@metamask/snaps-rpc-methods
Version:
MetaMask Snaps JSON-RPC method implementations
128 lines • 5.12 kB
JavaScript
import { BIP44CoinTypeNode } from "@metamask/key-tree";
import { PermissionType, SubjectType } from "@metamask/permission-controller";
import { rpcErrors } from "@metamask/rpc-errors";
import { SnapCaveatType } from "@metamask/snaps-utils";
import { getMnemonicSeed, getValueFromEntropySource } from "../utils.mjs";
const targetName = 'snap_getBip44Entropy';
/**
* The specification builder for the `snap_getBip44Entropy` permission.
* `snap_getBip44Entropy_*` lets the Snap control private keys for a particular
* BIP-32 coin type.
*
* @param options - The specification builder options.
* @param options.messenger - The messenger.
* @param options.methodHooks - The RPC method hooks needed by the method
* implementation.
* @returns The specification for the `snap_getBip44Entropy` permission.
*/
const specificationBuilder = ({ methodHooks, messenger, }) => {
return {
permissionType: PermissionType.RestrictedMethod,
targetName,
allowedCaveats: [SnapCaveatType.PermittedCoinTypes],
methodImplementation: getBip44EntropyImplementation({
methodHooks,
messenger,
}),
validator: ({ caveats }) => {
if (caveats?.length !== 1 ||
caveats[0].type !== SnapCaveatType.PermittedCoinTypes) {
throw rpcErrors.invalidParams({
message: `Expected a single "${SnapCaveatType.PermittedCoinTypes}" caveat.`,
});
}
},
subjectTypes: [SubjectType.Snap],
};
};
const methodHooks = {
getUnlockPromise: true,
getClientCryptography: true,
};
/**
* Enables you to [manage users' non-EVM accounts](https://docs.metamask.io/snaps/features/non-evm-networks/)
* by deriving the [BIP-44](https://github.com/bitcoin/bips/blob/master/bip-0044.mediawiki)
* keys specified by the `coinType` parameter. The keys are derived using the
* entropy from the user's Secret Recovery Phrase.
*
* If the keys you want to derive don't conform to the BIP-44 structure, use
* [`snap_getBip32Entropy`](https://docs.metamask.io/snaps/reference/snaps-api/snap_getbip32entropy)
* instead.
*
* This method is designed to be used with the [`@metamask/key-tree`](https://npmjs.com/package/@metamask/key-tree)
* module. `@metamask/key-tree` can help you get the [extended private keys](https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki#extended-keys)
* for user addresses, but it's your responsibility to know how to use those
* keys to, for example, derive an address for the relevant protocol or sign a
* transaction for the user.
*
* @example
* ```json name="Manifest"
* {
* "initialPermissions": {
* "snap_getBip44Entropy": [
* {
* "coinType": 3
* }
* ]
* }
* }
* ```
* ```ts name="Usage"
* import { getBIP44AddressKeyDeriver } from '@metamask/key-tree'
*
* // This example uses Dogecoin, which has coin_type 3.
* const dogecoinNode = await snap.request({
* method: 'snap_getBip44Entropy',
* params: {
* coinType: 3,
* },
* })
*
* // Next, create an address key deriver function for the Dogecoin coin_type
* // node. In this case, its path is: m/44'/3'/0'/0/address_index
* const deriveDogecoinAddress = await getBIP44AddressKeyDeriver(dogecoinNode)
*
* // These are BIP-44 nodes containing the extended private keys for the
* // respective derivation paths.
*
* // m/44'/3'/0'/0/0
* const addressKey0 = await deriveDogecoinAddress(0)
*
* // m/44'/3'/0'/0/1
* const addressKey1 = await deriveDogecoinAddress(1)
* ```
*/
export const getBip44EntropyBuilder = Object.freeze({
targetName,
specificationBuilder,
methodHooks,
actionNames: ['KeyringController:withKeyringV2Unsafe'],
});
/**
* Builds the method implementation for `snap_getBip44Entropy`.
*
* @param options - The options.
* @param options.messenger - The messenger.
* @param options.methodHooks - The RPC method hooks.
* @param options.methodHooks.getUnlockPromise - A function that resolves once the MetaMask
* extension is unlocked and prompts the user to unlock their MetaMask if it is
* locked.
* @param options.methodHooks.getClientCryptography - A function to retrieve the cryptographic
* functions to use for the client.
* @returns The method implementation which returns a `BIP44CoinTypeNode`.
* @throws If the params are invalid.
*/
export function getBip44EntropyImplementation({ methodHooks: { getUnlockPromise, getClientCryptography }, messenger, }) {
return async function getBip44Entropy(args) {
await getUnlockPromise(true);
// `args.params` is validated by the decorator, so it's safe to assert here.
const params = args.params;
const seed = await getValueFromEntropySource(getMnemonicSeed.bind(null, messenger), params.source);
const node = await BIP44CoinTypeNode.fromSeed({
derivationPath: [seed, `bip32:44'`, `bip32:${params.coinType}'`],
network: 'mainnet',
}, getClientCryptography());
return node.toJSON();
};
}
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