imagine you're at a social gathering with a group of people, and one person confidently announces that they have a million dollars in their bank account. In a traditional financial system, you would have no way to independently confirm this claim unless you had direct access to their bank records. You would essentially have to take their word for it.

Now, let's imagine a different scenario where both of you are part of a cryptocurrency network. In this decentralized system, you can actually verify the validity of their claim. This is because cryptocurrencies operate on blockchain, which publicly and securely, records all transactions.

So, if this person wants to send you 100 coins as a demonstration, you and others on the network can examine the blockchain's public ledger to validate whether they genuinely have the funds they claim to be sending. This transparency allows for verification by consensus, reducing the need for blind trust.

This is just one of the ways in which cryptocurrency differs from traditional finance. The technology offers a level of transparency and accountability that empowers individuals to verify transactions without relying solely on trust or centralized authorities.

How does blockchain work? Let's take a look at some of the key components of a blockchain network.

The Block

From a data structure perspective, a block is an abstract container that holds an encrypted collection of network transactions along with other data.

Some key components of each block:

Hash of the previous block: This is a unique identifier for the previous block in the chain. It ensures a secure cryptographic link between blocks.
Merkle root: This is a binary hash tree that produces a digital fingerprint of the entire set of transactions in the block. This is used to quickly verify the contents of the block without having to re-hash all the transactions.
Nonce (short for number only used once): This is a random number that is used to generate the block's hash. The nonce is changed until the hash meets a certain criteria, making it very hard to tamper with.
Timestamp: This ensures the blocks are ordered chronologically.
Transaction data: This is the data that is being stored in the block. This can include information such as the sender, receiver, amount, and time of the transaction.

Everyone that is on the blockchain network can access the blocks and view the transactions that have taken place. This transparency is one of the key benefits of using blockchain technology.

If you're interested to learn more about blocks here are some cool links:

How do you get on a blockchain network? This brings us to the next component.

The Node

A node is a computer or server that is connected to a blockchain network. Nodes are responsible for storing the blockchain data, validating transactions, and relaying information to other nodes.

To become a node in a crypto network, you need to:

Install the blockchain software of your interest on your computer. The software will allow you to connect to the network and participate in its operations.
Sync your node with the blockchain network. This will ensure that your node has the latest blockchain data.
Start participating in the network by validating transactions and relaying information to other nodes. You can do this by running the blockchain software and connecting to the network.

Once you have the node running, you will be able to view the blockchain data, validate transactions, and earn rewards for validating transactions.

Here are some links to get started with popular blockchain software:

Can any node add to the Bitcoin blockchain? How are blocks added? How exactly does the blockchain enable transparency and security among participants? This brings us to the next key component of the blockchain.

The Chain

The blockchain is a back-linked list of chronologically ordered blocks. Each block is linked to the previous block through a cryptographic hash, enabling the verification of transactions.

How are blocks added to this chain?

To maintain the security and transparency, blocks are added through a consensus mechanism. This means that a majority of participants in the network must agree that a block is valid before it can be added to the chain.

There are many different consensus mechanisms, but the two most common ones are Proof-of-Work and Proof-of-Stake.

For more on consensus mechanisms, check out the second part in this series, "Consensus Mechanisms: How Blockchains Reach Agreements"

Overall, blockchain is promising technology with the potential to revolutionize the financial system. It is still in its early stages of development, but it is already being used by a wide range of businesses and organizations.

Here's an overview of the concepts covered in this series:

If you are interested in learning more about blockchain technology and web3, follow me on dev.to and Twitter. I would be happy to answer any questions you have.