Signature

How to generate the authorization signature

The Signature component of the Authorization header is an HMAC-SHA256 digest of the elements described below

Element	Description
Request URI	Everything after the base URL, including query parameters if present.
Timestamp	Current UNIX epoch time in milliseconds
Request body	A minified JSON-serialized string of the request body. If a body is not required (e.g. request is of type GET), use an empty string.