Merge pull request #4 from ykocaogullar/main

Addition to backend for WoT, following new roadmap

src/security/inter-trust.ts

@@ -0,0 +1,213 @@
+import { Decoder, Encoder } from '@ndn/tlv';
+import { Data, Interest, Name, Signer, Verifier } from '@ndn/packet';
+import { Certificate, createSigner, createVerifier, ECDSA, ValidityPeriod } from '@ndn/keychain';
+import * as endpoint from '@ndn/endpoint';
+import type { Forwarder } from '@ndn/fw';
+import { Storage } from '../storage/mod.ts';
+import { base64ToBytes } from '@ucla-irl/ndnts-aux/utils';
+import { SecurityAgent } from './types.ts';
+
+/**
+ * A Signer & Verifier that handles security authentication.
+ * CertStorage itself is not a storage, actually. Depend on an external storage.
+ */
+export class InterTrust implements SecurityAgent {
+  private _signer: Signer | undefined;
+  readonly readyEvent: Promise<void>;
+  private trustedNames: string[] = [];
+
+  constructor(
+    readonly trustAnchor: Certificate,
+    readonly ownCertificate: Certificate,
+    readonly storage: Storage,
+    readonly fw: Forwarder,
+    prvKeyBits: Uint8Array,
+  ) {
+    this.readyEvent = (async () => {
+      await this.importCert(trustAnchor);
+      await this.importCert(ownCertificate);
+      const keyPair = await ECDSA.cryptoGenerate({
+        importPkcs8: [prvKeyBits, ownCertificate.publicKeySpki],
+      }, true);
+      this._signer = createSigner(
+        ownCertificate.name.getPrefix(ownCertificate.name.length - 2),
+        ECDSA,
+        keyPair,
+      ).withKeyLocator(ownCertificate.name);
+    })();
+  }
+
+  /** Obtain the signer */
+  get signer() {
+    return this._signer!;
+  }
+
+  /** Obtain this node's own certificate */
+  get certificate() {
+    return this.ownCertificate;
+  }
+
+  /** Import an external certificate into the storage */
+  async importCert(cert: Certificate) {
+    await this.storage.set(cert.name.toString(), Encoder.encode(cert.data));
+  }
+
+  /**
+   * Fetch a certificate based on its name from local storage and then remote.
+   * @param keyName The certificate's name.
+   * @param localOnly If `true`, only look up the local storage without sending an Interest.
+   * @returns The fetched certificate. `undefined` if not found.
+   */
+  async getCertificate(keyName: Name, localOnly: boolean): Promise<Certificate | undefined> {
+    const certBytes = await this.storage.get(keyName.toString());
+    if (certBytes === undefined) {
+      if (localOnly) {
+        return undefined;
+      } else {
+        try {
+          const result = await endpoint.consume(
+            new Interest(
+              keyName,
+              Interest.MustBeFresh,
+              Interest.Lifetime(5000),
+            ),
+            {
+              // Fetched key must be signed by a known key
+              // TODO: Find a better way to handle security
+              verifier: this.localVerifier,
+              retx: 5,
+              fw: this.fw,
+            },
+          );
+
+          // Cache result certificates
+          this.storage.set(result.name.toString(), Encoder.encode(result));
+
+          return Certificate.fromData(result);
+        } catch {
+          return undefined;
+        }
+      }
+    } else {
+      return Certificate.fromData(Decoder.decode(certBytes, Data));
+    }
+  }
+
+  /**
+   * Verify a packet. Throw an error if failed.
+   * @param pkt The packet to verify.
+   * @param localOnly If `true`, only look up the local storage for the certificate.
+   */
+  async verify(pkt: Verifier.Verifiable, localOnly: boolean) {
+    const keyName = pkt.sigInfo?.keyLocator?.name;
+    if (!keyName) {
+      throw new Error(`Data not signed: ${pkt.name.toString()}`);
+    }
+    const cert = await this.getCertificate(keyName, localOnly);
+    if (cert === undefined) {
