Namada-Eth bridge for private and secure transactions

I've been hearing about so many privacy breaches lately, I thought it was about time I did some research into various privacy protocols that interact with Ethereum. That's when I came across the Namada protocol and their native light client-based bridge to Ethereum. Thought I’d share how the bridge works and why using Namada could be a good and secure solution to ensuring your privacy.

Namada is a privacy-preserving L1 designed to shield your assets in a unified privacy set without the need for a fiddly privacy integration set-up: you just transfer your assets into a single multi-asset shielded pool and then interact with other chains - in this case Eth.

What’s interesting about Namada’s-Eth bridge (instead of being a standalone protocol) is that it directly integrates into the Namada protocol which means that the liveness and security of the bridge is tied to the liveness and security of Namada. When transferring assets to Namada, Namada validators act as relayers but when transferring assets to Eth, other relayers are involved but are not responsible for any validation or bridge security.

To get an overall idea of the design itself, Namada validators will run Eth nodes and monitor events by the bridge’s smart contracts deployed on Eth. Events from the smart contracts are triggered by token movement across the bridge and Namada validators wait until the triggering transaction has finished to then share with other validators that they have seen a certain event emitted from Eth.

If you want to transfer assets to Namada the chain acts as an oracle for relevant Ethereum contracts and so once you submit the transaction, an event will be seen and voted on by Namada validators. The issuing of assets will occur automatically once it has the backing of a quorum. Also, the payment of gas on the Eth side of the bridge is enough to prevent any DdoS attacks.

Now if you want to transfer assets back to Eth, there are a few more steps involved. Eth validators don’t run full Namada nodes so transactions that initiate a transfer to Eth need to be relayed through a smart contract. To reduce the overhead cost of sending individual transactions, Namada keeps an ‘Eth bridge pool’ which contains requests to transfer assets to Eth and sends them in a batch transaction. When a user adds a transfer request to the pool, they can choose to pay in NAM or another asset as a fee. Anyone may choose to relay a subset of transfer requests which are organized as a Merkle tree and whose root is then signed by Namada’s validators. By using Merkle trees (as I understand), any subset of the bridge pool may be relayed in any order and thus prevents attacks when multiple small transactions are sent over the bridge to slow it down.

Here’s a full blog with all the details about the bridge if you want to know more: https://blog.namada.net/the-namada-ethereum-bridge/

Namada is launching Mainnet very soon. I’m staying tuned!