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| <meta charset="UTF-8"> | ||
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | ||
| <title>Deterministic CBOR with tag 42 (dCBOR42)</title> | ||
| <link rel="stylesheet" href="spec.css"><link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><rect x=%220%22 y=%220%22 width=%22100%22 height=%22100%22 fill=%22%2300ff75%22></rect></svg>"><meta name="twitter:card" content="summary_large_image"><meta name="twitter:title" property="og:title" content="DASL: Deterministic CBOR with tag 42 (dCBOR42)"><meta name="twitter:description" property="og:description" content="dCBOR42 is a form of IPLD that serializes only to deterministic CBOR, by normalizing and reducing some type flexibility. Notably, we support no ADLs."><meta name="twitter:image" property="og:image" content="https://dasl.ing/dcbor42.png"><meta name="twitter:image:alt" content="Very colourful stripes, so colourful it hurts"><meta name="twitter:url" property="og:url" content="https://dasl.ing/"><meta property="og:site_name" content="DASL"><meta property="og:locale" content="en"><meta name="theme-color" content="#00ff75"></head> | ||
| <link rel="stylesheet" href="spec.css"><link rel="icon" href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><rect x=%220%22 y=%220%22 width=%22100%22 height=%22100%22 fill=%22%2300ff75%22></rect></svg>"><meta name="twitter:card" content="summary_large_image"><meta name="twitter:title" property="og:title" content="DASL: Deterministic CBOR with tag 42 (dCBOR42)"><meta name="twitter:description" property="og:description" content="dCBOR42 is a serialization format that is deterministic (so that the same data will have the same CID) and that features native support for using CIDs as links."><meta name="twitter:image" property="og:image" content="https://dasl.ing/dcbor42.png"><meta name="twitter:image:alt" content="Very colourful stripes, so colourful it hurts"><meta name="twitter:url" property="og:url" content="https://dasl.ing/"><meta property="og:site_name" content="DASL"><meta property="og:locale" content="en"><meta name="theme-color" content="#00ff75"></head> | ||
| <body><div class="nav-back">A specification of the <a href="/">DASL Project</a>.</div><main><header><h1>Deterministic CBOR with tag 42 (dCBOR42)</h1><table><tbody><tr><th>date</th><td>2024-12-12</td></tr><tr><th>editors</th><td><a href="https://berjon.com/">Robin Berjon</a> <<a href="mailto:[email protected]">[email protected]</a>><br><a href="https://bumblefudge.com/">Juan Caballero</a> <<a href="mailto:[email protected]">[email protected]</a>></td></tr><tr><th>issues</th><td><a href="https://github.com/darobin/dasl.ing/issues">list</a>, <a href="https://github.com/darobin/dasl.ing/issues/new">new</a></td></tr><tr><th>abstract</th><td><div id="abstract"> | ||
| <p> | ||
| dCBOR42 is a form of IPLD that serializes only to deterministic CBOR, by normalizing and reducing some type | ||
| flexibility. Notably, we support no ADLs. | ||
| dCBOR42 is a serialization format that is deterministic (so that the same | ||
| data will have the same CID) and that features native support for using | ||
| CIDs as links. | ||
| </p> | ||
| </div></td></tr></tbody></table></header> | ||
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| <section> | ||
| <h2>Basics</h2> | ||
| <h2>Introduction</h2> | ||
| <p> | ||
| (See the <a href="https://datatracker.ietf.org/doc/draft-mcnally-deterministic-cbor/">current draft specification for dCBOR</a>, | ||
| and <a href="https://ftp.linux.cz/pub/internet-drafts/draft-bormann-cbor-det-01.html">Carsten Bormann's BCP document | ||
| on the underspecified determinism of Section 4.2 of the CBOR specification</a>). For debugging purposes, either | ||
| one-way conversion to DAG-JSON or <a href="https://datatracker.ietf.org/doc/draft-ietf-cbor-edn-literals/">CBOR | ||
| Extended Diagnostic Notation</a> can be used, but either way, note that the CIDs in such debugging outputs | ||
| should be the CIDs of the dCBOR42 content, not of other debugging resources. | ||
