Silent Data Providers - Custom RPC Package

Table of Contents

• Introduction
• Prerequisites
• Integration
  • Custom RPC Integration
    • Installing Custom RPC Dependencies
    • Custom RPC Integration Example
• Troubleshooting
• License
• Additional Resources

Introduction

Custom RPC is the Silent Data privacy-enforcement RPC gateway (firewall). It sits between clients and an EVM node and:

• enforces a strict method + parameter whitelist (everything else is rejected);
• recovers the request signer (EIP-191, EIP-712, ephemeral-key delegation, and ERC-1271 smart-wallet signatures) and applies signer-based access control;
• redacts sensitive fields from eth_getTransactionByHash / eth_getTransactionReceipt responses for unauthorized callers;
• filters private-event logs (eth_getLogs / eth_getFilterLogs / eth_getFilterChanges) so only allowedViewers see them;
• limits the eth_getLogs block range;
• restricts eth_getBlockBy* to header-only (no full transaction objects);
• handles the custom sd_getVersion and sd_getTransactionsByAddress methods.

It can be used both as a local development environment (in front of a Hardhat node) and as a standalone gateway in front of any EVM node.

Prerequisites

• Node.js (version 20 or higher)
• pnpm
• Basic knowledge of Ethereum and smart contracts
• Hardhat (for local development)

Integration

Custom RPC Integration

Installing Custom RPC Dependencies

pnpm add @appliedblockchain/silentdatarollup-custom-rpc

Custom RPC Integration Example

The Custom RPC package provides a local development environment that integrates Silent Data with a local Hardhat node. To start the development environment:

pnpm dev

This command will start both a Hardhat node and the Custom RPC server concurrently. The Custom RPC server will proxy requests to the Hardhat node while adding Silent Data functionality.

Running the server standalone

Installing the package also provides a silentdatarollup-custom-rpc binary that starts the gateway:

silentdatarollup-custom-rpc
# or, within a workspace:  pnpm exec silentdatarollup-custom-rpc

By default it listens on port 54321 and proxies to http://localhost:8545.

Configuration

Configure the server with environment variables (a .env file in the working directory is loaded automatically):

| Variable | Default | Description | | ----------------------------------- | ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------ | | CUSTOM_RPC_PORT | 54321 | Port the gateway listens on. | | CUSTOM_RPC_PROXY_URL | http://localhost:8545 | URL of the backing EVM node requests are proxied to. | | CUSTOM_RPC_LOGS_LIMIT_RANGE | 10000 | Maximum block range allowed for a single eth_getLogs. | | CUSTOM_RPC_PER_PAGE | 10 | Default page size for sd_getTransactionsByAddress. | | CUSTOM_RPC_BYPASS_METHOD_PREFIXES | (unset) | Comma-separated method-name prefixes that bypass the whitelist (e.g. hardhat,anvil). Dev/test only — do not set in production. |

CUSTOM_RPC_PORT=54321
CUSTOM_RPC_PROXY_URL=http://localhost:8545

Note: contract deployment tooling (Hardhat / Ignition) calls dev-only RPC methods (e.g. hardhat_metadata, hardhat_getAutomine) that are not whitelisted. To deploy through the gateway against a local node, set CUSTOM_RPC_BYPASS_METHOD_PREFIXES=hardhat (dev/test only).

Troubleshooting

If you encounter any issues, please check the following:

1. Ensure Hardhat is properly installed and configured
2. Verify that CUSTOM_RPC_PORT is available
3. Check that the backing node at CUSTOM_RPC_PROXY_URL is running and accessible
4. Ensure all required environment variables are set

License

This project is licensed under the MIT License.

Additional Resources

• Silent Data Documentation
• Hardhat Documentation
• Ethers.js Documentation