Introduction

Send assets across chains with a Railgun privacy hop between the public deposit and payout legs. Erebuz handles bridging through Relay by default (or Circle CCTP in USDC-only deployments), privacy through Railgun, and orchestration through a TEE.

wall8 is the reference app built on the protocol.

How a transfer works

The protocol moves value through three legs:

1. Bridge to the hub. The source asset is bridged or swapped into the configured hub asset on Arbitrum. The sender funds a route-specific deposit address.
2. Shield and unshield. The hub asset is shielded into Railgun and later unshielded for the outbound leg. This breaks the direct public on-chain link between the two legs.
3. Bridge to the destination. The unshielded asset is bridged or swapped into the requested destination asset and delivered to the recipient.

The TEE handles everything after the deposit.

Privacy model

An observer sees public activity on the source, hub, and destination chains. The shielded pool sits between the public bridge legs so they cannot be linked by a simple transaction trace.

The TEE knows the full route. Privacy is against outside observers, not the operator.

Fee breakdown

The service fee is charged on the destination-side output:

• Service fee: max($1, 1.5%)

In Relay mode, provider costs are already reflected in Relay's expected output and the separate bridge/privacy fee fields are zero or unavailable. In CCTP mode, the quote also itemizes the Railgun unshield fee and estimated destination CCTP fee.

Supported chains

Coverage depends on BRIDGE_PROVIDER. Relay mode discovers deposit-address-enabled chains and currencies dynamically. CCTP mode exposes the configured Circle networks and USDC only.

List available chains and tokens:

curl $BASE_URL/api/relay/chains
curl "$BASE_URL/api/relay/tokens?chainId=42161&search=USDC"

See Supported chains for the provider-specific behavior.

Next

Quickstart: quote, create, and track a transfer. Reference: endpoints, fields, and statuses.