Add docs

docs/README.md

@@ -1,6 +1,7 @@
 # doip.js
 
-doip.js allows browsers and Node.js projects to verify decentralized online identities based on OpenPGP.
+doip.js allows websites and Node.js projects to verify decentralized online
+identities based on OpenPGP.
 
 ## Features
 
@@ -14,16 +15,27 @@ doip.js allows browsers and Node.js projects to verify decentralized online iden
 
 ## About Keyoxide
 
-[Keyoxide](https://keyoxide.org/), made by Yarmo Mackenbach, is a modern, secure and privacy-friendly platform to establish decentralized online identities using a novel concept know as [DOIP](doip.md). In an effort to make this technology accessible for other projects and stimulate the emergence of both complementary and competing projects, this project-agnostic library is [published on codeberg.org](https://codeberg.org/keyoxide/doipjs) and open sourced under the [Apache-2.0](https://codeberg.org/keyoxide/doipjs/src/branch/main/LICENSE) license.
+[Keyoxide](https://keyoxide.org/), made by Yarmo Mackenbach, is a modern, secure
+and privacy-friendly platform to establish decentralized online identities using
+a novel concept know as [DOIP](doip.md). In an effort to make this technology
+accessible for other projects and stimulate the emergence of both complementary
+and competing projects, this project-agnostic library is
+[published on codeberg.org](https://codeberg.org/keyoxide/doipjs) and open
+sourced under the
+[Apache-2.0](https://codeberg.org/keyoxide/doipjs/src/branch/main/LICENSE)
+license.
 
 ## Community
 
-There's a [Keyoxide Matrix room](https://matrix.to/#/#keyoxide:matrix.org) where we discuss everything DOIP and Keyoxide.
+There's a [Keyoxide Matrix room](https://matrix.to/#/#keyoxide:matrix.org) where
+we discuss everything DOIP and Keyoxide.
 
 ## Donate
 
-Please consider [donating](https://liberapay.com/Keyoxide/) if you think this project is a step in the right direction for the internet.
+Please consider [donating](https://liberapay.com/Keyoxide/) if you think this
+project is a step in the right direction for the internet.
 
 ## Funding
 
-This library was realized with funding from [NLnet](https://nlnet.nl/project/Keyoxide/).
+This library was realized with funding from
+[NLnet](https://nlnet.nl/project/Keyoxide/).

docs/_sidebar.md

@@ -1,6 +1,8 @@
 - Getting started
-  - [Quick start](quickstart.md)
+  - [Installation](installation.md)
-  - [Configuration](configuration.md)
+  - [Quick start (Node.js)](quickstart-nodejs.md)
+  - [Quick start (browser)](quickstart-browser.md)
+  - [Terminology](terminology.md)
 
 - Reference
   - [API](api.md)
@@ -8,13 +10,25 @@
 
 - Concepts
   - [DOIP](doip.md)
-  - [Cryptographic keys](cryptographickeys.md)
   - [Proofs](proofs.md)
   - [Claims](claims.md)
-  - [Service providers](serviceproviders,md)
+  - [Service providers](serviceproviders.md)
 
 - Service providers
-  - [Liberapay](serviceproviders/liberapay.md)
+  - [dev.to](serviceproviders/devto.md)
+  - [discourse](serviceproviders/discourse.md)
+  - [dns](serviceproviders/dns.md)
+  - [fediverse](serviceproviders/fediverse.md)
+  - [gitea](serviceproviders/gitea.md)
+  - [github](serviceproviders/github.md)
+  - [gitlab](serviceproviders/gitlab.md)
+  - [hackernews](serviceproviders/hackernews.md)
+  - [liberapay](serviceproviders/liberapay.md)
+  - [lobste.rs](serviceproviders/lobsters.md)
+  - [mastodon](serviceproviders/mastodon.md)
+  - [reddit](serviceproviders/reddit.md)
+  - [twitter](serviceproviders/twitter.md)
+  - [xmpp](serviceproviders/xmpp.md)
 
