Implement personal_sign (#2095)

* Add sign message

* Update packages/fcl-ethereum-provider/src/accounts/account-manager.ts

Co-authored-by: Jordan Ribbink <[email protected]>

* Push fix

* Remove comment

* Update packages/fcl-ethereum-provider/src/rpc/handlers/personal-sign.ts

Co-authored-by: Jordan Ribbink <[email protected]>

* Update packages/fcl-ethereum-provider/src/accounts/account-manager.ts

Co-authored-by: Jordan Ribbink <[email protected]>

* Update packages/fcl-ethereum-provider/src/rpc/handlers/personal-sign.ts

Co-authored-by: Jordan Ribbink <[email protected]>

* Check auth with coa address

* Add tests

* Fix params and prettier

* Run prettier

* Use RLP

* Change path

* hex array

* Fix RLP test

* Run prettier

---------

Co-authored-by: Chase Fleming <[email protected]>
Co-authored-by: Jordan Ribbink <[email protected]>

packages/fcl-ethereum-provider/package.json

@@ -38,6 +38,7 @@
   "dependencies": {
     "@babel/runtime": "^7.25.7",
     "@onflow/fcl": "1.13.4",
+    "@onflow/rlp": "^1.2.3",
     "@walletconnect/jsonrpc-http-connection": "^1.0.8",
     "@walletconnect/jsonrpc-provider": "^1.0.14"
   }

packages/fcl-ethereum-provider/src/accounts/account-manager.test.ts

@@ -1,6 +1,7 @@
 import {AccountManager} from "./account-manager"
 import {mockUser} from "../__mocks__/fcl"
 import * as fcl from "@onflow/fcl"
+import * as rlp from "@onflow/rlp"
 import {CurrentUser} from "@onflow/typedefs"
 
 jest.mock("@onflow/fcl", () => {
@@ -14,6 +15,11 @@ jest.mock("@onflow/fcl", () => {
   }
 })
 
+jest.mock("@onflow/rlp", () => ({
+  encode: jest.fn(),
+  Buffer: jest.requireActual("@onflow/rlp").Buffer,
+}))
+
 const mockFcl = jest.mocked(fcl)
 const mockQuery = jest.mocked(fcl.query)
 
@@ -333,3 +339,82 @@ describe("send transaction", () => {
     )
   })
 })
+
+describe("signMessage", () => {
+  let accountManager: AccountManager
+  let user: jest.Mocked<typeof fcl.currentUser>
+
+  beforeEach(() => {
+    user = mockUser()
+    accountManager = new AccountManager(user)
+  })
+
+  afterEach(() => {
+    jest.clearAllMocks()
+  })
+
+  it("should throw an error if the COA address is not available", async () => {
+    accountManager["coaAddress"] = null
+
+    await expect(
+      accountManager.signMessage("Test message", "0x1234")
+    ).rejects.toThrow(
+      "COA address is not available. User might not be authenticated."
+    )
+  })
+
+  it("should throw an error if the signer address does not match the COA address", async () => {
+    accountManager["coaAddress"] = "0xCOA1"
+
+    await expect(
+      accountManager.signMessage("Test message", "0xDIFFERENT")
+    ).rejects.toThrow("Signer address does not match authenticated COA address")
+  })
+
+  it("should successfully sign a message and return an RLP-encoded proof", async () => {
+    accountManager["coaAddress"] = "0xCOA1"
+    const mockSignature = "0xabcdef1234567890"
+    const mockRlpEncoded = "f86a808683abcdef682f73746f726167652f65766d"
+
+    user.signUserMessage = jest
+      .fn()
+      .mockResolvedValue([{addr: "0xCOA1", keyId: 0, signature: mockSignature}])
+
+    jest.mocked(rlp.encode).mockReturnValue(Buffer.from(mockRlpEncoded, "hex"))
+
+    const proof = await accountManager.signMessage("Test message", "0xCOA1")
+
+    expect(proof).toBe(`0x${mockRlpEncoded}`)
+
+    expect(user.signUserMessage).toHaveBeenCalledWith("Test message")
+
+    expect(rlp.encode).toHaveBeenCalledWith([
+      [0],
+      expect.any(Buffer),
+      "/public/evm",
+      [mockSignature],
+    ])
+  })
+
+  it("should throw an error if signUserMessage returns an empty array", async () => {
+    accountManager["coaAddress"] = "0xCOA1"
+
+    user.signUserMessage = jest.fn().mockResolvedValue([])
+
+    await expect(
+      accountManager.signMessage("Test message", "0xCOA1")
+    ).rejects.toThrow("Failed to sign message")
+  })
+
+  it("should throw an error if signUserMessage fails", async () => {
+    accountManager["coaAddress"] = "0xCOA1"
+
+    user.signUserMessage = jest
+      .fn()
+      .mockRejectedValue(new Error("Signing failed"))
+
+    await expect(
+      accountManager.signMessage("Test message", "0xCOA1")
+    ).rejects.toThrow("Signing failed")
+  })
+})

