XRPL Wallet Kit

Appearance

Custom Backend (Express) ​

Integrate Sign In with XRPL Wallet into an existing Express server. This guide covers nonce generation, message validation, signature verification, and session management with express-session.

Install ​

sh
# On your server — NOT the browser bundle
npm install @xrpl-wallet-kit/auth
npm install ripple-keypairs verify-xrpl-signature xrpl
npm install express express-session

Server setup ​

Create the verifier ​

Create the verifier once when the server starts. It holds a WebSocket connection to an XRPL node for signedTx verification.

ts
// auth/verifier.ts (or auth/verifier.js)
import { createXrplSignatureVerifier } from "@xrpl-wallet-kit/auth/verifiers";

export const verifier = createXrplSignatureVerifier({
  nodeUrl: process.env.XRPL_NODE_URL ?? "wss://xrplcluster.com",
  // connectTimeoutMs: 8000,  // optional, default 8000
  // requestTimeoutMs: 10000, // optional, default 10000
});

Auth routes ​

ts
// auth/routes.ts
import { Router, type Request, type Response } from "express";
import {
  generateNonce,
  parseAuthMessage,
  validateAuthMessage,
} from "@xrpl-wallet-kit/auth";
import { verifier } from "./verifier";

const router = Router();

// ── GET /api/auth/nonce ─────────────────────────────────────────
// Issues a fresh nonce and stores it in the server session.
// Client must call this first, then build the sign-in message.
router.get("/nonce", async (req: Request, res: Response) => {
  const nonce = generateNonce();   // 16-byte hex, crypto-secure

  req.session.pendingNonce = nonce;
  req.session.nonceIssuedAt = Date.now();

  res.json({ nonce });
});

// ── POST /api/auth/verify ───────────────────────────────────────
// Verifies the signed message and creates an authenticated session.
router.post("/verify", async (req: Request, res: Response) => {
  const {
    message,
    signatureKind,    // "signature" | "signedTx"
    signature,        // compact sig (GemWallet, Crossmark, DropFi)
    txBlob,           // signed tx blob (Xaman, WalletConnect, XRPL Snap)
    address,
    publicKey,        // optional — forwarded when adapter provides it
  } = req.body;

  // 1 — Nonce must exist
  if (!req.session.pendingNonce) {
    return res.status(400).json({ error: "No pending nonce. Request /nonce first." });
  }

  // Optional: reject stale nonces older than 5 minutes
  if (req.session.nonceIssuedAt && Date.now() - req.session.nonceIssuedAt > 5 * 60 * 1000) {
    req.session.pendingNonce = undefined;
    return res.status(400).json({ error: "Nonce expired." });
  }

  // 2 — Parse the message
  let parsed: ReturnType<typeof parseAuthMessage>;
  try {
    parsed = parseAuthMessage(message);
  } catch {
    return res.status(400).json({ error: "Invalid message format." });
  }

  // 3 — Validate domain, age, nonce
  const { valid, reason } = validateAuthMessage(parsed, {
    expectedDomain: req.hostname,                      // e.g. "myapp.com"
    maxAge: 300,                                       // 5 minutes
    usedNonces: new Set([req.session.pendingNonce]),
  });

  if (!valid) {
    return res.status(400).json({ error: reason });
  }

  // 4 — Verify cryptographic signature
  //     verifier branches automatically on signatureKind
  try {
    const ok = await verifier.verify({
      message,
      signatureKind,
      signature,
      txBlob,
      address,
      publicKey,
    });

    if (!ok) {
      return res.status(401).json({ error: "Signature verification failed." });
    }
  } catch (err) {
    console.error("[auth/verify] verifier error:", err);
    return res.status(500).json({ error: "Verification service unavailable." });
  }

  // 5 — Mark session as authenticated
  req.session.pendingNonce = undefined;   // one-time use — invalidate
  req.session.address = address;
  req.session.authenticatedAt = Date.now();

  res.json({ ok: true, address });
});

// ── POST /api/auth/signout ──────────────────────────────────────
router.post("/signout", (req: Request, res: Response) => {
  req.session.destroy((err) => {
    if (err) console.error("[auth/signout]", err);
    res.clearCookie("connect.sid");
    res.json({ ok: true });
  });
});

export default router;

Express app ​

ts
// server.ts
import express from "express";
import session from "express-session";
import authRouter from "./auth/routes";

const app = express();
app.use(express.json());

app.use(
  session({
    secret: process.env.SESSION_SECRET!,   // min 32 random chars
    resave: false,
    saveUninitialized: false,
    cookie: {
      httpOnly: true,
      secure: process.env.NODE_ENV === "production",
      sameSite: "lax",
      maxAge: 30 * 60 * 1000,   // 30 minutes
    },
  })
);

// Mount auth routes
app.use("/api/auth", authRouter);

// Example protected route
app.get("/api/me", requireAuth, (req, res) => {
  res.json({ address: req.session.address });
});

function requireAuth(req: any, res: any, next: any) {
  if (!req.session?.address) {
    return res.status(401).json({ error: "Not authenticated." });
  }
  next();
}

app.listen(3000);

TypeScript session augmentation ​

ts
// types/express-session.d.ts
import "express-session";

declare module "express-session" {
  interface SessionData {
    pendingNonce?: string;
    nonceIssuedAt?: number;
    address?: string;
    authenticatedAt?: number;
  }
}

Client-side WalletAuthAdapter ​

The adapter is what connects your frontend to the routes above.

ts
// src/wallet-auth-adapter.ts
import { formatAuthMessage, type WalletAuthAdapter } from "@xrpl-wallet-kit/auth";

export const walletAuthAdapter: WalletAuthAdapter = {
  async getNonce() {
    const res = await fetch("/api/auth/nonce");
    if (!res.ok) throw new Error("Failed to get nonce.");
    const { nonce } = await res.json();
    return nonce as string;
  },

  createMessage(params) {
    // Use the built-in formatter or write your own string
    return formatAuthMessage(params);
  },

  async verify(params) {
    const res = await fetch("/api/auth/verify", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(params),
    });
    // Return true if server accepted the proof
    return res.ok;
  },

  async signOut() {
    await fetch("/api/auth/signout", { method: "POST" });
  },
};

Then wire it up:

ts
import { createWalletAuth } from "@xrpl-wallet-kit/auth";
import { walletAuthAdapter } from "./wallet-auth-adapter";

// manager comes from createWalletKit() or WalletManager
const auth = createWalletAuth(manager, walletAuthAdapter, {
  chainId: "xrpl:0",
  statement: "Sign in to MyApp.",
  expiresIn: 3600,
});

await auth.signIn();

Production checklist ​

  • SESSION_SECRET — at least 32 random characters, stored in an environment variable, never committed.
  • Redis session store — swap the default MemoryStore for connect-redis in production. MemoryStore leaks memory and does not survive restarts.
  • HTTPS only — set cookie.secure: true and serve behind a TLS terminator.
  • Rate-limit /api/auth/nonce — prevents nonce exhaustion attacks. Add express-rate-limit to the nonce endpoint.
  • Nonce TTL — reject nonces older than 5 minutes (example above already does this).
  • XRPL node — prefer a private or dedicated node (wss://s1.ripple.com, Ripple's infra) over public clusters for reliability.

See also ​

Released under the MIT License.

Copyright © 2026 XRPL Wallet Kit Contributors