Secure Proof of Stake (SPoS): Revolutionary Consensus

In this blog, you are going to learn the deep details about the Revolutionary Consensus algorithm called Secure Proof of Stake (SPoS).

Secure Proof of Stake (SPoS) consensus, Elrond has proposed a novel approach to consensus called Secure Proof of Stake.

It takes out PoW computational waste and consolidates qualification through stake and rating with arbitrary validator choice and an ideal aspect for the consensus group.

SPoS is based on the observation that the underlying mechanism behind Proof-of-Stake (PoS) does not require the creation of new blocks from scratch, but rather extends validator inclusion by picking randomly from the set of all potential candidates at each step in the process.

Related Article: Chain Based Proof of Stake: Comprehensive Guide

What is SPoS?

Elrond Network has introduced a solution called Secure Proof of Stake (SPoS), SPoS does not require an excessive amount of computational waste in order to reach a consensus.

Secure Proof of Stake combines eligibility through stake and rating with random validator selection and an optimal dimension for a consensus group.

This is achieved by having all network participants provide validation during a two-phase commit protocol, while they also obtain voting rights on future protocol changes.

The Randomized Delegation approach ensures that every validator can be removed from the consensus group if certain conditions are met.

Our main contribution is a distributed computation scheme where instead of exchanging key information or hash values among nodes.

We can complete operations such as integer modulus and discrete logarithm computations via secure function evaluation over encrypted data.

Further, our cryptographic primitives incorporate (delegatable) threshold signatures which removes one round of decryption in delegated computation.

Related Article: What is Delegated Proof of Stake (DPoS)?

What is SPoS Consensus Algorithm?

SPoS is a consensus algorithm that has been proposed by Elrond, This protocol combines eligibility through stake and rating.

Secure Proof of Stake generates trust via honesty and by ensuring convergence on order.

Secure Proof of Stake avoids computation waste from PoW protocols as well as human-generated noise from PoS-based systems.

Further, it increases privacy and decreases the risk of blockchain forks over existing consensus mechanisms.

How Does SPoS Work?

The network requires both a sufficient number of validators and that those validators are highly trustworthy.

In order to ensure these two properties are met, Elrond leverages proof-of-stake which inherently provides a form of financial incentive for individuals or groups which act honestly, creating an intrinsic barrier against potential malicious actors. This approach is called Secure Proof-of-Stake.

In SPoS, each node carries out voting on new blocks proportional to its stake. Votes are weighted by the stake to avoid voting attacks whereby an attacker with no stake could accumulate votes from others who trust them or pay the cost of delegating their vote.

These trusted voters are selected using Randomized Delegation, in combination with a rating system proposed by Zhong et al.

Specifically, when a block needs to be voted upon, we first lookup all nodes whose stake exceeds some minimum threshold s_min and randomly select n_v such nodes.

Then we sort all m online nodes in descending order of rating R(n) then randomly select r_v nodes from that group.

What is Elrond?

Elrond Network is a next-generation Blockchain, providing a highly scalable, secure, and interoperable payments and smart contracts platform.

Building on lessons learned from Bitcoin, Elrond can support over 1000 transactions per second with unparalleled security.

It will act as an ideal public blockchain for enterprise solutions that require private data. Existing cryptocurrencies have no answer to scalability and privacy problems in their current form; Elrond aims to fill that gap.

In order to be truly fair, however, we need to take a close look at consensus algorithms.

The basic definition of consensus means a general agreement between two or more parties about something.

Blockchains are unique because they use consensus algorithms across multiple machines that do not know each other well at all; as such there is always risk involved.

What is the Issue With Mining?

In order for a cryptocurrency protocol to function, there must be some way to agree on who should create and record new blocks.

Currently, blockchain protocols primarily rely on mining as a way of coming to a consensus on what block is valid and what block isn’t.

Mining consumes large amounts of computational power and generates large amounts of heat and wastes resources in electricity consumption.

Besides that, miners are only required by protocol rules in public chains like Bitcoin or Ethereum.

However, if one wants a blockchain where not just anyone can participate as a miner, how does one come to a consensus about adding blocks? This is where Secure Proof-of-Stake comes into play.

Verification of SPoS Mechanism

Elrond defines a new mechanism to determine whether a given stakeholder is eligible to participate in consensus.

Eligible stakeholders can either be active or passive, with an active stakeholder being one who stakes at least 1% of all network tokens and has submitted at least 0.5 rating reports within the last 6 months.

Passive stakeholders are those who have not met these criteria, but their total held stake represents more than 2x their minimum required staking amount.

Each day’s node-set will include randomly selected passive stakeholders until they collectively represent no less than 10% of that day’s block producer set.

A random subset will then be chosen from among both active and passive nodes with Y-coordinate below X algorithm where X = number of active nodes and Y = number of passive/inactive nodes that remain after rounding down.

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Future of Cryptocurrency with SPoS

Elrond’s Secure Proof of Stake protocol solves major issues in PoW and PoS.

In any blockchain, it is important to maintain a healthy ecosystem, with high transaction processing rates and low block generation times.

Additionally, we want to ensure fair distribution so that more people are able to participate meaningfully, Secure Proof-of-Stake achieves both these objectives effectively.

SPoS also has strong resistance against a number of attacks like selfish mining and eclipse attacks which affect traditional cryptocurrencies like Bitcoin and Ethereum.

And best of all, SPoS uses 80% less energy than Bitcoin or Ethereum! With SPoS, we could change the future of cryptocurrency for everyone.

Related Article: What is Tokenomics? – Guide on Crypto & Tokens

Advantages of Secure Proof of Stake (SPoS)

Secure Proof of Stake (SPoS) uses a deterministic approach based on the stake and rating weighting, thus removing computational waste and non-determinism from achieving finality.

The percentage allocation required for validator selection adds further value by

i) adding extra entropy by requiring 100% participation in each block;

ii) allocating consensus group size based on a dimension;

iii) limiting stateless validators to 1 dimension worth of stake in each block.

SPoS opens up an entirely new paradigm with huge positive repercussions which we’ll explore in later posts, but first, let’s examine SPoS through a proof of concept.

Disadvantages Secure Proof of Stake (SPoS)

There are some disadvantages with Secure Proof of Stake (SPoS), one being its increased centralization.

The nodes in PoS blockchains that secure and validate transactions are not chosen randomly, unlike with other consensus mechanisms like Delegated Proof-of-Stake.

Instead, they are selected based on a combination of stake and rating – i.e., how much they have invested in their blockchain’s native token and how much they contribute to validating transactions on that blockchain.


This piece provides an in-depth dive into secure proof of stake. Although SPoS is a little complex, it’s an ingenious solution that offers a number of advantages over traditional consensus algorithms.

By providing security without PoW computational waste, SPoS may be one step closer to solving blockchain scalability and environmental concerns.

Regardless of your background, after reading this guide you should have a better understanding of secure proof of stake technology.