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Sigma Chains#

Sigma Chains represent a groundbreaking innovation designed to revitalize Proof of Work (PoW) and solidify Ergo's position at the centre as a hub. By introducing programmability, cross-chain compatibility, and economic sustainability, Sigma Chains unlock a multitude of possibilities for Ergo and its ecosystem.

What are Sigma Chains?#

Sigma Chains are a series of blockchains that share the same contractual base layer, while allowing for different chain-specific features and customization. They represent a universe of programmable money, offering a compelling alternative to the Ethereum Virtual Machine (EVM) for PoW and UTXO-based blockchains.

The Sigma Chain standard has already proven its success in the PoW and UTXO setting, with Ergo currently ranking as the #1 PoW blockchain in terms of Total Value Locked (TVL) relative to its market capitalization. Beyond serving as a powerful contractual base layer, Sigma Chains are designed to operate as a cross-chain standard, enabling seamless interoperability and trust-minimized communication between different blockchains through advanced cryptographic techniques such as zero-knowledge proofs and threshold signatures.

Ergo at the Center of Sigma Chains#

Sigma Chains are built upon the robust foundation of Ergo, leveraging its advanced features and technologies to create a thriving network of interconnected blockchains. With different pegging mechanisms, Sigma Chains offer more flexibility compared to other blockchain ecosystems like Cosmos and Polkadot. This flexibility allows for a wide range of cross-chain interactions and enables the creation of a diverse ecosystem of interconnected chains.

Sigma Chains also place a strong emphasis on cross-chain security. While the security assumptions behind solutions like Cosmos IBC, Polkadot, and BIP-301 may be unclear, Sigma Chains prioritize a robust and well-defined security model. By focusing on cross-chain security, Sigma Chains ensure that the interconnected network of blockchains remains resilient and resistant to attacks, providing a secure environment for users and developers alike.

Moreover, the growth of Sigma Chains will accelerate development and increase Ergo's mindshare in the blockchain space. As more developers and projects recognize the potential of Sigma Chains and the benefits of building on top of Ergo, the ecosystem will flourish. This increased mindshare will attract more talent, resources, and innovation to the Ergo ecosystem, cementing its position as a leading blockchain platform.

Key Features of Sigma Chains#

  • Programmability: Sigma Chains support complex smart contracts and DApps, enabling a wide range of applications from DeFi to digital identities. They utilize the ErgoScript language, which is flexible, Turing-complete, and prioritizes security.

  • Cross-Chain Compatibility: Sigma Chains facilitate seamless interactions between Ergo and other blockchain networks, enhancing liquidity and interoperability within the blockchain ecosystem. They enable trustless value pegging between chains.

  • Sustainability: Sigma Chains introduce storage rent and demurrage to ensure long-term economic sustainability. Storage fees serve as additional rewards for miners while stimulating coin circulation.

  • Security and Decentralization: Maintaining the robust security model of PoW, Sigma Chains benefit from decentralized consensus mechanisms, ensuring network integrity and resistance to censorship. Sigma protocols enable true peer-to-peer privacy.

Revitalizing Proof of Work with Merged Mining#

Sigma Chains introduce an innovative approach to revitalizing PoW through merged mining. Being algorithm agnostic, Sigma Chains can serve as an attractive alternative for unprofitable miners across various hardware classes (ASIC, GPU, CPU), empowering them to contribute to the security and growth of the entire Ergo ecosystem. Merged mining on Sigma Chains allows Ergo miners to be paid in various tokens while still requiring ERG for transactions on the Ergo network, creating a sustainable economic model that benefits both miners and the overall ecosystem.

Empowering Portable Projects and DApps#

Sigma Chains enable the creation of portable projects and DApps that can seamlessly interact across multiple blockchains. Sigma Chains come with built-in DeFi frameworks and dApps from day one, allowing projects to bootstrap faster and reward existing Ergo holders. Portable projects gain access to other on-chain markets, expanding their reach and potential for growth. Sigma Chains utilize the Sigma protocol suite, which provides a robust and modular framework for building complex financial applications, offering a wide range of DeFi primitives that can be easily integrated and adapted across different chains.

Architecture of Sigma Chains#

Sigma Chains utilize a layered architecture that allows for the development of complex applications while maintaining the security and integrity of the blockchain. Sigma protocols enable the construction of advanced cryptographic operations, providing the foundation for secure and versatile smart contracts. Sigma Chains use the extended UTXO model, enabling superior privacy, scalability, interoperability, and cost predictability compared to account-based models. They support Non-Interactive Proofs of Proof-of-Work (NIPoPoWs), allowing users to run contracts on common devices without centralized intermediaries. Many network parameters are adjustable through decentralized voting among miners, allowing them to steer the long-term economic stability of the network.

Smart Contract Emissions with No Premine#

Sigma Chains introduce a novel approach to token distribution through smart contract-based emissions. This mechanism allows for the creation of multiple treasuries built into the emission curve, rewarding investors, developers, and the community without the need for premining. Protocol-based emissions will be structured in new Sigma Chains to reward early investors, providing them with a stake not just in a single ecosystem but in the entire Sigma standard. Smart contract emissions can also be used to build treasuries for development, community initiatives, and marketing efforts, ensuring the long-term sustainability and growth of the ecosystem.

Sidechain Constructions#

Sigma Chains offer various efficient sidechain constructions that cater to different use cases and mining preferences:

  • Merged-Mined Sidechains: Merged-mined sidechains allow Ergo miners to simultaneously mine both the Ergo mainchain and the sidechains, providing efficient and trustless cross-chain interoperability. Smart contracts on the Ergo mainchain can read sidechain data, enabling seamless and secure pegging between the mainchain and sidechains. The pegging security is equivalent to the security of the sidechain itself, benefiting from the combined mining power of both the mainchain and the sidechain miners.

  • Double Merged-Mined Sidechains: Double merged-mined sidechains offer an innovative approach to bridging Ergo with other PoW blockchains, such as Bitcoin, while minimizing trust requirements. In this setup, a Sigma Chain acts as a Bitcoin sidechain, including commitments to both the Bitcoin and the sidechain UTXO sets written on the blockchain. This enables the execution of rich applications directly on the Bitcoin blockchain, with Bitcoin transactions submitted to the Bitcoin blockchain and auxiliary data submitted on the sidechain.

  • Dedicated Mining Algorithms: Sigma Chains support dedicated mining algorithms, allowing for the creation of sidechains tailored to specific hardware types. These sidechains feature a dedicated PoW consensus mechanism alongside the Sigma contractual layer and additional chain-specific features. With the inclusion of Autokoyos2 verification and built-in support for Ergo headers, trustless replay protection can be implemented through on-chain contracts, enabling the creation of SPV clients for sidechains. Sidechains with dedicated mining algorithms can utilize relay contracts to incentivize mainchain miners for submitting proper sidechain data on the mainchain, providing a clearer and more secure incentive mechanism compared to the BIP-301 proposal.


Sigma Chains represent a significant leap forward for Ergo and the broader blockchain ecosystem. Sigma Chains create new opportunities for miners, developers, and users alike. With increased demand for ERG, expanded collateral opportunities, and a thriving ecosystem of portable projects, Ergo is poised to lead the charge in the era of programmable PoW.

As Sigma Chains gain momentum, Ergo will solidify its position as a key player in the blockchain space, driving innovation and adoption across all hardware classes. In time we can invest other options. Zk- trustless Bulletproof based relays on the mainchain.