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chore: add more comments to webauthn verify
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Also move the test function to a test contract
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@cpb8010
cpb8010 committed Feb 12, 2025
1 parent ff8273d commit 5ec5f86
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Showing 3 changed files with 75 additions and 40 deletions.
20 changes: 20 additions & 0 deletions src/test/TestWebAuthValidator.sol
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Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import { WebAuthValidator } from "../validators/WebAuthValidator.sol";

contract WebAuthValidatorTest is WebAuthValidator {
/// @notice Verifies a message using the P256 curve.
/// @dev Useful for testing the P256 precompile
/// @param message The sha256 hash of the authenticator hash and hashed client data
/// @param rs The signature to validate (r, s) from the signed message
/// @param pubKey The public key to validate the signature against (x, y)
/// @return valid true if the signature is valid
function p256Verify(
bytes32 message,
bytes32[2] calldata rs,
bytes32[2] calldata pubKey
) external view returns (bool valid) {
valid = rawVerify(message, rs, pubKey);
}
}
17 changes: 14 additions & 3 deletions src/validators/WebAuthValidator.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ contract WebAuthValidator is VerifierCaller, IModuleValidator {
using JSONParserLib for string;

address private constant P256_VERIFIER = address(0x100);

// check for secure validation: bit 0 = 1 (user present), bit 2 = 1 (user verified)
bytes1 private constant AUTH_DATA_MASK = 0x05;
bytes32 private constant LOW_S_MAX = 0x7fffffff800000007fffffffffffffffde737d56d38bcf4279dce5617e3192a8;
bytes32 private constant HIGH_R_MAX = 0xffffffff00000000ffffffffffffffffbce6faada7179e84f3b9cac2fc632551;
Expand Down Expand Up @@ -103,17 +105,19 @@ contract WebAuthValidator is VerifierCaller, IModuleValidator {
fatSignature
);

// prevent signature replay https://yondon.blog/2019/01/01/how-not-to-use-ecdsa/
if (rs[0] <= 0 || rs[0] > HIGH_R_MAX || rs[1] <= 0 || rs[1] > LOW_S_MAX) {
return false;
}

// check if the flags are set
// https://developer.mozilla.org/en-US/docs/Web/API/Web_Authentication_API/Authenticator_data#attestedcredentialdata
if (authenticatorData[32] & AUTH_DATA_MASK != AUTH_DATA_MASK) {
return false;
}

// parse out the important fields (type, challenge, origin, crossOrigin): https://goo.gl/yabPex
// parse out the required fields (type, challenge, crossOrigin): https://goo.gl/yabPex
JSONParserLib.Item memory root = JSONParserLib.parse(clientDataJSON);
// challenge should contain the transaction hash, ensuring that the transaction is signed
string memory challenge = root.at('"challenge"').value().decodeString();
bytes memory challengeData = Base64.decode(challenge);
if (challengeData.length != 32) {
Expand All @@ -123,11 +127,14 @@ contract WebAuthValidator is VerifierCaller, IModuleValidator {
return false;
}

// type ensures the signature was created from a validation request
string memory type_ = root.at('"type"').value().decodeString();
if (!Strings.equal("webauthn.get", type_)) {
return false;
}

// the origin determines which key to validate against
// as passkeys are linked to domains, so the storage mapping reflects that
string memory origin = root.at('"origin"').value().decodeString();
bytes32[2] memory pubkey;
pubkey[0] = lowerKeyHalf[origin][msg.sender];
Expand All @@ -137,6 +144,10 @@ contract WebAuthValidator is VerifierCaller, IModuleValidator {
return false;
}

