signer.js

// Implements the signing example w/out AWS SDK in nodejs. See:
// http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-streaming.html
const crypto = require('crypto');

function signingKey(secretAccessKey, region, service, datetime) {
  var date = datetime.substr(0, 8);
  var kDate = crypto.createHmac('sha256', 'AWS4' + secretAccessKey).update(date).digest();
  var kRegion = crypto.createHmac('sha256', kDate).update(region).digest();
  var kService = crypto.createHmac('sha256', kRegion).update(service).digest();
  return crypto.createHmac('sha256', kService).update('aws4_request').digest('hex');
}

var kSigning = signingKey('wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY','us-east-1','s3','20130524T000000Z');
console.log(kSigning);

var stringToSign="AWS4-HMAC-SHA256\n20130524T000000Z\n20130524/us-east-1/s3/aws4_request\ncee3fed04b70f867d036f722359b0b1f2f0e5dc0efadbc082b76c4c60e316455"
var signature = crypto.createHmac('sha256', new Buffer(kSigning,'hex')).update(stringToSign).digest('hex');
console.log(signature);

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