NodeJS example code to generate a RFC 2104 compliant HMAC

core.js

var crypto = require("crypto");
/**
 * Get the signature/digest of a supplied input string
 * @param data [Required] The String to encode
 * @param awsSecretKey [Required] Secret key shared with Amazon
 * @param algorithm [Optional] Encryption algorithm, defaults to sha256
 * @param encoding [Optional] The output encoding. Default to base64
 * @returns Str with encoded digest of the input string
 */
function generateHmac (data, awsSecretKey, algorithm, encoding) {
  encoding = encoding || "base64";
  algorithm = algorithm || "sha256";
  return crypto.createHmac(algorithm, awsSecretKey).update(data).digest(encoding);
}
var d = new Date();
var rfc2104Hmac = generateHmac(d.toUTCString(), "awsSecretKey value");
 
console.log(rfc2104Hmac);

example.js

var request = require("request");
var crypto = require("crypto");
var d = new Date().toUTCString();
var config = {
  awsAccessKeyId : "AWS key",
  awsSecretKey   : "AWS Secret"
}

// Options for the http POST request
var options = {
  "headers" : {
    "Date"   : d, // Must pass the Date header as well as the X-Amzn-Authorization header
    "X-Amzn-Authorization" : "AWS3-HTTPS AWSAccessKeyId=" + config.awsAccessKeyId +
      ",Algorithm=HMACSHA256,Signature=" + generateHmac(d, config.awsSecretKey)
  },
  "form"    : {
  }
};


function generateHmac (data, awsSecretKey, algorithm, encoding) {
  encoding = encoding || "base64";
  algorithm = algorithm || "sha256";
  return crypto.createHmac(algorithm, awsSecretKey).update(data).digest(encoding);
}


request.post(
  "https://email.us-east-1.amazonaws.com/",
  options,
  function (error, response, body) {
    console.log(response.statusCode, body);
  }
);

When I run example.js I get an error:

403 '<AccessDeniedException>\n  <Message>Unable to determine service/operation name to be authorized</Message>\n</AccessDeniedException>\n'

I did replace the id and key with my own. Any ideas?

Post your code but that's an IAM Access error - You're using a key that doesn't have permission to the ARN or the service itself

I have spent hours looking for this answer thank you for posting this.

Bro, Love from India. Cheers!

Does the above code work in React-native?