ERC-5630 ECDH Snap

Implements the draft ERC-5630 JSON-RPC methods:

- eth_getEncryptionPublicKey → returns a compressed secp256k1 public key for a given Ethereum account.
- eth_performECDH → returns the 32-byte ECDH shared secret x-coordinate for a given account + ephemeral pubkey.

These methods are exposed to dapps via MetaMask Snaps (wallet_invokeSnap).

Install

Once published, dapps can request this snap by Snap ID:

- npm:erc5630-snap

DDRP’s demo site has an install/playground UI:

- https://ddrp.io/#/snap

Permissions

This snap uses:

- endowment:rpc (dapps: true, snaps: false) to expose snap RPC methods via wallet_invokeSnap
- snap_dialog (to show confirmations)
- snap_getBip32Entropy (secp256k1, path prefix m/5630'/0') to derive deterministic per-account encryption keys

snap_getBip32Entropy is a high-privilege permission. Only install/build from sources you trust and only approve
requests from sites you trust.

Limitations

- Derived keys are snap-scoped (from wallet entropy + account string) and are not the account signing key.
- If you restore a different wallet seed phrase, derived encryption keys change.