crowd-funder-for-time-pwa/src/libs/didPeer.ts

import asn1 from "asn1-ber";
import { Buffer } from "buffer/";
import { decode as cborDecode } from "cbor-x";
import { bytesToMultibase, JWTPayload, multibaseToBytes } from "did-jwt";
import { DIDResolutionResult } from "did-resolver";
import { sha256 } from "ethereum-cryptography/sha256.js";
import {
  startAuthentication,
  startRegistration,
} from "@simplewebauthn/browser";
import {
  generateAuthenticationOptions,
  generateRegistrationOptions,
  verifyAuthenticationResponse,
  verifyRegistrationResponse,
} from "@simplewebauthn/server";
import { VerifyAuthenticationResponseOpts } from "@simplewebauthn/server/esm/authentication/verifyAuthenticationResponse";
import {
  Base64URLString,
  PublicKeyCredentialCreationOptionsJSON,
  PublicKeyCredentialRequestOptionsJSON,
} from "@simplewebauthn/types";

import { getWebCrypto, unwrapEC2Signature } from "@/libs/crypto/passkeyHelpers";

const PEER_DID_PREFIX = "did:peer:0";
export interface JWK {
  kty: string;
  crv: string;
  x: string;
  y: string;
}
export interface PublicKeyCredential {
  rawId: Uint8Array;
  jwt: JWK;
}

function toBase64Url(anythingB64: string) {
  return anythingB64.replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
}

function arrayToBase64Url(anything: Uint8Array) {
  return toBase64Url(Buffer.from(anything).toString("base64"));
}

export async function registerCredential(passkeyName?: string) {
  const options: PublicKeyCredentialCreationOptionsJSON =
    await generateRegistrationOptions({
      rpName: "Time Safari",
      rpID: window.location.hostname,
      userName: passkeyName || "Time Safari User",
      // Don't prompt users for additional information about the authenticator
      // (Recommended for smoother UX)
      attestationType: "none",
      authenticatorSelection: {
        // Defaults
        residentKey: "preferred",
        userVerification: "preferred",
        // Optional
        authenticatorAttachment: "platform",
      },
    });
  // someday, instead of simplwebauthn, we'll go direct: navigator.credentials.create with PublicKeyCredentialCreationOptions
  // with pubKeyCredParams: { type: "public-key", alg: -7 }
  const attResp = await startRegistration(options);
  const verification = await verifyRegistrationResponse({
    response: attResp,
    expectedChallenge: options.challenge,
    expectedOrigin: window.location.origin,
    expectedRPID: window.location.hostname,
  });

  // references for parsing auth data and getting the public key
  // https://github.com/MasterKale/SimpleWebAuthn/blob/master/packages/server/src/helpers/parseAuthenticatorData.ts#L11
  // https://chatgpt.com/share/78a5c91d-099d-46dc-aa6d-fc0c916509fa
  // https://chatgpt.com/share/3c13f061-6031-45bc-a2d7-3347c1e7a2d7

  const credIdBase64Url = verification.registrationInfo?.credentialID as string;
  const credIdHex = Buffer.from(
    base64URLStringToArrayBuffer(credIdBase64Url),
  ).toString("hex");
  const { publicKeyJwk } = cborToKeys(
    verification.registrationInfo?.credentialPublicKey as Uint8Array,
  );

  return {
    authData: verification.registrationInfo?.attestationObject,
    credIdHex: credIdHex,
    rawId: new Uint8Array(new Buffer(attResp.rawId, "base64")),
    publicKeyJwk: publicKeyJwk,
    publicKeyBytes: verification.registrationInfo
      ?.credentialPublicKey as Uint8Array,
  };
}

export function createPeerDid(publicKeyBytes: Uint8Array) {
  // https://github.com/decentralized-identity/veramo/blob/next/packages/did-provider-peer/src/peer-did-provider.ts#L67
  //const provider = new PeerDIDProvider({ defaultKms: LOCAL_KMS_NAME });
  const methodSpecificId = bytesToMultibase(
    publicKeyBytes,
    "base58btc",
    "p256-pub",
  );
  return PEER_DID_PREFIX + methodSpecificId;
}

