April 24, 2020

How can Stellar be so fast?

If you’ve used our XLMwallet, you know that Stellar is exceptionally fast compared to Bitcoin and Ethereum. How is it possible? They are all blockchains, after all. Does the high speed mean that Stellar is centralized? Not at all — here’s why.

With XLMwallet you can send and receive lumens (XLM) in under 5 seconds. For comparison: with Bitcoin, one confirmation takes 10 minutes (1 block time), and many exchanges and dApps require more than 3 confirmations. So your recipient will need to wait for half an hour or more to get their money.

5 seconds vs 10 minutes — it’s a 120x difference! How can one blockchain network be 120 times faster than another?

Some people who are not familiar with Stellar think that it must be centralized to be so efficient. But the truth is very different!

SCP vs PoW

The key reason why Stellar has such a huge processing speed is that it uses a completely different consensus protocol.

As you probably know, Bitcoin employs Proof-of-Work, where miners have to waste lots of resources trying to find a solution (hash) for each block. Network members together agree that the found hash is correct, and whoever found it first gets a reward. This agreement is known as consensus.

PoW a good system in the sense that it’s difficult to attack. A thief or hacker would need to spend a gigantic sum of money to force the network to agree on something that is not true. But PoW is also hugely wasteful. Maybe you’ve heard that Bitcoin mining consumes as much energy as a small country — it’s true!

The Byzantine problem

Instead of PoW, Stellar uses something called Federated Byzantine Agreement (FBA). This consensus model answers the same question: how can we make the nodes in the network work for the common good? How can we prevent evil agents (nodes) from colluding with each other and deceiving others?

The word Byzantine refers to the so-called Byzantine Generals Problem. The generals are sieging an enemy city, each with his own division. They have to decide if they want to attack, and the only way to communicate is to send a messenger. Some of the generals are actually enemy spies, so they send conflicting messages. Other messages can get lost. The problem is, how do we find out what the real generals think?

Stellar solution

Stellar’s Federated Byzantine Agreement can solve the problem. This model was created in 2015 by a professor from Stanford University. It’s too complicated to describe it in detail here, but here are some facts:

- All the nodes are divided into quorums (groups). Within each quorum, each node trusts some other nodes, and these ‘circles of trust’ are called slices.

- Nodes reach an agreement within each quorum.

- Different quorums intersect, and that ensures general agreement across the network.

- Even if many nodes turn ‘evil’ or get turned off, the system still reaches an agreement.

The bottom line is that there’s a very complex system of interlocking ‘agreement groups’, voting and ballots. Still, it’s many times faster than PoW — and yet very hard to break or hack into. You can read more here.

Even if you don’t know anything about consensus protocols, don’t worry. You can still use XLMwallet and enjoy all of its advantages: fast crypto transfers, user-friendly web interface, support for all Stellar assets (lumens and tokens), transfers by email, account merging, and so on.

By the way, now is still a good time to buy some more XLM. It’s been growing steadily and gained more than 20% in just one week. But there’s still a huge potential for growth after the Bitcoin halving on May 18.

So better make up your mind now — you can buy XLM on any major exchange. To protect your investment, withdraw the lumens from the exchange and store them safely in XLMwallet — the fastest, lightest web wallet for Stellar.

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