// cross-origin validation is optional, but explicitly not supported.
// cross-origin requests would be from embedding the auth request
// from another domain. The current SSO setup uses a pop-up instead of
// an i-frame, so we're rejecting these until the implemention supports it
JSONParserLib.Item memory crossOriginItem = root.at('"crossOrigin"');
if (!crossOriginItem.isUndefined()) {
string memory crossOrigin = crossOriginItem.value();
Expand Down Expand Up @@ -181,7 +192,7 @@ contract WebAuthValidator is VerifierCaller, IModuleValidator {
bytes32 message,
bytes32[2] calldata rs,
bytes32[2] calldata pubKey
) external view returns (bool valid) {
) internal view returns (bool valid) {
valid = callVerifier(P256_VERIFIER, message, rs, pubKey);
}
}
78 changes: 41 additions & 37 deletions test/PasskeyModule.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,15 +5,15 @@ import { ECDSASigValue } from "@peculiar/asn1-ecc";
import { AsnParser } from "@peculiar/asn1-schema";
import { bigintToBuf, bufToBigint } from "bigint-conversion";
import { assert, expect } from "chai";
import { randomBytes } from "crypto";
import { parseEther, ZeroAddress } from "ethers";
import * as hre from "hardhat";
import { encodeAbiParameters, Hex, hexToBytes, toHex } from "viem";
import { SmartAccount, Wallet } from "zksync-ethers";
import { base64UrlToUint8Array } from "zksync-sso/utils";

import { SsoAccount__factory, WebAuthValidator, WebAuthValidator__factory } from "../typechain-types";
import { SsoAccount__factory, WebAuthValidator, WebAuthValidator__factory, WebAuthValidatorTest, WebAuthValidatorTest__factory } from "../typechain-types";
import { ContractFixtures, getProvider, getWallet, LOCAL_RICH_WALLETS, logInfo, RecordedResponse } from "./utils";
import { base64UrlToUint8Array } from "zksync-sso/utils";
import { encodeAbiParameters, Hex, hexToBytes, toHex } from "viem";
import { randomBytes } from "crypto";
import { parseEther, ZeroAddress } from "ethers";

/**
* Decode from a Base64URL-encoded string to an ArrayBuffer. Best used when converting a
Expand All @@ -36,6 +36,14 @@ async function deployValidator(wallet: Wallet): Promise<WebAuthValidator> {
return WebAuthValidator__factory.connect(await validator.getAddress(), wallet);
}

async function deployP256Tester(wallet: Wallet): Promise<WebAuthValidatorTest> {
const deployer: Deployer = new Deployer(hre, wallet);
const passkeyValidatorArtifact = await deployer.loadArtifact("WebAuthValidatorTest");

const validator = await deployer.deploy(passkeyValidatorArtifact, []);
return WebAuthValidatorTest__factory.connect(await validator.getAddress(), wallet);
}

/**
* COSE Keys
*
Expand Down Expand Up @@ -338,9 +346,6 @@ function encodeFatSignature(
clientDataJSON: string;
signature: string;
},
contracts: {
passkey: string;
},
) {
const signature = unwrapEC2Signature(base64UrlToUint8Array(passkeyResponse.signature));
return encodeAbiParameters(
Expand All @@ -358,7 +363,7 @@ function encodeFatSignature(
}

async function rawVerify(
passkeyValidator: WebAuthValidator,
passkeyValidator: WebAuthValidatorTest,
authenticatorData: string,
clientData: string,
b64SignedChallange: string,
Expand All @@ -370,7 +375,7 @@ async function rawVerify(
const rs = unwrapEC2Signature(toBuffer(b64SignedChallange));
const publicKeys = await getPublicKey(publicKeyEs256Bytes);

return await passkeyValidator.rawVerify(hashedData, rs, publicKeys);
return await passkeyValidator.p256Verify(hashedData, rs, publicKeys);
}

async function verifyKeyStorage(
Expand All @@ -390,11 +395,11 @@ function encodeKeyFromHex(hexStrings: [Hex, Hex], domain: string) {
// the same as the ethers: new AbiCoder().encode(["bytes32[2]", "string"], [bytes, domain]);
return encodeAbiParameters(
[
{ name: 'publicKeys', type: 'bytes32[2]' },
{ name: 'domain', type: 'string' },
{ name: "publicKeys", type: "bytes32[2]" },
{ name: "domain", type: "string" },
],
[hexStrings, domain]
)
[hexStrings, domain],
);
}

function encodeKeyFromBytes(bytes: [Uint8Array, Uint8Array], domain: string) {
Expand Down Expand Up @@ -428,8 +433,8 @@ async function validateSignatureTest(
{ name: "clientDataJson", type: "string" },
{ name: "rs", type: "bytes32[2]" },
],
[toHex(authData), sampleClientString, [toHex(rNormalization(generatedSignature.r)), toHex(sNormalization(generatedSignature.s))]]
)
[toHex(authData), sampleClientString, [toHex(rNormalization(generatedSignature.r)), toHex(sNormalization(generatedSignature.s))]],
);
return await passkeyValidator.validateSignature(transactionHash, fatSignature);
}