function peerDidToPublicKeyBytes(did: string) {
  return multibaseToBytes(did.substring(PEER_DID_PREFIX.length));
}

export class PeerSetup {
  public authenticatorData?: ArrayBuffer;
  public challenge?: Uint8Array;
  public clientDataJsonBase64Url?: Base64URLString;
  public signature?: Base64URLString;

  public async createJwtSimplewebauthn(fullPayload: object, credIdHex: string) {
    const credentialId = arrayBufferToBase64URLString(
      Buffer.from(credIdHex, "hex").buffer,
    );
    this.challenge = new Uint8Array(Buffer.from(JSON.stringify(fullPayload)));
    // const payloadHash: Uint8Array = sha256(this.challenge);
    const options: PublicKeyCredentialRequestOptionsJSON =
      await generateAuthenticationOptions({
        challenge: this.challenge,
        rpID: window.location.hostname,
        allowCredentials: [{ id: credentialId }],
      });
    // console.log("simple authentication options", options);

    const clientAuth = await startAuthentication(options);
    // console.log("simple credential get", clientAuth);

    const authenticatorDataBase64Url = clientAuth.response.authenticatorData;
    this.authenticatorData = Buffer.from(
      clientAuth.response.authenticatorData,
      "base64",
    ).buffer;
    this.clientDataJsonBase64Url = clientAuth.response.clientDataJSON;
    // console.log("simple authenticatorData for signing", this.authenticatorData);
    this.signature = clientAuth.response.signature;

    // Our custom type of JWANT means the signature is based on a concatenation of the two Webauthn properties
    const header: JWTPayload = { typ: "JWANT", alg: "ES256" };
    const headerBase64 = Buffer.from(JSON.stringify(header))
      .toString("base64")
      .replace(/\+/g, "-")
      .replace(/\//g, "_")
      .replace(/=+$/, "");

    const dataInJwt = {
      AuthenticationData: authenticatorDataBase64Url,
      ClientDataJSON: this.clientDataJsonBase64Url,
    };
    const dataInJwtString = JSON.stringify(dataInJwt);
    const payloadBase64 = Buffer.from(dataInJwtString).toString("base64");

    const signature = clientAuth.response.signature;

    return headerBase64 + "." + payloadBase64 + "." + signature;
  }

  public async createJwtNavigator(fullPayload: object, credIdHex: string) {
    const dataToSignString = JSON.stringify(fullPayload);
    const dataToSignBuffer = Buffer.from(dataToSignString);
    const credentialId = Buffer.from(credIdHex, "hex");

    // console.log("lower credentialId", credentialId);
    this.challenge = new Uint8Array(dataToSignBuffer);
    const options = {
      publicKey: {
        allowCredentials: [
          {
            id: credentialId,
            type: "public-key",
          },
        ],
        challenge: this.challenge.buffer,
        rpID: window.location.hostname,
        userVerification: "preferred",
      },
    };

    const credential = await navigator.credentials.get(options);
    // console.log("nav credential get", credential);

    this.authenticatorData = credential?.response.authenticatorData;
    const authenticatorDataBase64Url = arrayBufferToBase64URLString(
      this.authenticatorData,
    );

    this.clientDataJsonBase64Url = arrayBufferToBase64URLString(
      credential?.response.clientDataJSON,
    );

    // Our custom type of JWANT means the signature is based on a concatenation of the two Webauthn properties
    const header: JWTPayload = { typ: "JWANT", alg: "ES256" };
    const headerBase64 = Buffer.from(JSON.stringify(header))
      .toString("base64")
      .replace(/\+/g, "-")
      .replace(/\//g, "_")
      .replace(/=+$/, "");

    const dataInJwt = {
      AuthenticationData: authenticatorDataBase64Url,
      ClientDataJSON: this.clientDataJsonBase64Url,
    };
    const dataInJwtString = JSON.stringify(dataInJwt);
    const payloadBase64 = Buffer.from(dataInJwtString)
      .toString("base64")
      .replace(/\+/g, "-")
      .replace(/\//g, "_")
      .replace(/=+$/, "");

    const origSignature = Buffer.from(credential?.response.signature)
      .toString("base64")
    this.signature = origSignature
      .replace(/\+/g, "-")
      .replace(/\//g, "_")
      .replace(/=+$/, "");

    const jwt = headerBase64 + "." + payloadBase64 + "." + this.signature;
    return jwt;
  }

