Cryptographic Hyperlinks
draft-sporny-hashlink-06
Network Working Group M. Sporny
Internet-Draft Digital Bazaar
Intended status: Standards Track L. Rosenthol
Expires: May 4, 2021 Adobe Systems
October 31, 2020
Cryptographic Hyperlinks
draft-sporny-hashlink-06
Abstract
When using a hyperlink to fetch a resource from the Internet, it is
often useful to know if the resource has changed since the data was
published. Cryptographic hashes, such as SHA-256, are often used to
determine if published data has changed in unexpected ways. Due to
the nature of most hyperlinks, the cryptographic hash is often
published separately from the link itself. This specification
describes a data model and serialization formats for expressing
cryptographically protected hyperlinks. The mechanisms described in
the document enables a system to publish a hyperlink in a way that
empowers a consuming application to determine if the resource
associated with the hyperlink has changed in unexpected ways.
Feedback
This specification is a work product of the W3C Digital Verification
Community Group [1] and the W3C Credentials Community Group [2].
Feedback related to this specification should be logged in the issue
tracker [3] or be sent to public-credentials@w3.org [4].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 4, 2021.
Sporny & Rosenthol Expires May 4, 2021 [Page 1]
Internet-Draft Cryptographic Hyperlinks October 2020
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
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This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Multiple Encodings . . . . . . . . . . . . . . . . . . . 4
2. Hashlink Data Model . . . . . . . . . . . . . . . . . . . . . 4
2.1. The Resource Hash . . . . . . . . . . . . . . . . . . . . 4
2.2. The Optional Metadata . . . . . . . . . . . . . . . . . . 4
2.2.1. URLs . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2.2. Content Type . . . . . . . . . . . . . . . . . . . . 4
2.2.3. Experimental Metadata . . . . . . . . . . . . . . . . 5
3. Hashlink Serialization . . . . . . . . . . . . . . . . . . . 5
3.1. Hashlink URL . . . . . . . . . . . . . . . . . . . . . . 5
3.1.1. Serializing the Resource Hash . . . . . . . . . . . . 5
3.1.2. Serializing the Metadata . . . . . . . . . . . . . . 6
3.1.3. Deserializing the Metadata . . . . . . . . . . . . . 6
3.1.4. A Simple Hashlink Example . . . . . . . . . . . . . . 7
3.2. Hashlink as a Parameterized URL . . . . . . . . . . . . . 7
3.2.1. Hashlink as a Parameterized URL Example . . . . . . . 8
4. Hashlink Encoders and Decoders . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5.1. Insecure Hashing Functions . . . . . . . . . . . . . . . 8
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. Normative References . . . . . . . . . . . . . . . . . . 8
6.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Security Considerations . . . . . . . . . . . . . . 9
Appendix B. Test Values . . . . . . . . . . . . . . . . . . . . 9
B.1. Simple Hashlink URL . . . . . . . . . . . . . . . . . . . 9
B.2. Multi-sourced Hashlink URL . . . . . . . . . . . . . . . 10
Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Uniform Resource Locators (URLs) enable software developers to build
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