Expand Down Expand Up @@ -480,7 +485,7 @@ describe("Passkey validation", function () {
const receipt = await fundTx.wait();
expect(receipt.status).to.eq(1, "send funds to proxy account");

return { passKeyModuleContract, sampleDomain, proxyAccountAddress, generatedR1Key, passKeyModuleAddress }
return { passKeyModuleContract, sampleDomain, proxyAccountAddress, generatedR1Key, passKeyModuleAddress };
}

it("should deploy proxy account via factory", async () => {
Expand Down Expand Up @@ -523,16 +528,16 @@ describe("Passkey validation", function () {
], [
toHex(authData),
sampleClientString,
[toHex(normalizeR(generatedSignature.r)), toHex(normalizeS(generatedSignature.s))]
])
[toHex(normalizeR(generatedSignature.r)), toHex(normalizeS(generatedSignature.s))],
]);

const moduleSignature = encodeAbiParameters(
[{ name: "signature", type: "bytes" }, { name: "moduleAddress", type: "address" }, { name: "validatorData", type: "bytes" }],
[fatSignature, passKeyModuleAddress, "0x"]);
return moduleSignature;
},
address: proxyAccountAddress,
secret: wallet.privateKey, //generatedR1Key.privateKey,
secret: wallet.privateKey, // generatedR1Key.privateKey,
}, provider);

const aaTransaction = {
Expand Down Expand Up @@ -653,7 +658,6 @@ describe("Passkey validation", function () {
clientDataJSON: ethersResponse.clientData,
signature: ethersResponse.b64SignedChallenge,
},
{ passkey: publicKeys[0] },
);

const initData = encodeKeyFromHex(publicKeys, "http://localhost:5173");
Expand All @@ -671,14 +675,14 @@ describe("Passkey validation", function () {
// fully expand the raw validation to compare step by step
describe("P256 precompile comparison", () => {
it("should verify passkey", async function () {
const passkeyValidator = await deployValidator(wallet);
const passkeyValidator = await deployP256Tester(wallet);

// 37 bytes
const authenticatorData = "SZYN5YgOjGh0NBcPZHZgW4_krrmihjLHmVzzuoMdl2MFAAAABQ";
const clientData =
"eyJ0eXBlIjoid2ViYXV0aG4uZ2V0IiwiY2hhbGxlbmdlIjoiZFhPM3ctdWdycS00SkdkZUJLNDFsZFk1V2lNd0ZORDkiLCJvcmlnaW4iOiJodHRwOi8vbG9jYWxob3N0OjUxNzMiLCJjcm9zc09yaWdpbiI6ZmFsc2UsIm90aGVyX2tleXNfY2FuX2JlX2FkZGVkX2hlcmUiOiJkbyBub3QgY29tcGFyZSBjbGllbnREYXRhSlNPTiBhZ2FpbnN0IGEgdGVtcGxhdGUuIFNlZSBodHRwczovL2dvby5nbC95YWJQZXgifQ";
const b64SignedChallenge =
"MEUCIQCYrSUCR_QUPAhvRNUVfYiJC2JlOKuqf4gx7i129n9QxgIgaY19A9vAAObuTQNs5_V9kZFizwRpUFpiRVW_dglpR2A";
const clientData
= "eyJ0eXBlIjoid2ViYXV0aG4uZ2V0IiwiY2hhbGxlbmdlIjoiZFhPM3ctdWdycS00SkdkZUJLNDFsZFk1V2lNd0ZORDkiLCJvcmlnaW4iOiJodHRwOi8vbG9jYWxob3N0OjUxNzMiLCJjcm9zc09yaWdpbiI6ZmFsc2UsIm90aGVyX2tleXNfY2FuX2JlX2FkZGVkX2hlcmUiOiJkbyBub3QgY29tcGFyZSBjbGllbnREYXRhSlNPTiBhZ2FpbnN0IGEgdGVtcGxhdGUuIFNlZSBodHRwczovL2dvby5nbC95YWJQZXgifQ";
const b64SignedChallenge
= "MEUCIQCYrSUCR_QUPAhvRNUVfYiJC2JlOKuqf4gx7i129n9QxgIgaY19A9vAAObuTQNs5_V9kZFizwRpUFpiRVW_dglpR2A";

