#108 x-atomic-signature

Author: joepio

lib/src/client.ts

@@ -1,7 +1,8 @@
-import { Store } from '.';
-import { Commit, serializeDeterministically } from './commit';
+import { getTimestampNow, Store } from '.';
+import { Commit, serializeDeterministically, signToBase64 } from './commit';
 import { parseJsonADResource } from './parse';
 import { Resource } from './resource';
+import { Agent } from '@tomic/lib';
 
 /**
  * Fetches and Parses a Resource. Can fetch through another atomic server if you
@@ -26,6 +27,10 @@ export async function fetchResource(
     tryValidURL(subject);
     const requestHeaders: HeadersInit = new Headers();
     requestHeaders.set('Accept', 'application/ad+json');
+    // Sign the request if there is an agent present
+    store &&
+      store.getAgent() &&
+      (await signRequest(subject, store.getAgent(), requestHeaders));
     let url = subject;
     if (from !== undefined) {
       const newURL = new URL(`${from}/path`);
@@ -116,3 +121,17 @@ export function removeQueryParamsFromURL(subject: string): string {
   // return subject.split('?')[0];
   return subject;
 }
+
+/** Creates an x-atomic-signature header */
+async function signRequest(
+  /** The resource meant to be fetched */
+  subject: string,
+  agent: Agent,
+  headers: Headers,
+): Promise<Headers> {
+  const privateKey = agent.privateKey;
+  const message = `${subject} ${getTimestampNow()}`;
+  const signed = await signToBase64(message, privateKey);
+  headers.set('x-atomic-signature', signed);
+  return headers;
+}

lib/src/commit.ts

@@ -17,6 +17,11 @@ export interface CommitBuilderI {
   destroy?: boolean;
 }
 
+/** Return the current time as Atomic Data timestamp. Milliseconds since unix epoch. */
+export function getTimestampNow(): number {
+  return Math.round(new Date().getTime());
+}
+
 /** A {@link Commit} without its signature, signer and timestamp */
 export class CommitBuilder implements CommitBuilderI {
   subject: string;
@@ -36,8 +41,12 @@ export class CommitBuilder implements CommitBuilderI {
    * Commit which is ready to be sent to an Atomic-Server `/commit` endpoint.
    */
   async sign(privateKey: string, agentSubject: string): Promise<Commit> {
-    const now: number = Math.round(new Date().getTime());
-    const commit = await signAt(this.clone(), agentSubject, privateKey, now);
+    const commit = await signAt(
+      this.clone(),
+      agentSubject,
+      privateKey,
+      getTimestampNow(),
+    );
     return commit;
   }