zkBridge uses zkSNARKs to enable a prover to efficiently convince the receiver chain that a certain state transition happened on the sender chain. zkBridge consists of a block header relay network and an updater contract.
The block header relay network retrieves the block headers from the sender chain, generates proofs of the validity of the block headers, and sends the headers along with the proofs to the updater contract (set up on the receiver chain).
The updater contract maintains a light-client state. It automatically adds block headers of the sender chain once the associated proofs are verified, and updates the current main chain of the sender chain.