 - More
   - [Changelog](changelog.md)

docs/claims.md

@@ -8,6 +8,15 @@ identity, the other being a [proof](proofs.md).
 A claim is always a phrase, string or URI that is expected to be found inside
 the proof. **The presence of a claim inside a proof verifies that claim.**
 
+## Claims in OpenPGP keys
+
+DOIP assumes claims are stored in OpenPGP keys as so-called notations. The
+format for all claims is the same:
+
+```
+proof@metacode.biz=...
+```
+
 ## Relation with proof
 
 The relation between proof and claim is defined by three variables: `format`,

docs/configuration.md

@@ -1 +0,0 @@
-# Configuration

docs/cryptographickeys.md

@@ -1 +0,0 @@
-# Cryptographic keys

docs/doip.md

@@ -1 +1,81 @@
 # Decentralized OpenPGP Identity Proofs
+
+Decentralized OpenPGP Identity Proofs, or DOIPs, are a way of identifying
+and linking profiles and accounts on the internet. Take ten different websites
+and make an account on each of them. How could outsiders tell they were created
+by the same person? They can't directly. You could be **Alice** on website A but
+**Alice123** on website B.
+
+What if a bad actor creates an account **Alice** on a brand new website and
+starts contacting people you know from website A? How could they verify this new
+accounts is in fact you?
+
+With the digital realm becoming more and more a second home in our lives, we
+need tools to identify ourselves and stay safe.
+
+## Why decentralized?
+
+Say you have a Facebook or Google account. You can use that to create accounts
+on different websites. Problem solved! That is, until the day you get an email
+that your account was flagged by AI, you just lost access to all those websites
+and there's no way to contact them to restore it.
+
+This [happens way too often](https://www.businessinsider.com/google-users-locked-out-after-years-2020-10?international=true&r=US&IR=T).
+
+Why does it happen? You are a number to them. Losing you as a user doesn't cost
+them anything.
+
+Therefore, it is imperative that new solutions give the people **sovereignty**
+over their identity. How do we do this? By making new solutions
+**decentralized**.
+
+**Decentralized** simply means that there is no central authority. In the
+classic model, you give your data to Facebook or Google and the truth is what
+they say it is: if they say you no longer exist, then, well, you no longer
+exist. In the **decentralized** model, you hold your own data and no one can
+take that away from you. This also means that service providers should fight for
+you to keep you as a user since **you allow them to use your data**. Any misstep
+on their behalf and you can take it away.
+
+## Why OpenPGP?
+
+To achieve user sovereignty, DOIP relies on **OpenPGP** cryptographic keys. Read
+more about those keys [here](cryptographickeys.md) but in short: they are like
+documents that the whole world can read but only you can edit. In that way, you
+can publish a list of profiles on websites that you have created but no one can
+do that for you in an attempt to impersonate you.
+
+## Bidirectional linking
+
+There's a catch: simply adding a link to a profile inside your OpenPGP document
+is not sufficient. If it were, you could claim any profile anywhere simply by
+linking to them!
+
+This is why DOIP uses two-way or bidirectional linking. Your key must link to a
+profile and your profile must link back to the key. That is the only way to make
+sure you hold both the key and the profile.
+
+This also solves the imposter problem. A bad actor could you link to your
+profile but since your profile doesn't link back to their key, DOIP will not
+verify their claim. Unless they hacked your profile, in which case you have more
+urgent problems.
+
+How does a profile link to a cryptographic key? Every key can be uniquely
+identified using what we call their **fingerprint**. All a profile page needs to
+do is contain that fingerprint somehow. Usually, this can be added as the last
+line to a biography.
+
+Note that the service provider itself needs to do a few things to support the
+verification of DOIPs. Please refer to the [list of supported service providers](serviceproviders.md)
+
+## Adding more than one proof
+
+The endgame of using DOIP is to add at least two profile. Proving that you own
+a single profile—in a way—doesn't prove anything. The issue is that
+we cannot prove that **you**, the physical being **you**, holds that key. DOIP
+can only verify that "*whoever holds that key also holds that profile*".
+
+By adding at least two profiles, you can create meaningful links between those
+profiles. If someone knows **you**, the physical being **you**, is **Alice** on
+website A, they will also now know that you are **Alice123** on website B,
+simply because "*whoever holds that key also holds both of those profiles*".

