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# filecoin-project / specs

The Filecoin protocol specification

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## Latest commit

Adds spec for the Poseidon hash function to the crypto primitives section.
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# Filecoin Specification

This is the Filecoin Specification, a repository that contains documents, code, models, and diagrams that constitute the specification of the Filecoin Protocol. This repository is the singular source of truth for the Filecoin Protocol. All implementations of the Filecoin Protocol should match and comply with the descriptions, interfaces, code, and models defined in this specification.

https://spec.filecoin.io is the user-friendly website rendering, which we recommend for reading this repository. The website is updated automatically with every merge to master.

## Install

To build the spec website you need

On macOS you can get node from Homebrew

brew install node

Clone the repo, and use npm install to fetch the dependencies

git clone https://github.com/filecoin-project/specs.git
npm install

To run the development server with live-reload locally, run:

npm start

Then open http://localhost:1313 in the browser

## Writing the spec

The spec is written in markdown. Each section is markdown document in the content directory. The first level of the directory structure denotes the top level sections of the spec; (Introduction, Systems, etc.) The _index.md file in each folder is used as the starting point for each section. For example the Introduction starts in content/intro/_index.md.

Sections can be split out into multiple markdown documents. The build process combines them into a single html page. The sections are ordered by the weight front-matter property. The introduction appears at the start of the html page because content/intro/_index.md has weight: 1, while content/systems/_index.html has weight: 2 so it appears as the second section.

You can split out sub-sections by adding additional pages to a section directory. The content/intro/concepts.md defines the Key Concepts sub-section of the the Introduction. The order of sub-sections within a section is again controlled by setting the weight property. This pattern repeats for sub sub folders which represent sub sub sections.

The markdown documents should all be well formed, with a single h1, and headings should increment by a single level.

Note: Regular markdown files like content/intro/concepts.md can't reference resources such as images, or other files. Such resources can be referenced only from _index.md files. Given that a folder will have an _index.md file already, there is the following work around to reference resources from any file: create a new sub-folder in the same folder where the initial .md file was, e.g., content/intro/concepts/_index.md, include the content from concepts.md in the _index.md file, add the resource files (for example, images) in the new folder and reference the resource file from the new _index.md file inside the concepts folder. The referencing syntax and everything else works the same way.

Use npm test to run a markdown linter and prettier to check for common errors. It runs in CI and you can run it locally with:

npm test
content/algorithms/crypto/randomness.md
15:39-15:46  warning  Found reference to undefined definition  no-undefined-references  remark-lint
54:24-54:31  warning  Found reference to undefined definition  no-undefined-references  remark-lint

⚠ 2 warnings

Format errors can be fixed by running npm run format.

Checking formatting...
[warn] content/systems/filecoin_token/block_reward_minting.md
[warn] Code style issues found in the above file(s). Forgot to run Prettier?

## Page Template

A spec document should start with a YAML front-matter section and contain at least a single h1, as below.

---
title: Important thing
weight: 1
dashboardState: wip
dashboardAudit: missing
---

# Important thing

## Code

Wrap code blocks in code fences. Code fences should always have a lang. It is used to provide syntax highlighting. Use text as the language flag for pseudocode for no highlighting.

text



You can embed source code from local files or external other repos using the embed shortcode.

{{<embed src="/path/to/local/file/types.go"  lang="go" symbol="Channel">}}

{{<embed src="https://github.com/filecoin-project/lotus/blob/master/build/bootstrap.go" lang="go">}}


## Images

Use normal markdown syntax to include images.

For dot and mermaid diagrams you link to the source file and the pipelines will handle converting that to svg.

# relative to the markdown file

![Alt text](picture.jpg)

# relative to the content folder

![Alt text](/content/intro/diagram1.mmd)

![Alt text](graph.dot 'Graph title')

The alt text is used as the title if not provided.

Use markdown syntax [text](markdown-document-name).

These links use "portable links" just like relref. Just give it the name of the file and it will fetch the correct relative path and title automatically. You can override the title by passing a second string in the link definition.

Note: When using anchors the title can't be fetched automatically.

[](storage_power_consensus)

# Renders to

<a href="/systems/filecoin_blockchain/storage_power_consensus" title="Storage Power Consensus">Storage Power Consensus</a>

[Storage Power](storage_power_consensus 'Title to override the page original title')

# Renders to

<a href="/systems/filecoin_blockchain/storage_power_consensus" title="Title to override the page original title">Storage Power</a>

[Tickets](storage_power_consensus#the-ticket-chain-and-drawing-randomness 'The Ticket chain and drawing randomness')

# Renders to

<a href="/systems/filecoin_blockchain/storage_power_consensus#the-ticket-chain-and-drawing-randomness" title="The Ticket chain and drawing randomness">Tickets</a>

## Shortcodes

### embed

# src relative to the page

{{<embed src="piece_store.go" lang="go">}}

# src relative to content folder

{{<embed src="/systems/piece_store.go" lang="go">}}

# can just embed a markdown file

{{<embed src="section.md" markdown="true">}}

# can embed symbols from Go files

# extracts comments and symbol body

{{<embed src="types.go"  lang="go" symbol="Channel">}}

# can embed from external sources like github

{{<embed src="https://github.com/filecoin-project/lotus/blob/master/build/bootstrap.go" lang="go">}}

This shortcode also supports the property title to add a permalink below the embed.

### listing

The listing shortcode creates tables from externals sources, supports Go struct.

