Building Bridges Between Blockchains With t-ECDSA Keeps

Privacy makes interoperability possible

Imagine a future where blockchain-based solutions can work together, where the benefits of one chain are extended to another. A world where blockchains are interconnected is one where the technology flourishes with greater engagement, adoption, and utility.

At Keep, one of the things we’re building is cross-chain bridges for interoperability between public chains. T-ECDSA keeps support decentralized signing across chains, creating solutions that allow for cross-chain communication.

The future of interoperability and cross-chain bridges

Today, blockchains exist in silos. They’re developed within their own ecosystems that don’t talk to one another. The development of blockchain technology has largely been a competitive race; focusing on who will build the next Bitcoin or who will solve the big problem of the moment. Continuing down this path will leave the industry fractured between capabilities, resources, and understandings for how things should work. It will sideline many people, limiting adoption and engagement.

The inclusive path forward is one of interoperability where chains benefit from one another and users don’t have to choose between capabilities or features. But in order for chains to be interoperable, they require a mechanism for cross-chain communication.

The Keep connection

The Keep Network is a privacy layer for public chains that supports deep interactivity with private data and interoperability across chains. It does this with keeps, smart contracts that allow other smart contracts to interact with private data in a secure way.

Keep supports cross-chain communication with threshold elliptic curve digital signature algorithm (t-ECDSA) keeps. Built on ECDSA, an algorithm supported by many of the top blockchains, t-ECDSA keeps facilitate decentralized group signing with multi-party threshold signatures even if group signatures are not available on the host chain.

t-ECDSA keeps

Implemented with secure multi-party computation (sMPC), t-ECDSA keeps make it possible for contracts to communicate cross-chain by signing transactions between chains with a number of geographically distributed threshold signers.

T-ECDSA keeps secure the transactions with multiple individual key shares, held independently by multiple signers. Decentralized signing is performed with sMPC for computation on private key shares without revealing them. Responsibility for signatures is divided, requiring a threshold number of participants to create a signature using their key shares.

Homomorphic encryption allows secret sharing within the threshold multi-signer system. This facilitates public key cryptography while ensuring that each key is kept private. Read more about homomorphic encryption in my earlier blog post entitled, “Keeping Secrets in Public Places with Homomorphic Encryption”.

How t-ECDSA keeps work

An Ethereum smart contract asks our network to open a new t-ECDSA keep. This keep is backed by a group of randomly selected signers from our sMPC cluster. Those signers use t-ECDSA to generate the key and provide a signature. The signers can sign anything, including blockchain transactions. The Ethereum smart contract can ask the keep to sign a transaction on any blockchain-based on ECDSA, Bitcoin is just one of them.

This mechanism is trustless because signers are independent; they’re people and organizations running sMPC cluster nodes. Joining a cluster is done via the KEEP work token. The signed transaction can be anything. For example, it can be an order to send funds somewhere — we can issue BTC transfer from the ETH chain. As a result, BTC is controlled from the ETH chain, which is just one of the possibilities for a t-ECDSA bridge.

We can build entire applications on top of that and add various rules to accommodate needs. As such, the Keep network is like a bridge, connecting the interoperability gap between those two chains.

Building on Ethereum, and beyond

Keeps can sign transactions on any chain developed with ECDSA, meaning that we aren’t limited to transactions just between ETH-BTC. Today, 12 of the top 20 coins on CoinMarketCap use ECDSA, including BTC, LTC, XRP, BCH, BNB, DASH, and more. An “ETH-ETH” bridge could be used to sign a 0x order, normally only possible via a live user within a dApp.

Further, the sMPC cluster we are working on can be integrated with any chain. So, rather than focusing on the particular features of two specific chains, we’re able to focus on connecting supporting chains.

Interoperability happens when blockchains can talk to one another. We’re building bridges for cross-chain communication with t-ECDSA, a mechanism to break down barriers and connect public blockchains.

Learn more about homomorphic encryption in this May 24th blog post and see this blog post from December 21st to learn more about t-ECDSA.

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