  // return a low-level signing function, similar to createJWS approach
  // async webAuthnES256KSigner(credentialID: string) {
  //   return async (data: string | Uint8Array) => {
  //     // get signature from WebAuthn
  //     const signature = await this.generateWebAuthnSignature(data);
  //
  //     // This converts from the browser ArrayBuffer to a Node.js Buffer, which is a requirement for the asn1 library.
  //     const signatureBuffer = Buffer.from(signature);
  //     console.log("lower signature inside signer", signature);
  //     console.log("lower buffer signature inside signer", signatureBuffer);
  //     console.log("lower base64 buffer signature inside signer", signatureBuffer.toString("base64"));
  //     // Decode the DER-encoded signature to extract R and S values
  //     const reader = new asn1.BerReader(signatureBuffer);
  //     console.log("lower after reader");
  //     reader.readSequence();
  //     console.log("lower after read sequence");
  //     const r = reader.readString(asn1.Ber.Integer, true);
  //     console.log("lower after r");
  //     const s = reader.readString(asn1.Ber.Integer, true);
  //     console.log("lower after r & s");
  //
  //     // Ensure R and S are 32 bytes each
  //     const rBuffer = Buffer.from(r);
  //     const sBuffer = Buffer.from(s);
  //     console.log("lower after rBuffer & sBuffer", rBuffer, sBuffer);
  //     const rWithoutPrefix = rBuffer.length > 32 ? rBuffer.slice(1) : rBuffer;
  //     const sWithoutPrefix = sBuffer.length > 32 ? sBuffer.slice(1) : sBuffer;
  //     const rPadded =
  //       rWithoutPrefix.length < 32
  //         ? Buffer.concat([Buffer.alloc(32 - rWithoutPrefix.length), rBuffer])
  //         : rWithoutPrefix;
  //     const sPadded =
  //       rWithoutPrefix.length < 32
  //         ? Buffer.concat([Buffer.alloc(32 - sWithoutPrefix.length), sBuffer])
  //         : sWithoutPrefix;
  //
  //     // Concatenate R and S to form the 64-byte array (ECDSA signature format expected by JWT)
  //     const combinedSignature = Buffer.concat([rPadded, sPadded]);
  //     console.log(
  //       "lower combinedSignature",
  //       combinedSignature.length,
  //       combinedSignature,
  //     );
  //
  //     const combSig64 = combinedSignature.toString("base64");
  //     console.log("lower combSig64", combSig64);
  //     const combSig64Url = combSig64
  //       .replace(/\+/g, "-")
  //       .replace(/\//g, "_")
  //       .replace(/=+$/, "");
  //     console.log("lower combSig64Url", combSig64Url);
  //     return combSig64Url;
  //   };
  // }
}

// I'd love to use this but it doesn't verify.
// Requires:
// npm install @noble/curves
// ... and this import:
// import { p256 } from "@noble/curves/p256";
export async function verifyJwtP256(
  credIdHex: string,
  rawId: Uint8Array,
  did: string,
  authenticatorData: ArrayBuffer,
  challenge: Uint8Array,
  clientDataJsonBase64Url: Base64URLString,
  signature: Base64URLString,
) {
  const authDataFromBase = Buffer.from(authenticatorData);
  const clientDataFromBase = Buffer.from(clientDataJsonBase64Url, "base64");
  const sigBuffer = Buffer.from(signature, "base64");
  const finalSigBuffer = unwrapEC2Signature(sigBuffer);
  const publicKeyBytes = peerDidToPublicKeyBytes(did);

  // Hash the client data
  const hash = sha256(clientDataFromBase);