const verifyMessage = await rawVerify(
passkeyValidator,
Expand All @@ -691,7 +695,7 @@ describe("Passkey validation", function () {
assert(verifyMessage == true, "valid sig");
});
it("should sign with new data", async function () {
const passkeyValidator = await deployValidator(wallet);
const passkeyValidator = await deployP256Tester(wallet);
// The precompile expects the fully hashed data
const preHashedData = await toHash(
concat([toBuffer(ethersResponse.authenticatorData), await toHash(toBuffer(ethersResponse.clientData))]),
Expand All @@ -718,7 +722,7 @@ describe("Passkey validation", function () {
[generatedSignature.r, generatedSignature.s],
[generatedX, generatedY],
);
const onChainGeneratedVerified = await passkeyValidator.rawVerify(
const onChainGeneratedVerified = await passkeyValidator.p256Verify(
preHashedData,
[generatedSignature.r, generatedSignature.s],
[generatedX, generatedY],
Expand All @@ -728,7 +732,7 @@ describe("Passkey validation", function () {
[recordedR, recordedS],
[recordedX, recordedY],
);
const onChainRecordedVerified = await passkeyValidator.rawVerify(
const onChainRecordedVerified = await passkeyValidator.p256Verify(
preHashedData,
[recordedR, recordedS],
[recordedX, recordedY],
Expand All @@ -741,7 +745,7 @@ describe("Passkey validation", function () {
});

it("should verify other test passkey data", async function () {
const passkeyValidator = await deployValidator(wallet);
const passkeyValidator = await deployP256Tester(wallet);

const verifyMessage = await rawVerify(
passkeyValidator,
Expand All @@ -755,10 +759,10 @@ describe("Passkey validation", function () {
});

it("should fail when signature is bad", async function () {
const passkeyValidator = await deployValidator(wallet);
const passkeyValidator = await deployP256Tester(wallet);

const b64SignedChallenge =
"MEUCIQCYrSUCR_QUPAhvRNUVfYiJC2JlOKuqf4gx7i129n9QxgIgaY19A9vAAObuTQNs5_V9kZFizwRpUFpiRVW_dglpR2A";
const b64SignedChallenge
= "MEUCIQCYrSUCR_QUPAhvRNUVfYiJC2JlOKuqf4gx7i129n9QxgIgaY19A9vAAObuTQNs5_V9kZFizwRpUFpiRVW_dglpR2A";
const verifyMessage = await rawVerify(
passkeyValidator,
ethersResponse.authenticatorData,
Expand Down Expand Up @@ -899,10 +903,10 @@ describe("Passkey validation", function () {
const partialClientObject = {
challenge: "jBBiiOGt1aSBy1WAuRGxqU7YzRM5oWpMA9g8MKydjPI",
};
const duplicatedClientString =
JSON.stringify(sampleClientObject).slice(0, -1) +
"," +
JSON.stringify(partialClientObject).slice(1);
const duplicatedClientString
= JSON.stringify(sampleClientObject).slice(0, -1)
+ ","
+ JSON.stringify(partialClientObject).slice(1);
const authData = toBuffer(ethersResponse.authenticatorData);
const transactionHash = Buffer.from(sampleClientObject.challenge, "base64url");
const isValidSignature = await validateSignatureTest(
Expand Down

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