Implement 0.8 spec (#52)

* Adapt to 0.8 spec

* Readme feedback

Author: icidasset

.eslintrc.js

@@ -13,19 +13,20 @@ module.exports = {
     "plugin:@typescript-eslint/recommended",
   ],
   rules: {
-    "@typescript-eslint/member-delimiter-style": ["error", {
+    "@typescript-eslint/member-delimiter-style": [ "error", {
       "multiline": {
         "delimiter": "none",
         "requireLast": false
       },
-    }],
-    "@typescript-eslint/no-use-before-define": ["off"],
-    "@typescript-eslint/semi": ["error", "never"],
+    } ],
+    "@typescript-eslint/no-use-before-define": [ "off" ],
+    "@typescript-eslint/semi": [ "error", "never" ],
     "@typescript-eslint/ban-ts-comment": 1,
-    "@typescript-eslint/quotes": ["error", "double", {
+    "@typescript-eslint/quotes": [ "error", "double", {
       allowTemplateLiterals: true
-    }],
+    } ],
     // If you want to *intentionally* run a promise without awaiting, prepend it with "void " instead of "await "
-    "@typescript-eslint/no-floating-promises": ["error"],
+    "@typescript-eslint/no-floating-promises": [ "error" ],
+    "@typescript-eslint/no-inferrable-types": [ "off" ],
   }
 }

README.md

@@ -9,7 +9,6 @@ At a high level, UCANs (“User Controlled Authorization Network”) are an auth
 
 No all-powerful authorization server or server of any kind is required for UCANs. Instead, everything a user can do is captured directly in a key or token, which can be sent to anyone who knows how to interpret the UCAN format. Because UCANs are self-contained, they are easy to consume permissionlessly, and they work well offline and in distributed systems.
 
-
 UCANs work
 - Server -> Server
 - Client -> Server
@@ -20,14 +19,18 @@ UCANs work
 Read more in the whitepaper: https://whitepaper.fission.codes/access-control/ucan
 
 
+
 ## Structure
- ### Header
+
+### Header
+
  `alg`, Algorithm, the type of signature.
 
  `typ`, Type, the type of this data structure, JWT.
 
  `uav`, UCAN version.
- ### Payload
+
+### Payload
 
  `att`, Attenuation, a list of resources and capabilities that the ucan grants.
 
@@ -44,41 +47,52 @@ Read more in the whitepaper: https://whitepaper.fission.codes/access-control/uca
  `prf`, Proof, an optional nested token with equal or greater privileges.
 
  ### Signature
+
  A signature (using `alg`) of the base64 encoded header and payload concatenated together and delimited by `.`
 
-## Build params
-Use `ucan.build` to help in formatting and signing a ucan. It takes the following parameters
+
+
+## Build
+
+`ucan.build` can be used to help in formatting and signing a UCAN. It takes the following parameters:
 ```ts
-export type BuildParams = {
-  // to/from
-  audience: string
+type BuildParams = {
+  // from/to
   issuer: Keypair
+  audience: string
 
   // capabilities
-  capabilities: Array<Capability>
+  capabilities?: Array<Capability>
 
   // time bounds
   lifetimeInSeconds?: number // expiration overrides lifetimeInSeconds
   expiration?: number
   notBefore?: number
 
-  // proof / other info
+  // proofs / other info
   facts?: Array<Fact>
-  proof?: string
-
-  // in the weeds
-  ucanVersion?: string
+  proofs?: Array<string>
+  addNonce?: boolean
 }
 ```
+
 ### Capabilities
-`capabilities` is an array of resources and permission level formatted as:
+
+`capabilities` is an array of resource pointers and abilities:
 ```ts
 {
-  $TYPE: $IDENTIFIER,
-  "cap": $CAPABILITY
+  // `with` is a resource pointer in the form of a URI, which has a `scheme` and `hierPart`.
+  // → "mailto:boris@fission.codes"
+  with: { scheme: "mailto", hierPart: "boris@fission.codes" },
+
+  // `can` is an ability, which always has a namespace and optional segments.
+  // → "msg/SEND"
+  can: { namespace: "msg", segments: [ "SEND" ] }
 }
 ```
 
