capability-uri

Stability: 1 - Experimental

Contributors

@tristanls

Contents

• Overview
• Installation
• Tests
• Usage
• Documentation
• Releases

Overview

This module documents the capability URI scheme and provides a reference implementation for generating and parsing capability URIs.

Capability URI Scheme

The "cpblty" scheme is used to identify capabilities.

There are two types of "cpblty" URIs. They are distinguished by the mechanism used to identify the authority responsible for resolving the capability.

The first type of capability URI uses IP address or DNS resolution to identify authority.

The second type of capability URI uses first path part of the URI to identify the authority responsible for resolving the capability, allowing for non-IP and non-DNS resolution mechanisms.

The scheme-specific syntax and semantics of capability URIs are as follows:

capability_URI = "cpblty:" "//" authority "/#" capability_token
               / "cpblty:" capability_authority [ "@" authority_scheme ] ":" capability_token
authority_scheme =  ALPHA *( ALPHA / DIGIT / "-" / "_" )
capability_authority = base64url
capability_token = "CPBLTY" version "-" base64url

The semantics are such that the identified authority is the domain containing the capability specified by the capability_token. For full specification of authority, see RFC 3986, Section 3.2 - Authority. Alternatively, the capability_authority, in combination with optional authority_scheme, is the authority containing the capability specified by the capability_token. The string CPBLTY is a well-known string to facilitate searches for leaked capabilities. version is the numeric version of capability_token used. base64url is URL-safe base64 encoded bytes of the specified capability.

Examples

Capability URI using example.com registered DNS name to designate authority:

cpblty://example.com/#CPBLTY1-IbwNerN4Dw4BYlpYc4Az-pNBWen_WsdrTrpb-HmMiJOEHvCv1xHKBn2Q

Capability URI using DkDvHuU78RZGUeNs3Q-Wsw authority to be interpreted using a custom my_dht resolution scheme:

cpblty:DkDvHuU78RZGUeNs3Q-Wsw@my_dht:CPBLTY1-IbwNerN4Dw4BYlpYc4Az-pNBWen_WsdrTrpb-HmMiJOEHvCv1xHKBn2Q

Capability URI using DkDvHuU78RZGUeNs3Q-Wsw authority with an implied resolution scheme:

cpblty:DkDvHuU78RZGUeNs3Q-Wsw:CPBLTY1-IbwNerN4Dw4BYlpYc4Az-pNBWen_WsdrTrpb-HmMiJOEHvCv1xHKBn2Q

Installation

npm install capability-uri

Tests

npm test

Usage

const CapabilityToken = require("capability-token");
const CapabilityURI = require("capability-uri");
const crypto = require("crypto");
const UrlSafeBase64 = require("urlsafe-base64");

const uri1 = CapabilityURI.parse(`cpblty://example.com/#${new CapabilityToken().serialize()}`);
console.log(uri1);
console.log(uri1.serialize());

const uri2 = new CapabilityURI(
    {
        authority: "example.com",
        capabilityToken: new CapabilityToken()
    }
);
console.log(uri2);
console.log(uri2.serialize());

const uri3 = new CapabilityURI(
    {
        capabilityAuthority: UrlSafeBase64.encode(crypto.randomBytes(64)),
        capabilityToken: new CapabilityToken()
    }
);
console.log(uri3);
console.log(uri3.serialize());

const uri4 = new CapabilityURI(
    {
        authorityScheme: "dht",
        capabilityAuthority: UrlSafeBase64.encode(crypto.randomBytes(64)),
        capabilityToken: new CapabilityToken()
    }
);
console.log(uri4);
console.log(uri4.serialize());

Documentation

CapabilityURI

IP/DNS Capability URI

• authority: String Domain containing the capability specified by the capabilityToken. For full specification of authority, see RFC 3986, Section 3.2 - Authority.
• capabilityToken: CapabilityToken CapabilityToken instance.

Other Capability URI

• authorityScheme: String (Default: undefined) Optional authority scheme.
• capabilityAuthority: String Base64url encoded authority containing the capability specified by the capabilityToken.
• capabilityToken: CapabilityToken CapabilityToken instance.

Public API

• CapabilityURI.parse(uri)
• new CapabilityURI(config)
• capabilityUri.serialize()

CapabilityURI.parse(uri)

• uri: String String capability URI to parse.
• Return: CapabilityURI Parsed capability URI, either IP/DNS type or Other type.

new CapabilityURI(config)

• config: Object configuration.
  • authority: String Domain containing the capability specified by the capabilityToken. For full specification of authority, see RFC 3986, Section 3.2 - Authority. Mutually exclusive with capabilityAuthority.
  • authorityScheme: String (Default: undefined) Optional authority scheme.
  • capabilityAuthority: String Base64url encoded authority containing the capability specified by the capabilityToken. Mutually exclusive with authority.
  • capabilityToken: CapabilityToken CapabilityToken instance.
• Return: CapabilityURI Capability URI instance as configured.

Creates a new CapabilityURI instance as configured.

capabilityUri.serialize()

• Return: String Capability URI.

Serializes capabilityUri into a string in URI format.

Releases

Current releases.

Policy

We follow the semantic versioning policy (semver.org) with a caveat:

Given a version number MAJOR.MINOR.PATCH, increment the:

MAJOR version when you make incompatible API changes, MINOR version when you add functionality in a backwards-compatible manner, and PATCH version when you make backwards-compatible bug fixes.

caveat: Major version zero is a special case indicating development version that may make incompatible API changes without incrementing MAJOR version.