  // Construct the preimage
  const preimage = Buffer.concat([authDataFromBase, hash]);

  const isValid = p256.verify(
    finalSigBuffer,
    new Uint8Array(preimage),
    publicKeyBytes,
  );
  return isValid;
}

export async function verifyJwtSimplewebauthn(
  credIdHex: string,
  rawId: Uint8Array,
  did: string,
  authenticatorData: ArrayBuffer,
  challenge: Uint8Array,
  clientDataJsonBase64Url: Base64URLString,
  signature: Base64URLString,
) {
  const authData = arrayToBase64Url(Buffer.from(authenticatorData));
  const publicKeyBytes = peerDidToPublicKeyBytes(did);
  const credId = arrayBufferToBase64URLString(
    Buffer.from(credIdHex, "hex").buffer,
  );
  const authOpts: VerifyAuthenticationResponseOpts = {
    authenticator: {
      credentialID: credId,
      credentialPublicKey: publicKeyBytes,
      counter: 0,
    },
    expectedChallenge: arrayToBase64Url(challenge),
    expectedOrigin: window.location.origin,
    expectedRPID: window.location.hostname,
    response: {
      authenticatorAttachment: "platform",
      clientExtensionResults: {},
      id: credId,
      rawId: arrayToBase64Url(rawId),
      response: {
        authenticatorData: authData,
        clientDataJSON: clientDataJsonBase64Url,
        signature: signature,
      },
      type: "public-key",
    },
  };
  const verification = await verifyAuthenticationResponse(authOpts);
  return verification.verified;
}

export async function verifyJwtWebCrypto(
  credId: Base64URLString,
  rawId: Uint8Array,
  did: string,
  authenticatorData: ArrayBuffer,
  challenge: Uint8Array,
  clientDataJsonBase64Url: Base64URLString,
  signature: Base64URLString,
) {
  const authDataFromBase = Buffer.from(authenticatorData);
  const clientDataFromBase = Buffer.from(clientDataJsonBase64Url, "base64");
  const sigBuffer = Buffer.from(signature, "base64");
  const finalSigBuffer = unwrapEC2Signature(sigBuffer);

  // Hash the client data
  const hash = sha256(clientDataFromBase);

  // Construct the preimage
  const preimage = Buffer.concat([authDataFromBase, hash]);

  const WebCrypto = await getWebCrypto();
  const verifyAlgorithm = {
    name: "ECDSA",
    hash: { name: "SHA-256" },
  };
  const publicKeyBytes = peerDidToPublicKeyBytes(did);
  const publicKeyJwk = cborToKeys(publicKeyBytes).publicKeyJwk;
  const keyAlgorithm = {
    name: "ECDSA",
    namedCurve: publicKeyJwk.crv,
  };
  const publicKeyCryptoKey = await WebCrypto.subtle.importKey(
    "jwk",
    publicKeyJwk,
    keyAlgorithm,
    false,
    ["verify"],
  );
  const verified = await WebCrypto.subtle.verify(
    verifyAlgorithm,
    publicKeyCryptoKey,
    finalSigBuffer,
    preimage,
  );
  return verified;
}

async function peerDidToDidDocument(did: string): Promise<DIDResolutionResult> {
  if (!did.startsWith("did:peer:0z")) {
    throw new Error(
      "This only verifies a peer DID, method 0, encoded base58btc.",
    );
  }
  // this is basically hard-coded from https://www.w3.org/TR/did-core/#example-various-verification-method-types
  // (another reference is the @aviarytech/did-peer resolver)
  const id = did.split(":")[2];
  const multibase = id.slice(1);
  const encnumbasis = multibase.slice(1);
  const didDocument = {
    "@context": [
      "https://www.w3.org/ns/did/v1",
      "https://w3id.org/security/suites/jws-2020/v1",
    ],
    assertionMethod: [did + "#" + encnumbasis],
    authentication: [did + "#" + encnumbasis],
    capabilityDelegation: [did + "#" + encnumbasis],
    capabilityInvocation: [did + "#" + encnumbasis],
    id: did,
    keyAgreement: undefined,
    service: undefined,
    verificationMethod: [
      {
        controller: did,
        id: did + "#" + encnumbasis,
        publicKeyMultibase: multibase,
        type: "EcdsaSecp256k1VerificationKey2019",
      },
    ],
  };
  return {
    didDocument,
    didDocumentMetadata: {},
    didResolutionMetadata: { contentType: "application/did+ld+json" },
  };
}