packages/fcl-ethereum-provider/src/accounts/account-manager.ts

@@ -1,5 +1,6 @@
 import * as fcl from "@onflow/fcl"
-import {CurrentUser} from "@onflow/typedefs"
+import * as rlp from "@onflow/rlp"
+import {CompositeSignature, CurrentUser} from "@onflow/typedefs"
 import {
   ContractType,
   EVENT_IDENTIFIERS,
@@ -9,6 +10,7 @@ import {
   FlowNetwork,
 } from "../constants"
 import {TransactionExecutedEvent} from "../types/events"
+import {EthSignatureResponse} from "../types/eth"
 
 export class AccountManager {
   private user: typeof fcl.currentUser
@@ -194,4 +196,45 @@ export class AccountManager {
 
     return evmTxHash
   }
+
+  public async signMessage(
+    message: string,
+    from: string
+  ): Promise<EthSignatureResponse> {
+    if (!this.coaAddress) {
+      throw new Error(
+        "COA address is not available. User might not be authenticated."
+      )
+    }
+
+    if (from.toLowerCase() !== this.coaAddress.toLowerCase()) {
+      throw new Error("Signer address does not match authenticated COA address")
+    }
+
+    try {
+      const response: CompositeSignature[] =
+        await this.user.signUserMessage(message)
+
+      if (!response || response.length === 0) {
+        throw new Error("Failed to sign message")
+      }
+
+      const keyIndices = response.map(sig => sig.keyId)
+      const signatures = response.map(sig => sig.signature)
+
+      const addressHexArray = Buffer.from(from.replace(/^0x/, ""), "hex")
+
+      const capabilityPath = "/public/evm"
+
+      const rlpEncodedProof = rlp
+        .encode([keyIndices, addressHexArray, capabilityPath, signatures])
+        .toString("hex")
+
+      return rlpEncodedProof.startsWith("0x")
+        ? rlpEncodedProof
+        : `0x${rlpEncodedProof}` // Return 0x-prefix for Ethereum compatibility
+    } catch (error) {
+      throw error
+    }
+  }
 }

packages/fcl-ethereum-provider/src/rpc/handlers/personal-sign.ts

@@ -0,0 +1,11 @@
+import {AccountManager} from "../../accounts/account-manager"
+import {PersonalSignParams} from "../../types/eth"
+
+export async function personalSign(
+  accountManager: AccountManager,
+  params: PersonalSignParams
+) {
+  const [message, from] = params
+
+  return await accountManager.signMessage(message, from)
+}

packages/fcl-ethereum-provider/src/rpc/rpc-processor.ts

@@ -5,6 +5,8 @@ import {AccountManager} from "../accounts/account-manager"
 import * as fcl from "@onflow/fcl"
 import {FLOW_CHAINS, FlowNetwork} from "../constants"
 import {ethSendTransaction} from "./handlers/eth-send-transaction"
+import {personalSign} from "./handlers/personal-sign"
+import {PersonalSignParams} from "../types/eth"
 
 export class RpcProcessor {
   constructor(
@@ -26,6 +28,11 @@ export class RpcProcessor {
         return ethRequestAccounts(this.accountManager)
       case "eth_sendTransaction":
         return await ethSendTransaction(this.accountManager, params)
+      case "personal_sign":
+        return await personalSign(
+          this.accountManager,
+          params as PersonalSignParams
+        )
       default:
         return await this.gateway.request({
           chainId: eip155ChainId,

packages/fcl-ethereum-provider/src/types/eth.ts

@@ -0,0 +1,3 @@
+export type EthSignatureResponse = string
+
+export type PersonalSignParams = [string, string]