Harmony today announced Horizon, a trustworthy validator-powered bridge between Ethereum and Harmony.
Harmony introduced SWOOP, a decentralized exchange (DEX) for transferring assets bridged from Ethereum, just a few weeks after Horizon. In fact, Horizon and SWOOP collaborated to show our users Harmony’s low-cost, high-speed, and frictionless asset exchange experience (with TVL 200K USD).
Harmony is a sharded layer-1 blockchain based on Proof of Stake and Byzantine consensus, with 2-second block completion and a system of 1000 decentralized nodes. Harmony’s cross-chain architecture builds around a unique gas-efficient light client technology. The light client’s gas performance is critical, particularly when implemented cross-chain, such as Ethereum.
Harmony generates blocks at a blistering rate of 2 seconds per block, making an SPV-style light client unsuitable for cross-chain use. To be practical for cross-chain usage, the Harmony lite client incorporates numerous advances.
First, there’s epoch-based synchronization. A light client is a software that downloads blockchain data and validates it. SPV is a straightforward light client that receives and verifies each block header. A Proof-of-Stake blockchain’s light client simply has to check the credentials of the verifiers who signed the blocks. Because the verifier set does not evolve over the course of an epoch (about one day), the light client only has to download one block header per epoch. This alone minimizes the light client’s complex nature by a significant amount (1/32768 blocks).
BLS Signature
The BLS signature aggregation comes next. To submit a block to the blockchain, Harmony’s consensus process demands a quorum of 2/3 or more verifiers to sign it. Also, BLS signatures use by Harmony verifiers to sign blocks. Rather than storing each of these signatures independently on-chain, a single accumulated signature is stored—a wonderful feature of BLS that enables this. This decreases the amount of work that the light client has to do in order to verify the block.
Finally, similar to FlyClient, checkpointing center on the Merkle Mountain Range (MMR). The light client is not gas-efficient for cross-chain applications just because it uses epoch-based synchronization and BLS signature aggregation. The BLS signature validation uses elliptic curve pairing, which uses 400K of gas per confirmation on Ethereum. Indeed, The Harmony Light client uses a novel MMR-based checkpointing strategy to avoid costly pairing-based confirmation.
Each epoch’s blocks link together in the form of an MMR, with the MMR root contained in each and every block header. The light client can confirm the block without having to do costly BLS signature verification by checking the MMR commitment.
Harmony, a scalable and open blockchain for decentralized applications, is now available to developers. State sharding with instant finality supports by the Harmony Mainnet. Its staking method promotes delegation and slashing while reducing centralization.