docs/installation.md

@@ -0,0 +1,21 @@
+# Installation
+
+Install using **yarn**:
+
+```bash
+yarn add doipjs
+```
+
+Install using **NPM**:
+
+```bash
+npm install --save doipjs
+```
+
+Install on website by including the following HTML snippet:
+
+```html
+<script src="https://cdn.jsdelivr.net/npm/keyoxide@0.3.0/dist/doip.min.js"></script>
+```
+
+Next step: [quick start (Node.js)](quickstart-nodejs.md) and [quick start (browser)](quickstart-browser.md)

docs/quickstart-browser.md

@@ -0,0 +1,14 @@
+# Quick start (browser)
+
+Basic example:
+
+```javascript
+const verifyIdentity = async (url, fp) => {
+  console.log(await doip.verify(url, fp))
+}
+verifyIdentity('dns:doip.rocks', '9f0048ac0b23301e1f77e994909f6bd6f80f485d')
+```
+
+This snippet works en will verify the [doip.rocks](https://doip.rocks) domain as
+linked to Yarmo's cryptographic key using the [dns](serviceproviders/dns.md)
+service provider.

docs/quickstart-nodejs.md

@@ -0,0 +1,16 @@
+# Quick start (Node.js)
+
+Basic example:
+
+```javascript
+const doip = require('doip')
+
+const verifyIdentity = async (url, fp) => {
+  console.log(await doip.verify(url, fp))
+}
+verifyIdentity('dns:doip.rocks', '9f0048ac0b23301e1f77e994909f6bd6f80f485d')
+```
+
+This snippet works en will verify the [doip.rocks](https://doip.rocks) domain as
+linked to Yarmo's cryptographic key using the [dns](serviceproviders/dns.md)
+service provider.

docs/quickstart.md

@@ -1,47 +0,0 @@
-# Quick start
-
-## Installation
-
-Install using **yarn**:
-
-```bash
-yarn add doipjs
-```
-
-Install using **NPM**:
-
-```bash
-npm install --save doipjs
-```
-
-## Usage (Node.js)
-
-Basic example:
-
-```javascript
-const doip = require('doip')
-
-const verifyIdentity = async (url, fp) => {
-  console.log(await doip.verify(url, fp))
-}
-verifyIdentity('dns:doip.rocks', '9f0048ac0b23301e1f77e994909f6bd6f80f485d')
-```
-
-This snippet works en will verify the [doip.rocks](https://doip.rocks) domain as
-linked to Yarmo's cryptographic key using the [dns](serviceproviders/dns.md)
-service provider.
-
-## Usage (browser)
-
-The same code as above, but for the browser:
-
-```html
-<script src="https://cdn.jsdelivr.net/npm/keyoxide@0.3.0/dist/doip.min.js"></script>
-```
-
-```javascript
-const verifyIdentity = async (url, fp) => {
-  console.log(await doip.verify(url, fp))
-}
-verifyIdentity('dns:doip.rocks', '9f0048ac0b23301e1f77e994909f6bd6f80f485d')
-```