+      throw new Error(`No certificate: ${pkt.name.toString()} signed by ${keyName.toString()}`);
+    }
+    const verifier = await createVerifier(cert, { algoList: [ECDSA] });
+    try {
+      await verifier.verify(pkt);
+    } catch (error) {
+      throw new Error(`Unable to verify ${pkt.name.toString()} signed by ${keyName.toString()} due to: ${error}`);
+    }
+  }
+
+  /** Obtain an verifier that fetches certificate */
+  get verifier(): Verifier {
+    return {
+      verify: (pkt) => this.verify(pkt, false),
+    };
+  }
+
+  /** Obtain an verifier that does not fetch certificate remotely */
+  get localVerifier(): Verifier {
+    return {
+      verify: (pkt) => this.verify(pkt, true),
+    };
+  }
+
+  public static async create(
+    trustAnchor: Certificate,
+    ownCertificate: Certificate,
+    storage: Storage,
+    fw: Forwarder,
+    prvKeyBits: Uint8Array,
+  ) {
+    const result = new InterTrust(
+      trustAnchor,
+      ownCertificate,
+      storage,
+      fw,
+      prvKeyBits,
+    );
+    await result.readyEvent;
+    return result;
+  }
+
+  //function that takes b64 encoded certificate bytes and returns cert
+  decodeCert = (b64Value: string) => {
+    const wire = base64ToBytes(b64Value);
+    const data = Decoder.decode(wire, Data);
+    const cert = Certificate.fromData(data);
+    return cert;
+  };
+
+  /** Import an external certificate in base64 format into the storage */
+  async importCertAsb64(certb64: string) {
+    const cert = this.decodeCert(certb64); // convert b64 into type Certificate
+    await this.storage.set(cert.name.toString(), Encoder.encode(cert.data)); // put certificate into cache
+  }
+
+  async generatePoR(
+    strangerCert: string, // stranger's certficate in base64 format
+  ): Promise<string> {
+    //function that generates the name of cross signed certificate
+    //this function follows the naming convention described in Intertrust poster
+    const generatePoRName = (strangerKeyname: string, zone_A_certname: string = this.trustAnchor.name.toString()) => {
+      // Construct <Z_a name encoded>
+      const parts: string[] = zone_A_certname.split('/');
+      let zone_A_name: string = '';
+      for (let i = 0; i < parts.length; i++) { //put <Z_a name encoded> together with a loop
+        if (parts[i].includes('KEY')) {
+          break;
+        }
+        zone_A_name += parts[i] + '/';
+      }
+
+      return new Name(strangerKeyname + '/' + zone_A_name + '/v1');
+    };
+
+    const sCert = this.decodeCert(strangerCert); //stranger's cert
+
+    //create validity parameters to be set with .build method later
+    const now = Date.now();
+    const oneHourInMilliseconds = 60 * 60 * 1000; // Number of milliseconds in an hour, change this if you want to adjust validity period
+    const validityPeriodEnd = now + oneHourInMilliseconds;
+    const validityPeriod = new ValidityPeriod();
+    validityPeriod.notBefore = now;
+    validityPeriod.notAfter = validityPeriodEnd;
+
+    //this check is needed because Certificate.build function needs non-null signer
+    if (!this._signer) {
+      throw new Error('Signer is undefined');
+    }
+    // Create a cross-signed certificate, i.e. the PoR
+    const proofOfZoneRecognition = await Certificate.build({
+      name: generatePoRName(sCert.name.toString()),
+      validity: validityPeriod,
+      publicKeySpki: sCert.publicKeySpki, // Now accessing getPublicKey on the Certificate object
+      signer: this._signer,
+    });
+
+    // Cache PoR certificate
+    this.storage.set(proofOfZoneRecognition.name.toString(), Encoder.encode(proofOfZoneRecognition.data));
+
+    // Encode the final certificate to base64 using Node.js Buffer
+    const encodedPoR = Buffer.from(Encoder.encode(proofOfZoneRecognition.data)).toString('base64');
+
+    return encodedPoR; // Return the encoded string
+  }
+}