How the bridge works: Ethereum ⇄ PulseChain, animated

Ethereum and PulseChain are two separate ledgers: neither can read the other, and a token cannot simply walk across. The official bridge solves that with a contract on each chain and a group of validators who pass signed messages between them. Below it is drawn as a machine — press Play, then switch the direction and play the way back. Toggle Show admin keys to see where the trust sits.

Why does a bridge need two contracts?

Because each chain only trusts what happens on itself. The bridge therefore keeps a token contract (the mediator) on both chains and a message box (the Arbitrary Message Bridge, AMB) next to each. Tokens never leave Ethereum: they are locked there, and a matching amount is minted on PulseChain. On the way back the PulseChain tokens are burned and the locked originals are released. This is the OmniBridge design originally written by POA Network and Gnosis, deployed for PulseChain with its own validators and keys (the bridge).

What happens when I bridge to PulseChain?

1. You send the token to the bridge contract on Ethereum. It locks the token and posts a message.
2. The validators wait for 65 Ethereum blocks — about 13 minutes.
3. Each validator confirms the message on PulseChain; once 5 different validators have confirmed, it is carried out.
4. The PulseChain contract mints the same amount, named “… from Ethereum”, to your address. On 2026-10-17 this direction charged no bridge fee; you pay Ethereum gas.

What happens on the way back?

1. You send the bridged token to the bridge contract on PulseChain. It takes the fee — 0.30 % on 2026-10-17 — and burns the rest.
2. After 65 PulseChain blocks (about 11 minutes), the validators sign the message on PulseChain until 5 signatures are collected.
3. You claim: you send the message with the signatures to Ethereum and pay the gas. Nothing is released before this step.
4. The Ethereum contract checks that at least 5 different current validators signed, then releases the tokens from the vault.

Who are the validators, and why 5 of 8?

The validators are the bridge’s own signers: eight addresses listed in a validator contract on each chain, five of which must agree before a message counts (who can change what). A threshold means no single validator can approve a transfer alone, and a few can be offline without stopping the bridge. The list and the threshold are settings, read on 2026-10-17.

Where does the trust sit?

In two places. First, the validators: tokens locked on Ethereum are safe as long as fewer than 5 of the 8 validator keys are misused. Second, the admin keys: on 2026-10-17 every contract owner and every upgrade owner of the bridge was a single key, and the code lets such a key redirect a contract, change the validators or replace the code — each of which could bypass the 5-of-8 rule; the owner of the Ethereum token mediator could also move locked tokens into an outside interest contract. On that date, and again on 2026-10-19, all settings pointed to the bridge’s own contracts and no interest contract was set. Whether the keys are protected off-chain cannot be seen from the chain. The full readings, addresses and audits are on the bridge.

What follows for you: a bridged token is only as good as the vault behind it, so bridge what you need, check the address of the token you receive, and open the bridge from a bookmark — look-alike bridge sites are a common scam (Security).

How long does it take and what does it cost?

Fees and confirmation counts are settings the bridge owners can change; the bridge lists the exact readings and the contracts they come from.