docs/serviceproviders.md

@@ -1 +1,18 @@
 # Service providers
+
+Currently, the following service providers are supported:
+
+- dev.to ([documentation](serviceproviders/devto.md) - [official website](https://dev.to/))
+- discourse ([documentation](serviceproviders/discourse.md) - [official website](https://www.discourse.org/))
+- dns ([documentation](serviceproviders/dns.md))
+- fediverse ([documentation](serviceproviders/fediverse.md))
+- gitea ([documentation](serviceproviders/gitea.md) - [official website](https://gitea.io/))
+- github ([documentation](serviceproviders/github.md) - [official website](https://github.com/))
+- gitlab ([documentation](serviceproviders/gitlab.md) - [official website](https://about.gitlab.com/))
+- hackernews ([documentation](serviceproviders/hackernews.md) - [official website](https://news.ycombinator.com/))
+- liberapay ([documentation](serviceproviders/liberapay.md) - [official website](https://liberapay.com/))
+- lobste.rs ([documentation](serviceproviders/lobsters.md) - [official website](https://lobste.rs/))
+- mastodon ([documentation](serviceproviders/mastodon.md) - [official website](https://joinmastodon.org/))
+- reddit ([documentation](serviceproviders/reddit.md) - [official website](https://www.reddit.com/))
+- twitter ([documentation](serviceproviders/twitter.md) - [official website](https://twitter.com/home))
+- xmpp ([documentation](serviceproviders/xmpp.md) - [official website](https://xmpp.org/))

docs/serviceproviders/devto.md

@@ -0,0 +1,21 @@
+# dev.to
+
+## Proof
+
+Proofs are defined as posts and should contain the following information:
+
+```
+This is an OpenPGP proof that connects [my OpenPGP key](https://keyoxide.org/FINGERPRINT) to [this dev.to account](https://dev.to/USERNAME). For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT` and `USERNAME`.
+
+## Claim
+
+```
+https://dev.to/USERNAME/POST_TITLE
+```
+
+Make sure to replace `USERNAME` and `POST_TITLE`.

docs/serviceproviders/discourse.md

@@ -0,0 +1,21 @@
+# discourse
+
+## Proof
+
+Proofs are defined by including the following information in the **About me**:
+
+```
+This is an OpenPGP proof that connects my OpenPGP key to this Discourse account. For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://DOMAIN/u/USERNAME
+```
+
+Make sure to replace `DOMAIN` and `USERNAME`.

docs/serviceproviders/dns.md

@@ -0,0 +1,19 @@
+# dns
+
+## Proof
+
+Proofs are defined by adding a **TXT** record to the DNS records:
+
+```
+openpgp4fpr:FINGERPRINT
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+dns:DOMAIN
+```
+
+Make sure to replace `DOMAIN`.

docs/serviceproviders/fediverse.md

@@ -0,0 +1,22 @@
+# fediverse
+
+Fediverse refers to the network of ActivityPub-compatible servers.
+
+## Proof
+
+Proofs are defined by adding the following information to the **Bio** or
+similar field:
+
+```
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://DOMAIN/users/USERNAME
+```
+
+Make sure to replace `DOMAIN` and `USERNAME`.

docs/serviceproviders/gitea.md

@@ -0,0 +1,20 @@
+# gitea
+
+## Proof
+
+Proofs are defined by creating a public repository `gitea_proof` and setting the
+description to:
+
+```
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://DOMAIN/USERNAME/gitea_proof
+```
+
+Make sure to replace `DOMAIN` and `USERNAME`.

docs/serviceproviders/github.md

@@ -0,0 +1,22 @@
+# github
+
+## Proof
+
+Proofs are defined by creating a public gist and a file `openpgp.md` with the
+following information:
+
+```
+This is an OpenPGP proof that connects [my OpenPGP key](https://keyoxide.org/FINGERPRINT) to [this Github account](https://github.com/USERNAME). For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT` and `USERNAME`.
+
+## Claim
+
+```
+https://gist.github.com/USERNAME/GIST_ID
+```
+
+Make sure to replace `USERNAME` and `GIST_ID`.

docs/serviceproviders/gitlab.md

@@ -0,0 +1,20 @@
+# gitlab
+
+## Proof
+
+Proofs are defined by creating a public project with slug `gitea_proof` and
+setting the description to:
+
+```
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://DOMAIN/USERNAME/gitlab_proof
+```
+
+Make sure to replace `DOMAIN` and `USERNAME`.

docs/serviceproviders/hackernews.md

@@ -0,0 +1,21 @@
+# hackernews
+
+## Proof
+
+Proofs are defined by adding the following information to the **about**:
+
+```
+This is an OpenPGP proof that connects my OpenPGP key to this Hackernews account. For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://news.ycombinator.com/user?id=USERNAME
+```
+
+Make sure to replace `USERNAME`.