+
+
 ## Installation
 
 ### NPM:
@@ -95,25 +109,25 @@ yarn add ucans
 
 ## Example
 ```ts
-import * as ucan from 'ucans'
+import * as ucan from "ucans"
 
 // in-memory keypair
 const keypair = await ucan.EdKeypair.create()
 const u = await ucan.build({
-  audience: "did:key:zabcde...", //recipient DID
-  issuer: keypair, //signing key
+  audience: "did:key:zabcde...", // recipient DID
+  issuer: keypair, // signing key
   capabilities: [ // permissions for ucan
     {
-      "wnfs": "boris.fission.name/public/photos/",
-      "cap": "OVERWRITE"
+      with: { scheme: "wnfs", hierPart: "//boris.fission.name/public/photos/" },
+      can: { namespace: "wnfs", segments: [ "OVERWRITE" ] }
     },
     {
-      "wnfs": "boris.fission.name/private/4tZA6S61BSXygmJGGW885odfQwpnR2UgmCaS5CfCuWtEKQdtkRnvKVdZ4q6wBXYTjhewomJWPL2ui3hJqaSodFnKyWiPZWLwzp1h7wLtaVBQqSW4ZFgyYaJScVkBs32BThn6BZBJTmayeoA9hm8XrhTX4CGX5CVCwqvEUvHTSzAwdaR",
-      "cap": "APPEND"
+      with: { scheme: "wnfs", hierPart: "//boris.fission.name/private/4tZA6S61BSXygmJGGW885odfQwpnR2UgmCaS5CfCuWtEKQdtkRnvKVdZ4q6wBXYTjhewomJWPL2ui3hJqaSodFnKyWiPZWLwzp1h7wLtaVBQqSW4ZFgyYaJScVkBs32BThn6BZBJTmayeoA9hm8XrhTX4CGX5CVCwqvEUvHTSzAwdaR" },
+      can: { namespace: "wnfs", segments: [ "APPEND" ] }
     },
     {
-      "email": "boris@fission.codes",
-      "cap": "SEND"
+      with: { scheme: "mailto", hierPart: "boris@fission.codes" },
+      can: { namespace: "wnfs", segments: [ "SEND" ] }
     }
   ]
 })
@@ -124,6 +138,8 @@ const payload = await ucan.buildPayload(...)
 const u = await ucan.sign(payload, keyType, signingFn)
 ```
 
+
+
 ## Sponsors
 
 Sponsors that contribute developer time or resources to this implementation of UCANs:
@@ -133,4 +149,5 @@ Sponsors that contribute developer time or resources to this implementation of U
 
 
 ## UCAN Toucan
+
 ![](https://ipfs.runfission.com/ipfs/QmcyAwK7AjvLXbGuL4cqG5nufEKJquFmFGo2SDsaAe939Z)

package.json

@@ -33,11 +33,13 @@
   "dependencies": {
     "@stablelib/ed25519": "^1.0.2",
     "one-webcrypto": "^1.0.1",
+    "semver": "^7.3.5",
     "uint8arrays": "^3.0.0"
   },
   "devDependencies": {
     "@types/jest": "^27.0.1",
     "@types/node": "^16.9.1",
+    "@types/semver": "^7.3.9",
     "@typescript-eslint/eslint-plugin": "^5.5.0",
     "@typescript-eslint/parser": "^5.5.0",
     "eslint": "^8.3.0",

src/attenuation.ts

@@ -1,9 +1,13 @@
-// https://whitepaper.fission.codes/access-control/ucan/jwt-authentication#attenuation
-import { Capability, Ucan } from "./types"
+// https://github.com/ucan-wg/spec/blob/dd4ac83f893cef109f5a26b07970b2484f23aabf/README.md#325-attenuation-scope
+import { Capability } from "./capability"
 import { Chained } from "./chained"
+import { Ucan } from "./types"
 import * as util from "./util"
 
 
+// TYPES
+
+
 export interface CapabilitySemantics<A> {
   /**
    * Try to parse a capability into a representation used for
@@ -14,6 +18,7 @@ export interface CapabilitySemantics<A> {
    * return `null`.
    */
   tryParsing(cap: Capability): A | null
+
   /**
    * This figures out whether a given `childCap` can be delegated from `parentCap`.
    * There are three possible results with three return types respectively:
@@ -22,62 +27,57 @@ export interface CapabilitySemantics<A> {
    * - `CapabilityEscalation<A>`: It's clear that `childCap` is meant to be delegated from `parentCap`, but there's a rights escalation.
    */
   tryDelegating(parentCap: A, childCap: A): A | null | CapabilityEscalation<A>
-  // TODO builders
 }
 
+export type CapabilityResult<A>
+  = CapabilityWithInfo<A>
+  | CapabilityEscalation<A>
 
 export interface CapabilityInfo {
   originator: string // DID
   expiresAt: number
   notBefore?: number
 }
 
-
 export interface CapabilityWithInfo<A> {
   info: CapabilityInfo
   capability: A
 }
 
-
-export type CapabilityResult<A>
-  = CapabilityWithInfo<A>
-  | CapabilityEscalation<A>
-
-
 export interface CapabilityEscalation<A> {
   escalation: string // reason
   capability: A // the capability that escalated rights
 }
 
+
+
+// TYPE CHECKING
+
+
 export function isCapabilityEscalation<A>(obj: unknown): obj is CapabilityEscalation<A> {
   return util.isRecord(obj)
     && util.hasProp(obj, "escalation") && typeof obj.escalation === "string"
     && util.hasProp(obj, "capability")
 }
 
-export function hasCapability<Cap>(semantics: CapabilitySemantics<Cap>, capability: CapabilityWithInfo<Cap>, ucan: Chained): CapabilityWithInfo<Cap> | false {
-  for (const cap of capabilities(ucan, semantics)) {
-    if (isCapabilityEscalation(cap)) {
-      continue
-    }
 
