Unable to sign-in (SecretHash does not match for the client)

Question

While creating an User pool in cognito, i created a App Client with Client Secret however now while hitting the signin api in postman I am getting an error "SecretHash does not match for the client: hjfuivhioewrjnmcpwoei(dummy)"

However, i have checked my code in every possible scnerio, the client secret, client id, username everything is passed correctly.

Below is my API function:
const AWS = require("aws-sdk");
const dotenv = require("dotenv");
const jwt = require("jsonwebtoken");
const crypto = require('crypto');

dotenv.config();

const AWS_COGNITO_KEY = process.env.ACCESS_KEY_ID;
const AWS_COGNITO_SECRET = process.env.SECRET_ACCESS_KEY;
const COGNITO_REGION = process.env.COGNITO_REGION;
const USER_POOL_ID = process.env.USER_POOL_ID;
const CLIENT_ID = process.env.CLIENT_ID;
const CLIENT_SECRET= process.env.CLIENT_SECRET;

AWS.config.update({
  accessKeyId: AWS_COGNITO_KEY,
  secretAccessKey: AWS_COGNITO_SECRET,
  region: COGNITO_REGION,
});

function generateSecretHash(CLIENT_ID, CLIENT_SECRET, username) {
  const hmac = crypto.createHmac("sha256", CLIENT_SECRET);
  hmac.update(username + CLIENT_ID);
  return hmac.digest("hex");

}

module.exports.signIn = (req, res) => {
  const { username, password } = req.body;

const secretHash = generateSecretHash(CLIENT_ID, CLIENT_SECRET, username);
  console.log("clientid------------------------->",CLIENT_ID)
  console.log("Client secret----------->",CLIENT_SECRET)
  console.log("Username----->", username)
  console.log('secretHash:', secretHash);
  const params = {
    AuthFlow: "USER_PASSWORD_AUTH",
    ClientId: CLIENT_ID,
    AuthParameters: {
      USERNAME: username,
      PASSWORD: password,
      SECRET_HASH: secretHash
    },
  };
  console.log(params)
  console.log(CLIENT_ID)

cognito.initiateAuth(params, (err, data) => {
    if (err) {
      return res.status(409).json({ error: err.message });
    } else {
      const authResult = data.AuthenticationResult;
      if (authResult) {
        res.status(200).json({
          message: "User sign-in successful",
          accessToken: authResult.AccessToken,
          idToken: authResult.IdToken,
          refreshToken: authResult.RefreshToken,
        });
      } else {
        res.status(409).json({ error: "Authentication result missing" });
      }
    }
  });
};

Accepted Answer

Hi, did you encode the secret hash to Base 64 as stated in this documentation?

The following implementation works for me.

const crypto = require("crypto");

function getSecretHash(username, clientId, clientSecret) {
  return crypto
    .createHmac("sha256", clientSecret)
    .update(`${username}${clientId}`)
    .digest("base64");
}

The following implementation works for me.

```js
const crypto = require("crypto");

function getSecretHash(username, clientId, clientSecret) {
  return crypto
    .createHmac("sha256", clientSecret)
    .update(`${username}${clientId}`)
    .digest("base64");
}
```

Unable to sign-in (SecretHash does not match for the client)

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