melonask/universal-signer-skills

Overview

This skill guides developers to use @universal-signer/core to provide a single, type-safe signing interface for AWS KMS, GCP KMS, Ledger, Trezor, Turnkey, and local accounts with Viem v2. It shows how to configure provider-specific accounts, create a Viem-compatible client, and sign transactions, messages, and EIP-712 typed data. The guide emphasizes consistent signature normalization and built-in hardware wallet handling.

How this skill works

The library exposes factory functions to create provider-specific accounts (AWS, GCP, Ledger, Trezor, Turnkey, Local) that implement a Viem LocalAccount. You pass the created account and chain/http transport to createUniversalClient to obtain a Viem-compatible client. The client delegates signTransaction, signMessage, and signTypedData calls to the underlying provider while normalizing KMS signatures and handling hardware transport details.

When to use it

• You need one code path that can switch between cloud KMS, hardware wallets, or local keys.
• Building infrastructure that must support multiple signing backends for different environments.
• Implementing secure signing in server-side apps using AWS KMS or GCP KMS.
• Integrating hardware wallets (Ledger, Trezor) in desktop or server contexts with HID handling.
• Using Turnkey or local private keys for development and testing with the same API.

Best practices

• Install only the provider packages you need to minimize dependencies and attack surface.
• Keep KMS keys and access scoped with least privilege; prefer aliases or key IDs for clarity.
• Use the unified Viem client for all blockchain interactions to avoid provider-specific branching.
• Validate signature flow in staging with the same provider types as production (hardware vs cloud).
• Enable and test signature normalization and recovery logic when using cloud KMS providers.

Example use cases

• A backend service that signs transactions with AWS KMS in production and local keys in CI.
• A multiservice platform that offers customer-managed keys hosted in GCP KMS or Turnkey.
• A desktop wallet app that supports Ledger and Trezor via the same signing interface.
• A migration plan to move signing from local keys to cloud KMS without changing application code.
• Integration tests that exercise signTypedData (EIP-712) across all supported providers.