# src relative to the page

{{<listing src="piece_store.go" symbol="Channel">}}

# src relative to content folder

{{<listing src="/systems/piece_store.go" symbol="Channel">}}

# src can also be from the externals repos

{{<listing src="/externals/go-data-transfer/types.go"  symbol="Channel">}}

### mermaid

Inline mermaid syntax rendering

{{< mermaid >}}
graph TD
A[Christmas] -->|Get money| B(Go shopping)
B --> C{Let me think}
C -->|One| D[Laptop]
C -->|Two| E[iPhone]
C -->|Three| F[fa:fa-car Car]

{{</ mermaid >}}

### hint

<!-- info|warning|danger -->

{{< hint info >}}
**Markdown content**
Lorem markdownum insigne. Olympo signis Delphis! Retexi Nereius nova develat
stringit, frustra Saturnius uteroque inter! Oculis non ritibus Telethusa
{{< /hint >}}

### katex

We should only use inline mode for now! Display mode has a bug and is not responsive the formulas don't break in small screen. Track: https://github.com/KaTeX/KaTeX/issues/2271

<!-- Use $math$ for inline mode-->

{{<katex>}}
$SectorInitialConsensusPledge = \\[0.2cm] 30\% \times FILCirculatingSupply \times \frac{SectorQAP}{max(NetworkBaseline, NetworkQAP)}$
{{</katex >}}

<!-- Use $$math$$ for display mode-->

{{<katex>}}
$$SectorInitialConsensusPledge = \\[0.2cm] 30\% \times FILCirculatingSupply \times \frac{SectorQAP}{max(NetworkBaseline, NetworkQAP)}$$
{{</katex >}}

## Math mode

For short snippets of math text (e.g., inline reference to parameters, or single formulas) it is easier to use the {{<katex>}}/{{/katex}} shortcode (as described just above). Check how KaTeX parses math typesetting here.

For extensive blocks of math content it is more convenient to use math-mode to avoid having to repeat the katex shortcode for every math formula.

Check this example example

Some syntax like \_ can't go through HUGO markdown parser and for that reason we need to wrap math text with code blocks, code fendes or the shortcode {{<plain>}}. See examples below.

### Add math-mode prop to the Frontmatter

---
title: Math Mode
math-mode: true
---

### Wrap def, gdef, etc.

Math text needs to be wrapped to avoid Hugo's Markdown parser. When wrapping defs or any math block that doesn't need to be rendered the recommended option is to use the shortcode {{<plain hidden}} with the hidden argument.

{{<plain hidden>}}

$$\gdef\createporepbatch{\textsf{create_porep_batch}} \gdef\GrothProof{\textsf{Groth16Proof}} \gdef\Groth{\textsf{Groth16}} \gdef\GrothEvaluationKey{\textsf{Groth16EvaluationKey}} \gdef\GrothVerificationKey{\textsf{Groth16VerificationKey}} {{</plain>}}$$

### Wrap inline math text with code blocks

The index of a node in a $\BinTree$ layer $l$. The leftmost node in a tree has $\index_l = 0$.

### Wrap math blocks with code fences

text
$\overline{\underline{\Function \BinTree\dot\createproof(c: \NodeIndex) \rightarrow \BinTreeProof_c}}$
$\line{1}{\bi}{\leaf: \Safe = \BinTree\dot\leaves[c]}$
$\line{2}{\bi}{\root: \Safe = \BinTree\dot\root}$

$\line{3}{\bi}{\path: \BinPathElement^{[\BinTreeDepth]}= [\ ]}$
$\line{4}{\bi}{\for l \in [\BinTreeDepth]:}$
$\line{5}{\bi}{\quad \index_l: [\len(\BinTree\dot\layer_l)] = c \gg l}$
$\line{6}{\bi}{\quad \missing: \Bit = \index_l \AND 1}$
$\line{7}{\bi}{\quad \sibling: \Safe = \if \missing = 0:}$
$\quad\quad\quad \BinTree\dot\layer_l[\index_l + 1]$
$\quad\quad\thin \else:$
$\quad\quad\quad \BinTree\dot\layer_l[\index_l - 1]$
$\line{8}{\bi}{\quad \path\dot\push(\BinPathElement \thin \{\ \sibling, \thin \missing\ \} \thin )}$

$\line{9}{\bi}{\return \BinTreeProof_c \thin \{\ \leaf, \thin \root, \thin \path\ \}}$


## Front-matter

Description for all the available frontmatter properties

# Page Title to be used in the navigation
title: Libraries
# Small description for html metadata, if not present the first couple of paragraphs will be used instead
description: Libraries used from Filecoin
# This will be used to order the ToC, navigation and any other listings of pages
weight: 3
# This will make a page section collapse in the navigation
bookCollapseSection: true
# This will hidden the page from the navigation
bookhidden: true
# This is used in the dashboard to describe the importance of the page content
dashboardWeight: 2
# This is used in the dashboard to describe the state of the page content options are "missing", "incorrect", "wip", "reliable", "stable" or "n/a"
dashboardState: stable
# This is used in the dashboard to describe if the theory of the page has been audited, options are "missing", "wip", "done" or "n/a"
dashboardAudit: wip
# When dashboardAudit is stable we should have a report url
dashboardAuditURL: https://url.to.the.report
# The date that the report at dashboardAuditURL was completed
dashboardAuditDate: '2020-08-01'
# This is used in the dashboard to describe if the page content has compliance tests, options are 0 or numbers of tests
dashboardTests: 0

## References

The Filecoin protocol specification