docs/serviceproviders/liberapay.md

@@ -1 +1,19 @@
-# Liberapay
+# liberapay
+
+## Proof
+
+Proofs are defined by adding the following information to a **Statement**:
+
+```
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://liberapay.com/USERNAME
+```
+
+Make sure to replace `USERNAME`.

docs/serviceproviders/lobsters.md

@@ -0,0 +1,21 @@
+# lobste.rs
+
+## Proof
+
+Proofs are defined by adding the following information to the **About**:
+
+```
+This is an OpenPGP proof that connects my OpenPGP key to this Lobste.rs account. For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://lobste.rs/u/USERNAME
+```
+
+Make sure to replace `USERNAME`.

docs/serviceproviders/mastodon.md

@@ -0,0 +1,14 @@
+# mastodon
+
+## Proof
+
+Proofs are defined by adding an item under `Profile metadata` with `OpenPGP` as
+label and the fingerprint as value.
+
+## Claim
+
+```
+https://DOMAIN/@USERNAME
+```
+
+Make sure to replace `DOMAIN` and `USERNAME`.

docs/serviceproviders/reddit.md

@@ -0,0 +1,21 @@
+# reddit
+
+## Proof
+
+Proofs are defined as posts and should contain the following information:
+
+```
+This is an OpenPGP proof that connects my OpenPGP key to this Reddit account. For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://reddit.com/user/USERNAME/comments/POST_ID/POST_TITLE
+```
+
+Make sure to replace `USERNAME`, `POST_ID` and `POST_TITLE`.

docs/serviceproviders/twitter.md

@@ -0,0 +1,21 @@
+# twitter
+
+## Proof
+
+Proofs are defined as tweets and should contain the following information:
+
+```
+This is an OpenPGP proof that connects my OpenPGP key to this Twitter account. For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+https://twitter.com/USERNAME/status/TWEET_ID
+```
+
+Make sure to replace `USERNAME` and `TWEET_ID`.

docs/serviceproviders/xmpp.md

@@ -0,0 +1,29 @@
+# xmpp
+
+## Proof
+
+Proofs are defined by adding the following information to the **About** section
+of the profile's vCard information using a client that support editing that
+information:
+
+```
+This is an OpenPGP proof that connects my OpenPGP key to this XMPP account. For details check out https://keyoxide.org/guides/openpgp-proofs
+
+[Verifying my OpenPGP key: openpgp4fpr:FINGERPRINT]
+```
+
+Make sure to replace `FINGERPRINT`.
+
+## Claim
+
+```
+xmpp:XMPP_ID
+```
+
+or with OMEMO:
+
+```
+xmpp:XMPP_ID?omemo-sid-OMEMO_DEVICE_ID=OMEMO_FINGERPRINT&...
+```
+
+Make sure to replace `XMPP_ID`, `OMEMO_DEVICE_ID` and `OMEMO_FINGERPRINT`.

