feature/attestation: Add secondsToExpiry

package.json

@@ -9,7 +9,7 @@
     "dist"
   ],
   "scripts": {
-    "test": "jest",
+    "test": "jest --verbose",
     "build": "tsup"
   },
   "repository": {

src/index.ts

@@ -28,7 +28,17 @@ type AttestationPayload = {
    */
   extrefs: Array<object>;
 
-  // TODO location, gtin, exp, iat, aud, _v etc
+  /**
+   * Expiry date, see PASETO-docs for details.
+   */
+  exp: string;
+
+  /**
+   * Issuing date, see PASETO-docs for details
+   */
+  iat: string;
+
+  // TODO location, gtin, aud, _v etc
 }
 
 /**
@@ -104,7 +114,20 @@ class Attestation {
    */
   public getPayload(): AttestationPayload {
     return this.payload;
+  }
+
+  /**
+   * Provides time to expiry relative to a `from` time. Returns negative numbers if expired.
+   * @param from The reference time, Date.now() if not provided 
+   * @returns Seconds left until expiry in seconds.
+   */
+  public secondsToExpiry(from: string | Date = new Date()): number {
+    const expiration = new Date(this.payload.exp).getTime();
+    const fromTime = from ? new Date(from!).getTime() : Date.now();
+
+    const timeLeft: number = expiration - fromTime;
 
+    return timeLeft / 1000.0;
   }
 }
 

tests/attestation.test.ts

@@ -0,0 +1,46 @@
+import { AttestationError, attestationDecoder} from '../src';
+import { describe, test, expect } from "@jest/globals"
+
+const KEY_ID = "k4.pid.2uab3h18sgaYX1PKFW3OIMvGIfAMnuwWBJ6TuCbuwQii";
+const KEY_PUBKEY = "k4.public.f2AxH__c3AQy_abwIYAZvwzLYrLPAUNH5o6cFzPj1_0";
+
+
+describe('Attestation utility tests', () => {  
+  // This token will expire 2030-01-01T00:00:00Z. Expect the test to fail then!
+  const testToken: string = "v4.public.eyJhdWQiOiJleGFtcGxlLmNvbSIsImV4cCI6IjIwMzAtMDEtMDFUMDA6MDA6MDBaIiwiaWF0IjoiMjAyMy0wNC0yMFQxNjo1NDowMVoiLCJqdGkiOiJmOGIxZDdmNzNiNzEzYWY0M2FkNTllMzNiN2MwMmRmNSIsInJlc3VsdCI6IkFVVEhFTlRJQyIsInNsaWQiOiJaNDVKQkpSNlM5IiwibG9jYXRpb24iOnsibGF0Ijo0Ny43OTQ2LCJsb24iOjEyLjk4NjR9LCJleHRyZWZzIjpbImZvbyIseyJiYXIiOiJiYXoifSwxMjNdffeoKRK7wfueWl9ti4h9JTYM2ZOXOPgHMOq-6eRxFEKFUYz1LLcNxUp9JtHHY-FD5pHxP9OQ9nOg_izxMwK3GgU.eyJraWQiOiAiazQucGlkLjJ1YWIzaDE4c2dhWVgxUEtGVzNPSU12R0lmQU1udXdXQko2VHVDYnV3UWlpIn0";
+
+  beforeEach(() => {
+    // From https://docs.authenticvision.com/sdk/pdf/sip-v4-paseto.pdf
+    attestationDecoder.clearCaches();
+    attestationDecoder.addKey(KEY_ID, KEY_PUBKEY)
+  });
+
+  it('SecondsToExpiry relative to defined time', async () => {
+    const attestation = await attestationDecoder.decode(testToken);
+    const SecondsBeforeExpiry = "2029-12-31T23:59:30Z"; // 30 sec left
+    // TODO maybe add tests that define the tolerance, i.e. to how many MS is this accurate etc
+    expect(attestation?.secondsToExpiry(SecondsBeforeExpiry)).toEqual(30.0);
+  });
+
+  it('SecondsToExpiry relative to defined time', async () => {
+    const attestation = await attestationDecoder.decode(testToken);
+    const timeNow = new Date().getTime();
+    const expTime = new Date(attestation!.getPayload().exp).getTime()
+
+    // time left
+    // Note this test will start failing starting 2030-01-01, because the time left becomes negative!
+    const timeInSecondsLeft = (expTime - timeNow) / 1000.0;
+    const eps = 0.5; // 0.5 sec grace for test runtime
+    expect(attestation?.secondsToExpiry()).toBeGreaterThanOrEqual(timeInSecondsLeft);
+    expect(attestation?.secondsToExpiry()).toBeLessThanOrEqual(timeInSecondsLeft + eps);
+  });
+
+  it('SecondsToExpiry negative if expired', async () => {
+    const attestation = await attestationDecoder.decode(testToken);
+    const SecondsBeforeExpiry = "2030-01-01T00:01:00Z"; // expired for 60sec
+    // TODO maybe add tests that define the tolerance, i.e. to how many MS is this accurate etc
+    expect(attestation?.secondsToExpiry(SecondsBeforeExpiry)).toEqual(-60.0);
+  });
+
+
+});