Expand signature validation with the output of the signature together…

src/token/token.service.ts

@@ -1,6 +1,7 @@
 //SDPX-License-Identifier: MIT
 //SDPX-FileCopyrightText: 2022 Philip Rebbe <rebbe.philip@fau.de>
 //SDPX-FileCopyrightText: 2022 Raghunandan Arava <raghunandan.arava@fau.de>
+//SDPX-FileCopyrightText: 2022 Sarah Julia Kriesch <sarah.j.kriesch@fau.de>
 
 import { HttpException, HttpStatus, Inject, Injectable } from '@nestjs/common';
 import * as jose from 'jose';
@@ -10,6 +11,7 @@ import * as qs from 'qs';
 import { DiscoveryService } from '../discovery/discovery.service';
 import * as fs from 'fs';
 import { GetKeyFunction } from 'jose/dist/types/types';
+import { generateKeyPair } from 'jose/util/generate_key_pair.ts';
 import { SettingsService } from '../settings/settings.service';
 import { HelperService } from '../helper/helper.service';
 
@@ -94,13 +96,14 @@ export class TokenService {
     return await this.getToken(String(issuer.token_endpoint), grantBody);
   }
 
-  async decodeToken(tokenString: string): Promise<[string, string]> {
-    const [header, payload] = this.decodeTokenString(tokenString);
+  async decodeToken(tokenString: string): Promise<[string, string, string]> {
+    const [header, payload, signature] = this.decodeTokenString(tokenString);
 
     const formattedHeader = JSON.stringify(header, undefined, 2);
     const formattedPayload = JSON.stringify(payload, undefined, 2);
+    const formattedSignature = JSON.stringify(signature, undefined, 2);
 
-    return [formattedHeader, formattedPayload];
+    return [formattedHeader, formattedPayload, formattedSignature];
   }
 
   async validateTokenSignature(
@@ -137,7 +140,7 @@ export class TokenService {
     );
   }
 
-  private decodeTokenString(tokenString: string): [string, string] {
+  private decodeTokenString(tokenString: string): [string, string, string] {
     if (tokenString === undefined || tokenString === '') {
       throw new HttpException('There was no token to decode!', 400);
     }
@@ -150,14 +153,37 @@ export class TokenService {
 
     const header = this.decodeBase64EncodedString(tokenParts[0]);
     const body = this.decodeBase64EncodedString(tokenParts[1]);
+    const signature = this.extractSignature(tokenParts[2]);
 
-    return [header, body];
+
+    return [header, body, signature];
   }
 
   private decodeBase64EncodedString(input: string): string {
     return JSON.parse(new TextDecoder().decode(jose.base64url.decode(input)));
   }
 
+  private async extractSignature(
+    algorithm: string,
+    filepath: string,
+    publicKey: KeyLike,
+    privateKey: KeyLike
+  ): Promise<string, string, string> {
+    let message = '';
+    let isValid = true;
+    try {
+      const keyMaterial = await this.getFileKeyMaterial (algorithm, filepath);
+      const pubKey = await jose.exportSPKI(publicKey);
+      const privKey = await jose.exportPKCS8(privateKey);
+
+      return [algorithm, privKey, pubKey];
+    } catch (error) {
+      isValid = false;
+      message = `The signature is invalid: ${error}`;
+    }
+
+  }
+
   private async validateTokenStringWithExternalKeys(
     tokenString: string,
     issuer: string,