Stytch SMS OTP

Stytch SMS OTP Authentication uses Stytch’s SMS OTP service to authenticate users through mobile phone verification. This method sends a one-time password (OTP) to your phone number, which you then use to verify your identity and mint a PKP.

Prerequisites

Backend Required: This authentication method requires a backend service that handles Stytch Email OTP operations. The auth service already has the implementation in place with the /stytch/email/send-otp and /stytch/email/verify-otp endpoints, but they are disabled by default. Simply run your auth service at the configured URL to enable Stytch Email OTP functionality.

Lit Auth Server URLs. Please refer to Auth Services section.

1. Send OTP to Phone

   Enter your phone number to receive a one-time password (OTP). The OTP will be sent via Stytch’s SMS service through your backend.

   import { StytchSmsOtpAuthenticator } from "@lit-protocol/auth";
   
   const { methodId } = await StytchSmsOtpAuthenticator.sendOtp({
     phoneNumber: "[phone]",
     authServiceBaseUrl: "https://naga-auth-service.onrender.com",
   });
   

2. Verify OTP

   Enter the OTP code sent to your phone to verify your identity and generate authentication data.

   import { StytchSmsOtpAuthenticator } from "@lit-protocol/auth";
   
   const authData = await StytchSmsOtpAuthenticator.authenticate({
     methodId: methodId, // from sendOtp step
     code: "123456", // user-entered OTP code
     authServiceBaseUrl: "https://naga-auth-service.onrender.com",
   });
   

3. Setup TOTP 2FA (Optional)

   Add an extra layer of security to your account by setting up TOTP (Time-based One-Time Password) 2FA. This will allow you to use authenticator apps like Google Authenticator, Authy, or 1Password for future logins.

   See TOTP 2FA for more details.

4. Get or Mint a PKP

   You can select an existing PKP associated with your account or mint a new one.

   Mint a fresh PKP

   const res = await litClient.authService.mintWithAuth({
     authData: authData,
   });
   

5. Generate Auth Context

   Use your PKP’s public key to create an AuthContext. This method will cache two things:

   1. session key pair - a temporary cryptographic key pair generated on the client side that acts as a temporary identity for the client application. It consists of:
      • A public key - shared with the Lit nodes
      • A secret key (private key) - kept securely on the client
   2. Delegation AuthSig aka. the inner auth sig - a cryptographic attestation from the Lit Protocol nodes that authorises your session key to act on behalf of your PKP.

   const authContext = await authManager.createPkpAuthContext({
     authData: authData, // <-- Retrieved earlier
     pkpPublicKey: pkpInfo.pubkey,
     authConfig: {
       resources: [
         ["pkp-signing", "*"],
         ["lit-action-execution", "*"],
       ],
       expiration: new Date(Date.now() + 1000 * 60 * 60 * 24).toISOString(),
       statement: "",
       domain: window.location.origin,
     },
     litClient: litClient,
   });