# v15 of the HTTP message signature protocol

This section of the concept documentation describes technical details of Upvest's implementation of v15 of the HTTP message signature protocol.

- [Content Digest](/products/tol/concepts/api_concepts/http_signatures/v15/v15_content_digest)
- [Signature Components](/products/tol/concepts/api_concepts/http_signatures/v15/v15_signature_components)
- [Calculation of the Signature](/products/tol/concepts/api_concepts/http_signatures/v15/v15_calculation_of_the_signature)
- [Supported Signing Algorithms](/products/tol/concepts/api_concepts/http_signatures/http_signature_signing_alogrithms)
- [Base64 encoding](/products/tol/concepts/api_concepts/http_signatures/http_signature_base64_encoding)