Add RemoteEOA signer (#121)

Author: hazim-j

src/preset/builder/simpleAccount.ts

@@ -15,10 +15,14 @@ import {
   SimpleAccount as SimpleAccountImpl,
   SimpleAccount__factory,
 } from "../../typechain";
-import { IPresetBuilderOpts, UserOperationMiddlewareFn } from "../../types";
+import {
+  EOASigner,
+  IPresetBuilderOpts,
+  UserOperationMiddlewareFn,
+} from "../../types";
 
 export class SimpleAccount extends UserOperationBuilder {
-  private signer: ethers.Signer;
+  private signer: EOASigner;
   private provider: ethers.providers.JsonRpcProvider;
   private entryPoint: EntryPoint;
   private factory: SimpleAccountFactory;
@@ -27,7 +31,7 @@ export class SimpleAccount extends UserOperationBuilder {
   proxy: SimpleAccountImpl;
 
   private constructor(
-    signer: ethers.Signer,
+    signer: EOASigner,
     rpcUrl: string,
     opts?: IPresetBuilderOpts
   ) {
@@ -62,7 +66,7 @@ export class SimpleAccount extends UserOperationBuilder {
   };
 
   public static async init(
-    signer: ethers.Signer,
+    signer: EOASigner,
     rpcUrl: string,
     opts?: IPresetBuilderOpts
   ): Promise<SimpleAccount> {
@@ -89,7 +93,7 @@ export class SimpleAccount extends UserOperationBuilder {
     const base = instance
       .useDefaults({
         sender: instance.proxy.address,
-        signature: await instance.signer.signMessage(
+        signature: await ethers.Wallet.createRandom().signMessage(
           ethers.utils.arrayify(ethers.utils.keccak256("0xdead"))
         ),
       })

src/preset/signers/index.ts

@@ -1 +1,2 @@
 export * from "./barzSecp256r1";
+export * from "./remoteEOA";

src/preset/signers/remoteEOA.ts

@@ -0,0 +1,28 @@
+import { Bytes, ethers } from "ethers";
+import { EOASigner } from "../../types";
+
+export class RemoteEOA implements EOASigner {
+  public provider: ethers.providers.JsonRpcProvider;
+
+  constructor(url: string) {
+    this.provider = new ethers.providers.JsonRpcProvider(url);
+  }
+
+  getAddress(): Promise<string> {
+    return this.provider.getSigner().getAddress();
+  }
+
+  async signMessage(message: string | Bytes): Promise<string> {
+    const signer = this.provider.getSigner();
+    let signature = await signer.signMessage(message);
+
+    // Code snippet from https://gist.github.com/kalaspuff/19365e21e01929c79d5d2638c1ee580e
+    // See also https://github.com/ethereum/go-ethereum/issues/19751#issuecomment-504900739
+    if (/(^0[xX]|^)[0-9a-fA-F]{128}(00|01)$/.test(signature)) {
+      const sigV = (parseInt(signature.slice(-2), 16) + 27).toString(16);
+      signature = signature.slice(0, -2) + sigV;
+    }
+
+    return signature;
+  }
+}

src/types.ts

@@ -67,6 +67,8 @@ export interface IPresetBuilderOpts {
 // eslint-disable-next-line @typescript-eslint/no-empty-interface
 export interface ISigner extends Pick<ethers.Signer, "signMessage"> {}
 
+export type EOASigner = ISigner & Pick<ethers.Signer, "getAddress">;
+
 export interface ICall {
   to: string;
   value: BigNumberish;