Add decryptMessage method

[mikesposito]

Explanation

This PR adds the decryptMessage method needed by extension's DecryptMessageController.

References

• Related to: Add missing methods to KeyringController #1595

Changelog

@metamask/keyring-controller

• ADDED: decryptMessage method

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate

[mikesposito]

Converted to a draft as I'm trying to add a test case as EthKeyringController doesn't have coverage for this method

[mcmire]

One comment!

[mcmire]

Looks good!

[mikesposito]

We could also simplify this by taking inspiration from getEncryptionPublicKey tests, with something like this:

Suggested change

	const { importedAccountAddress } =
	await controller.importAccountWithStrategy(
	AccountImportStrategy.privateKey,
	[privateKey],
	);
	const message = 'Hello, encrypted world!';
	const encryptedMessage = encrypt({
	publicKey: await controller.getEncryptionPublicKey(
	importedAccountAddress,
	),
	data: message,
	version: 'x25519-xsalsa20-poly1305',
	});
	const messageParams = {
	from: importedAccountAddress,
	data: encryptedMessage,
	};
	const result = await controller.decryptMessage(messageParams);
	expect(result).toBe(message);
	const { importedAccountAddress } =
	await controller.importAccountWithStrategy(
	AccountImportStrategy.privateKey,
	[privateKey],
	);
	const result = await controller.decryptMessage({
	from: importedAccountAddress,
	data: {
	version: 'x25519-xsalsa20-poly1305',
	nonce: 'wLwuCz6aY+IjdF34os94LbAer8H5TPck',
	ephemPublicKey: 'B4cLIZfy4AU7xdM8DAO/0+VaIm8W2aY2xb7ciaPmpx8=',
	ciphertext:
	'4mNw0NlJfa+qWAsCza/iYk7uQtYcY/TBLLQnFsPsnS0E7ErjLU8J/ViK',
	},
	});
	expect(result).toBe('My name is Satoshi Buterin');

This would also remove interdependency between unit tests

[cryptodev-2s]

@mikesposito PR got already merged

[mikesposito]

Ops, it got merged while I was reviewing it 😄 nevermind!