| Deterministic encodings that produce the same stream of bytes for any | ||
| given data with the same semantics are particularly useful in a content-addressed | ||
| context. dCBOR42 provides that. Additionally, it supports CBOR Tag 42 that | ||
| contains a CID ([<a href="#ref-cid" class="ref">cid</a>]). This CID can be used for content-addressed linking | ||
| between dCBOR42 documents and to raw resources. | ||
| </p> | ||
| <p> | ||
| Further details forthcoming. | ||
| dCBOR42 does not fork CBOR, CDE, or dCBOR ([<a href="#ref-cbor" class="ref">cbor</a>], [<a href="#ref-cde" class="ref">cde</a>], [<a href="#ref-dcbor" class="ref">dcbor</a>]). | ||
| Any decoder for any of those CBOR variants will be able to read dCBOR42 | ||
| content, and an encoder for those variants should be able to produce | ||
| correct dCBOR42 if configured with the right option and given | ||
| appropriately-prepared data. | ||
| </p> | ||
| </section> | ||
| <section> | ||
| <h2>Format</h2> | ||
| <p> | ||
| dCBOR42 is an application profile of dCBOR ([<a href="#ref-dcbor" class="ref">dcbor</a>]) with the following | ||
| constraints: | ||
| </p> | ||
| <ul> | ||
| <li> | ||
| Implementations must support Tag 42 (see <a href="https://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml">CBOR | ||
| Tag registry</a>). | ||
| </li> | ||
| <li> | ||
| Implementations must reject all other tags, this includes any of the tags | ||
| listed in <a href="https://tools.ietf.org/html/rfc8949#section-3.4">section | ||
| 3.4 of RFC 8949</a>. | ||
| </li> | ||
| <li> | ||
| Implementations must reject map keys that are not strings. | ||
| </li> | ||
| </ul> | ||
| <p> | ||
| All other requirements are as dCBOR ([<a href="#ref-dcbor" class="ref">dcbor</a>]). | ||
| </p> | ||
| </section> | ||
| <section> | ||
| <h2>Debugging Considerations</h2> | ||
| <p> | ||
| It is often convenient to represent dCBOR42 in textual formats for debugging | ||
| purposes, for example using JSON. | ||
| </p> | ||
| <p> | ||
| One common convention to do so is "DAG-JSON" which is a JSON expression | ||
| of the dCBOR42 data in which CIDs are represented as | ||
| <code>{ "/": "string CID" }</code>. Another option is | ||
| <a href="https://datatracker.ietf.org/doc/draft-ietf-cbor-edn-literals/">CBOR | ||
| Extended Diagnostic Notation</a>. | ||
| </p> | ||
| <p> | ||
| In any case, note that the CIDs used in such debugging outputs that may | ||
| point to <em>other</em> parts of the debugging output should be the CIDs | ||
| of the dCBOR42 content, not of the debugging resources. | ||
| </p> | ||
| </section> | ||
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| </main></body></html> | ||
| <section><h2>References</h2><dl><dt id="ref-cbor">[cbor]</dt><dd>C. Bormann. & P. Hoffman. <a href="https://www.rfc-editor.org/info/rfc8949"><cite>Concise Binary Object Representation (CBOR)</cite></a>. October 2024. URL: <a href="https://www.rfc-editor.org/info/rfc8949">https://www.rfc-editor.org/info/rfc8949</a></dd><dt id="ref-cde">[cde]</dt><dd>C. Bormann. <a href="https://datatracker.ietf.org/doc/html/draft-ietf-cbor-cde-06"><cite>CBOR Common Deterministic Encoding (CDE)</cite></a>. October 2024. URL: <a href="https://datatracker.ietf.org/doc/html/draft-ietf-cbor-cde-06">https://datatracker.ietf.org/doc/html/draft-ietf-cbor-cde-06</a></dd><dt id="ref-cid">[cid]</dt><dd>Robin Berjon & Juan Caballero. <a href="https://dasl.ing/cid.html"><cite>Content IDs (CIDs)</cite></a>. 2024-12-12. URL: <a href="https://dasl.ing/cid.html">https://dasl.ing/cid.html</a></dd><dt id="ref-dcbor">[dcbor]</dt><dd>W. McNally, C. Allen, C. Bormann, & L. Lundblade. <a href="https://datatracker.ietf.org/doc/draft-mcnally-deterministic-cbor/"><cite>dCBOR: A Deterministic CBOR Application Profile</cite></a>. October 2024. URL: <a href="https://datatracker.ietf.org/doc/draft-mcnally-deterministic-cbor/">https://datatracker.ietf.org/doc/draft-mcnally-deterministic-cbor/</a></dd></dl></section></main></body></html> | ||
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