// convert COSE public key to PEM format
function COSEtoPEM(cose: Buffer) {
  // const alg = cose.get(3); // Algorithm
  const x = cose[-2]; // x-coordinate
  const y = cose[-3]; // y-coordinate

  // Ensure the coordinates are in the correct format
  const pubKeyBuffer = Buffer.concat([Buffer.from([0x04]), x, y]);

  // Convert to PEM format
  const pem = `-----BEGIN PUBLIC KEY-----
${pubKeyBuffer.toString("base64")}
-----END PUBLIC KEY-----`;

  return pem;
}

function base64urlDecode(input: string) {
  input = input.replace(/-/g, "+").replace(/_/g, "/");
  const pad = input.length % 4 === 0 ? "" : "====".slice(input.length % 4);
  const str = atob(input + pad);
  const bytes = new Uint8Array(str.length);
  for (let i = 0; i < str.length; i++) {
    bytes[i] = str.charCodeAt(i);
  }
  return bytes.buffer;
}

function base64urlEncode(buffer: ArrayBuffer) {
  const str = String.fromCharCode(...new Uint8Array(buffer));
  return btoa(str).replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
}

// from @simplewebauthn/browser
function arrayBufferToBase64URLString(buffer) {
  const bytes = new Uint8Array(buffer);
  let str = "";
  for (const charCode of bytes) {
    str += String.fromCharCode(charCode);
  }
  const base64String = btoa(str);
  return base64String.replace(/\+/g, "-").replace(/\//g, "_").replace(/=/g, "");
}

// from @simplewebauthn/browser
function base64URLStringToArrayBuffer(base64URLString: string) {
  const base64 = base64URLString.replace(/-/g, "+").replace(/_/g, "/");
  const padLength = (4 - (base64.length % 4)) % 4;
  const padded = base64.padEnd(base64.length + padLength, "=");
  const binary = atob(padded);
  const buffer = new ArrayBuffer(binary.length);
  const bytes = new Uint8Array(buffer);
  for (let i = 0; i < binary.length; i++) {
    bytes[i] = binary.charCodeAt(i);
  }
  return buffer;
}

function cborToKeys(publicKeyBytes: Uint8Array) {
  const jwkObj = cborDecode(publicKeyBytes);
  if (
    jwkObj[1] != 2 || // kty "EC"
    jwkObj[3] != -7 || // alg "ES256"
    jwkObj[-1] != 1 || // crv "P-256"
    jwkObj[-2].length != 32 || // x
    jwkObj[-3].length != 32 // y
  ) {
    throw new Error("Unable to extract key.");
  }
  const publicKeyJwk = {
    alg: "ES256",
    crv: "P-256",
    kty: "EC",
    x: arrayToBase64Url(jwkObj[-2]),
    y: arrayToBase64Url(jwkObj[-3]),
  };
  const publicKeyBuffer = Buffer.concat([
    Buffer.from(jwkObj[-2]),
    Buffer.from(jwkObj[-3]),
  ]);
  return { publicKeyJwk, publicKeyBuffer };
}

async function pemToCryptoKey(pem: string) {
  const binaryDerString = atob(
    pem
      .split("\n")
      .filter((x) => !x.includes("-----"))
      .join(""),
  );
  const binaryDer = new Uint8Array(binaryDerString.length);
  for (let i = 0; i < binaryDerString.length; i++) {
    binaryDer[i] = binaryDerString.charCodeAt(i);
  }
  // console.log("binaryDer", binaryDer.buffer);
  return await window.crypto.subtle.importKey(
    "spki",
    binaryDer.buffer,
    {
      name: "RSASSA-PKCS1-v1_5",
      hash: "SHA-256",
    },
    true,
    ["verify"],
  );
}