feat: ethereum wallet signer utility (#230)

src/utils/eth.ts

@@ -1,7 +1,8 @@
 import { keccak256, sha3_256 } from 'js-sha3'
-import { BrandedString } from '../types'
+import { BrandedString, Data } from '../types'
 import { HexString, hexToBytes, intToHex, makeHexString, assertHexString } from './hex'
 import { Bytes, verifyBytes } from './bytes'
+import { Signer } from '../chunk/signer'
 
 export type OverlayAddress = BrandedString<'OverlayAddress'>
 export type EthAddress = Bytes<20>
@@ -167,3 +168,60 @@ export function ethToSwarmAddress(ethAddress: string | HexString | HexEthAddress
 
   return overlayAddress as OverlayAddress
 }
+
+interface RequestArguments {
+  method: string
+  jsonrpc?: string
+  params?: unknown[] | Record<string, unknown>
+}
+
+export interface JsonRPC {
+  request?(args: RequestArguments): Promise<unknown>
+  sendAsync?(args: RequestArguments): Promise<unknown>
+}
+
+/**
+ * Function that takes Ethereum EIP-1193 compatible provider and create an Signer instance that
+ * uses personal_sign method to sign requested data.
+ *
+ * @param provider Injected web3 provider like window.ethereum or other compatible with EIP-1193
+ * @param ethAddress Optional address of the account which the data should be signed with. If not specified eth_requestAccounts requests is used to get the account address.
+ */
+export async function makeEthereumWalletSigner(
+  provider: JsonRPC,
+  ethAddress?: string | HexString | HexEthAddress,
+): Promise<Signer> {
+  let executorFnc: (args: RequestArguments) => Promise<unknown>
+
+  if (typeof provider !== 'object' || provider === null) {
+    throw new TypeError('We need JsonRPC provider object!')
+  }
+
+  if (provider.request) {
+    executorFnc = provider.request
+  } else if (provider.sendAsync) {
+    executorFnc = provider.sendAsync
+  } else {
+    throw new Error('Incompatible interface of given provider!')
+  }
+
+  if (!ethAddress) {
+    ethAddress = ((await executorFnc({ method: 'eth_requestAccounts' })) as string[])[0]
+  }
+
+  const bytesEthAddress = makeEthAddress(ethAddress)
+  const hexEthAddress = makeHexEthAddress(ethAddress)
+
+  return {
+    address: bytesEthAddress,
+    sign: async (data: Data): Promise<string> => {
+      const result = await executorFnc({
+        jsonrpc: '2.0',
+        method: 'personal_sign',
+        params: ['0x' + data.hex(), '0x' + hexEthAddress],
+      })
+
+      return result as string
+    },
+  } as Signer
+}

test/utils/eth.spec.ts

@@ -1,5 +1,14 @@
 /* eslint @typescript-eslint/no-empty-function: 0 */
-import { ethToSwarmAddress, fromLittleEndian, isHexEthAddress, toLittleEndian } from '../../src/utils/eth'
+import {
+  makeEthereumWalletSigner,
+  ethToSwarmAddress,
+  fromLittleEndian,
+  isHexEthAddress,
+  JsonRPC,
+  toLittleEndian,
+} from '../../src/utils/eth'
+import { HexString, hexToBytes } from '../../src/utils/hex'
+import { wrapBytesWithHelpers } from '../../src/utils/bytes'
 
 describe('eth', () => {
   describe('isEthAddress', () => {
@@ -137,4 +146,78 @@ describe('eth', () => {
       }),
     )
   })
+
+  describe('makeEthereumWalletSigner', () => {
+    const dataToSignBytes = hexToBytes('2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae' as HexString)
+    const dataToSignWithHelpers = wrapBytesWithHelpers(dataToSignBytes)
+    const expectedSignatureHex = '0x336d24afef78c5883b96ad9a62552a8db3d236105cb059ddd04dc49680869dc16234f6852c277087f025d4114c4fac6b40295ecffd1194a84cdb91bd571769491b' as HexString
+
+    it('should detect valid interface', async () => {
+      await expect(makeEthereumWalletSigner({})).rejects.toThrow()
+      await expect(makeEthereumWalletSigner(('' as unknown) as JsonRPC)).rejects.toThrow(TypeError)
+      await expect(makeEthereumWalletSigner((1 as unknown) as JsonRPC)).rejects.toThrow(TypeError)
+      await expect(makeEthereumWalletSigner((null as unknown) as JsonRPC)).rejects.toThrow(TypeError)
+      await expect(makeEthereumWalletSigner((undefined as unknown) as JsonRPC)).rejects.toThrow(TypeError)
+    })
+
+    it('should request address if not specified', async () => {
+      const providerMock = jest.fn()
+      providerMock.mockReturnValue(['0xf1B07aC6E91A423d9c3c834cc9d938E89E19334a'])
+
+      const signer = await makeEthereumWalletSigner({ request: providerMock } as JsonRPC)
+
+      expect(signer.address).toEqual(hexToBytes('f1B07aC6E91A423d9c3c834cc9d938E89E19334a'))
+      expect(providerMock.mock.calls.length).toEqual(1)
+      expect(providerMock.mock.calls[0][0]).toEqual({ method: 'eth_requestAccounts' })
+    })
+
+    it('should request signature when sign() is called', async () => {
+      const providerMock = jest.fn()
+      providerMock.mockReturnValue(expectedSignatureHex)
+
+      const signer = await makeEthereumWalletSigner(
+        { request: providerMock } as JsonRPC,
+        '0xf1B07aC6E91A423d9c3c834cc9d938E89E19334a',
+      )
+      await expect(signer.sign(dataToSignWithHelpers)).resolves.toEqual(expectedSignatureHex)
+      expect(providerMock.mock.calls.length).toEqual(1)
+      expect(providerMock.mock.calls[0][0]).toEqual({
+        jsonrpc: '2.0',
+        method: 'personal_sign',
+        params: [
+          '0x2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae',
+          '0xf1B07aC6E91A423d9c3c834cc9d938E89E19334a',
+        ],
+      })
+    })
+
+    it('should normalize hex prefix for address', async () => {
+      const providerMock = jest.fn()
+      providerMock.mockReturnValue(expectedSignatureHex)
+
+      const signer = await makeEthereumWalletSigner(
+        { request: providerMock } as JsonRPC,
+        'f1B07aC6E91A423d9c3c834cc9d938E89E19334a',
+      )
+      await expect(signer.sign(dataToSignWithHelpers)).resolves.toEqual(expectedSignatureHex)
+      expect(providerMock.mock.calls.length).toEqual(1)
+      expect(providerMock.mock.calls[0][0]).toEqual({
+        jsonrpc: '2.0',
+        method: 'personal_sign',
+        params: [
+          '0x2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae',
+          '0xf1B07aC6E91A423d9c3c834cc9d938E89E19334a',
+        ],
+      })
+    })
+
+    it('should validate eth address', async () => {
+      const providerMock = jest.fn()
+      providerMock.mockReturnValue(expectedSignatureHex)
+
+      await expect(
+        makeEthereumWalletSigner({ request: providerMock } as JsonRPC, '0x307aC6E91A423d9c3c834cc9d938E89E19334a'),
+      ).rejects.toThrow(TypeError)
+    })
+  })
 })