-    const delegatedCapability = semantics.tryDelegating(cap.capability, capability.capability)
 
-    if (isCapabilityEscalation(delegatedCapability)) {
-      continue
-    }
+// PARSING
 
-    if (delegatedCapability != null) {
-      return {
-        info: delegateCapabilityInfo(capability.info, cap.info),
-        capability: delegatedCapability,
-      }
-    }
-  }
 
-  return false
+function parseCapabilityInfo(ucan: Ucan<never>): CapabilityInfo {
+  return {
+    originator: ucan.payload.iss,
+    expiresAt: ucan.payload.exp,
+    ...(ucan.payload.nbf != null ? { notBefore: ucan.payload.nbf } : {}),
+  }
 }
 
+
+
+// FUNCTIONS
+
+
 export function canDelegate<A>(semantics: CapabilitySemantics<A>, capability: A, ucan: Chained): boolean {
   for (const cap of capabilities(ucan, semantics)) {
     if (isCapabilityEscalation(cap)) {
@@ -98,7 +98,6 @@ export function canDelegate<A>(semantics: CapabilitySemantics<A>, capability: A,
   return false
 }
 
-
 export function capabilities<A>(
   ucan: Chained,
   capability: CapabilitySemantics<A>,
@@ -171,10 +170,29 @@ function delegateCapabilityInfo(childInfo: CapabilityInfo, parentInfo: Capabilit
   }
 }
 
-function parseCapabilityInfo(ucan: Ucan<never>): CapabilityInfo {
-  return {
-    originator: ucan.payload.iss,
-    expiresAt: ucan.payload.exp,
-    ...(ucan.payload.nbf != null ? { notBefore: ucan.payload.nbf } : {}),
+export function hasCapability<Cap>(
+  semantics: CapabilitySemantics<Cap>,
+  capability: CapabilityWithInfo<Cap>,
+  ucan: Chained
+): CapabilityWithInfo<Cap> | false {
+  for (const cap of capabilities(ucan, semantics)) {
+    if (isCapabilityEscalation(cap)) {
+      continue
+    }
+
+    const delegatedCapability = semantics.tryDelegating(cap.capability, capability.capability)
+
+    if (isCapabilityEscalation(delegatedCapability)) {
+      continue
+    }
+
+    if (delegatedCapability != null) {
+      return {
+        info: delegateCapabilityInfo(capability.info, cap.info),
+        capability: delegatedCapability,
+      }
+    }
   }
+
+  return false
 }

src/builder.ts

@@ -1,6 +1,7 @@
 import * as token from "./token"
 import * as util from "./util"
-import { Capability, Keypair, Fact, UcanPayload, isKeypair, isCapability } from "./types"
+import { Keypair, Fact, UcanPayload, isKeypair } from "./types"
+import { Capability, isCapability } from "./capability"
 import { CapabilityInfo, CapabilitySemantics, canDelegate } from "./attenuation"
 import { Chained } from "./chained"
 import { Store } from "./store"
@@ -158,7 +159,7 @@ export class Builder<State extends Partial<BuildableState>> {
     }
     return new Builder(this.state, {
       ...this.defaultable,
-      facts: [...this.defaultable.facts, fact, ...facts]
+      facts: [ ...this.defaultable.facts, fact, ...facts ]
     })
   }
 
@@ -180,7 +181,7 @@ export class Builder<State extends Partial<BuildableState>> {
     }
     return new Builder(this.state, {
       ...this.defaultable,
-      capabilities: [...this.defaultable.capabilities, capability, ...capabilities]
+      capabilities: [ ...this.defaultable.capabilities, capability, ...capabilities ]
     })
   }
 
@@ -231,9 +232,9 @@ export class Builder<State extends Partial<BuildableState>> {
       }
       return new Builder(this.state, {
         ...this.defaultable,
-        capabilities: [...this.defaultable.capabilities, requiredCapability],
+        capabilities: [ ...this.defaultable.capabilities, requiredCapability ],
         proofs: this.defaultable.proofs.find(proof => proof.encoded() === storeOrProof.encoded()) == null
-          ? [...this.defaultable.proofs, storeOrProof]
+          ? [ ...this.defaultable.proofs, storeOrProof ]
           : this.defaultable.proofs
       })
     } else {
@@ -243,9 +244,9 @@ export class Builder<State extends Partial<BuildableState>> {
       if (result.success) {
         return new Builder(this.state, {
           ...this.defaultable,
-          capabilities: [...this.defaultable.capabilities, requiredCapability],
+          capabilities: [ ...this.defaultable.capabilities, requiredCapability ],
           proofs: this.defaultable.proofs.find(proof => proof.encoded() === result.ucan.encoded()) == null
-            ? [...this.defaultable.proofs, result.ucan]
+            ? [ ...this.defaultable.proofs, result.ucan ]
             : this.defaultable.proofs
         })
       } else {