🤖Captcha Verification

Learn how to integrate Captcha functionality into your Farcaster Frames using the Airstack Frog Recipes.

Step 1: Create Captcha Frames

First, create two new Frames for integrating the captcha:

• /generate-captcha: This Frame will be the 1st entry in the captcha flow to initially generate the captcha challenge that is unique to the user.

• /verify-captcha: This Frame will be the next entry after generating the captcha. In this Frame, the user's answer for the captcha challenge will be validated.

Additionally, add two new fields captchaId and valueHash in the initial state of the Frame that you will be used for the captcha verification.

TypeScript

import { Frog } from "@airstack/frog";

export const app = new Frog({
  // Initialize the Frames state
  initialState: {
    captchaId: "",
    valueHash: "",
  },
});

app.frame("/generate-captcha", async (c) => {});

app.frame("/verify-captcha", async (c) => {});

JavaScript

const { Frog } = require("@airstack/frog");

export const app = new Frog({
  // Initialize the Frames state
  initialState: {
    captchaId: "",
    valueHash: "",
  },
});

app.frame("/generate-captcha", async (c) => {});

app.frame("/verify-captcha", async (c) => {});

Step 2: Generate Captcha Challenge

Then, generate a captcha challenge using the generatedCaptchaChallenge function in the /generate-captcha Frame.

The function will help you randomly generate two integers for your users, which they will need to provide the correct sum result for verification.

In addition to the two integers, a template Frame image will be given along with the hashed sum results in the state field. The state field should be stored in the Frame state.

TypeScript

import { generateCaptchaChallenge } from "@airstack/frog";

app.frame("/generate-captcha", async (c) => {
  const { deriveState } = c ?? {};
  const { data, state, image } = await generateCaptchaChallenge();
  // The 2 numbers generated can be used to generate custom Frame image
  const { numA, numB } = data ?? {};
  deriveState((previousState) => {
    // Store `state` data into Frames state
    previousState.captchaId = state.captchaId;
    previousState.valueHash = state.valueHash;
  });
  return c.res({
    image, // Use template Frame image
    intents: [
      <TextInput placeholder="Type Here!" />,
      <Button action="/verify-captcha">Verify</Button>,
    ],
  });
});

JavaScript

const { generateCaptchaChallenge } = require("@airstack/frog");

app.frame("/generate-captcha", async (c) => {
  const { deriveState } = c ?? {};
  const { data, state, image } = await generateCaptchaChallenge();
  // The 2 numbers generated can be used to generate custom Frame image
  const { numA, numB } = data ?? {};
  deriveState((previousState) => {
    // Store `state` data into Frames state
    previousState.captchaId = state.captchaId;
    previousState.valueHash = state.valueHash;
  });
  return c.res({
    image, // Use template Frame image
    intents: [
      <TextInput placeholder="Type Here!" />,
      <Button action="/verify-captcha">Verify</Button>,
    ],
  });
});

In the Frame, it will also render a text input for user to input the captcha answer and a Verify button to go to the next Frame /verify-captcha for captcha validation.

Step 3: Verify Captcha Challenge

Once the user clicked on the Verify button, they will be redirected to the /verify-captcha Frame where validateCaptchaChallenge function will be called to validate the user's captcha answer with the Frame state (generated from generateCaptchaChallenge).

If the validation is successful, isValidated field will return true. Otherwise, false.

Similarly, you can use the image field for the Farcaster Frame image, which will provide you a template verification image from Airstack.

TypeScript

import { validateCaptchaChallenge } from "@airstack/frog";

app.frame("/verify-captcha", async (c) => {
  const { inputText, deriveState } = c ?? {};
  const state = deriveState() ?? {};
  const { isValidated, image } = await validateCaptchaChallenge({
    inputText,
    state,
  });
  deriveState((previousState) => {
    // Clear Frames state
    previousState.captchaId = "";
    previousState.valueHash = "";
  });
  return c.res({
    image,
    intents: [
      <Button action={isValidated ? "/test" : "/generate-captcha"}>
        {isValidated ? "Continue" : "Try Again?"}
      </Button>,
    ],
  });
});

JavaScript

// Some code

🥳 Congratulations, you've just integrated Captcha into your Farcaster Frames using Airstack Frog Recipes!

Developer Support

If you have any questions or need help integrating Captcha into your Farcaster Frames using the Airstack Frog Recipe, please join our Airstack's Telegram group.

More Resources

• Airstack Frames SDK Refrence

• Farcaster Data

• Farcaster Hubs

• Allow List

• Integrate to Existing Frog Project