in lib/aws-signature-v4.js [79:91]
exports.createSignature = function (
secret,
time,
region,
service,
stringToSign
) {
var h1 = hmac("AWS4" + secret, toDate(time)); // date-key
var h2 = hmac(h1, region); // region-key
var h3 = hmac(h2, service); // service-key
var h4 = hmac(h3, "aws4_request"); // signing-key
return hmac(h4, stringToSign, "hex");
};