docs/terminology.md

@@ -0,0 +1,129 @@
+# Terminology
+
+## Claim
+
+A piece of data that is expected to be contained with the [proof](#proof). When
+found, the claim—and the identity associated with the claim—is
+verified. Within the context of this project, a claim is always the fingerprint
+of an [OpenPGP](#openpgp) [cryptographic key](#cryptographic-key), but formatted
+in different ways depending on the [service provider](#service-provider).
+
+For more detailed information, please refer to [Claims](claims.md).
+
+## Cryptographic key
+
+
+According to [Wikipedia](https://en.wikipedia.org/wiki/Key_(cryptography)):
+
+> [...] a piece of information (a parameter) that determines the functional
+output of a cryptographic algorithm.
+
+Cryptographic keys can be used to encrypt/decrypt data and verify digital
+signatures.
+
+Within the context of this project, we can view cryptographic keys as documents
+that everyone can read but only one person can edit. This makes it the perfect
+candidate to serve as vessel for [decentralized](#decentralized)
+[identity](#identity) [claims](#claim).
+
+## Decentralized
+
+A model for interaction between computers or nodes in a network. Its
+distinguishing feature is that this model does not rely on a central authority,
+unlike traditional centralized models that are used by Facebook, Google and all
+other privacy-invading corporations.
+
+A core outcome of choosing a decentralized model is that it gives the user
+**sovereignty** over their data, instead of giving all the power to the central
+node. This means that [service providers](#service-provider) are **allowed** to
+access a user's data, courtesy of that user. It also implies that that user can
+choose to block access of any [service provider](#service-provider) at any
+point in time and move to a different [service provider](#service-provider). In
+this new model, [service providers](#service-provider) need to fight for access
+to that user data and any user-compromising service can simply be left behind.
+
+Within the context of this project, you store your identity claims inside a
+[cryptographic key](#cryptographic-key). You can then use any compatible client
+software or website to verify these claims. And if you don't like that
+particular client software or website, you just choose to use a different one.
+
+## DOIP
+
+A protocol that describes how interactions between
+[cryptographic keys](#cryptographic-key) and
+[service providers](#service-provider) can be used to the advantage of the
+people on the internet and allow them to publicly verify their online
+[identity](#identity) in a secure manner that is resistant to impersonation.
+
+Currently, this documentation is the most elaborate description of the inner
+workings of the DOIP protocol. Drafting a standard is planned.
+
+## Fingerprint
+
+A string of hexadecimal characters that uniquely identifies a
+[cryptographic key](#cryptographic-key).
+
+Within the context of this project, they are used to link a [profile](#profile)
+page back to a single [cryptographic key](#cryptographic-key) by mentioning this
+fingerprint anywhere on the [profile](#profile) page, like inside a biography.
+
+## Identity
+
+Within the context of this project, identity refers to a person's
+**digital online identity**, the collection of [profiles](#profile) that a
+person holds and that partially accounts for a person's online activity. A
+physical person can have multiple online identities, for example a private
+identity and a work-related identity.
+
+That collection of [profiles](#profile) can be stored inside
+[cryptographic key](#cryptographic-key).
+
+## OpenPGP
+
+A standard for [cryptographic keys](#cryptographic-key) defined by
+[RFC 4880](https://tools.ietf.org/html/rfc4880).
+
+## Profile
+
+A piece of data that is created by a physical person but stored and managed on
+the servers of a [service provider](#service-provider). While a person does not
+own that data, it does define them as part of their online
+[identity](#identity).
+
+Usually, a [service provider](#service-provider) generates a profile page based
+on that user data that displays basic information like a username, an avatar and
+a biography.
+
+## Proof
+
+A piece of data provided a [service provider](#service-provider) that contains
+at least some of the data that it stores on a specific user. That piece of data
+also is publicly available to all, usually as a JSON document.
+
+A [claim](#claim) expects the proof to contain a certain statement. For
+[DOIP](#doip), this statement is a [fingerprint](#fingerprint).
+
+For more detailed information, please refer to [Proofs](proofs.md).
+
+## Proxy
+
+A piece of software that handles the request for proof instead of the original
+piece of software that called the proxy. This is useful when doip.js is used in
+browsers. Some [service providers](#service-provider) do not allow their public
+data to be accessed by other websites (so called CORS restrictions,
+[Wikipedia](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing)) but
+requests from non-browser origin are accepted and fulfilled. Doip.js when used
+in a browser will let proxy servers handle their requests for them to eliminate
+this friction.
+
+Doip.js requires a proxy server to run the open source
+[doip-proxy software](https://codeberg.org/keyoxide/doip-proxy).
+
+## Service provider
+
+A company, organization or protocol that stores [profiles](#profile) submitted
+by their users. The data associated to those [profiles](#profile) should at
+least be partially made publicly available to allow identity verification using
+[DOIP](#doip).
+
+For more information, please refer to [Service providers](serviceproviders.md).