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fidotools.js
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fidotools.js
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(function(global) {
var GLOBALPOLICY = {
/*
* Allowed attestation types
*/
allowedAttestationTypes: [ "Basic", "None", "AttCA", "Self" ],
/*
* Supported attestation formats
*/
supportedAttestationFormats: [ "fido-u2f", "packed", "none", "tpm", "android-safetynet", "android-key", "apple" ],
/*
* Supported packed attestation signature algorithms
*/
// -7 ECDSA256
// -8 ALG_SIGN_ED25519_EDDSA_SHA256_RAW
// -35 ALG_SIGN_SECP384R1_ECDSA_SHA384_RAW
// -36 ALG_SIGN_SECP521R1_ECDSA_SHA512_RAW
// -37 ALG_SIGN_RSASSA_PSS_SHA256_RAW
// -38 ALG_SIGN_RSASSA_PSS_SHA384_RAW
// -39 ALG_SIGN_RSASSA_PSS_SHA512_RAW
// -257 ALG_SIGN_RSASSA_PKCSV15_SHA256_RAW
// -258 ALG_SIGN_RSASSA_PKCSV15_SHA384_RAW
// -259 ALG_SIGN_RSASSA_PKCSV15_SHA512_RAW
// -65535 ALG_SIGN_RSASSA_PKCSV15_SHA1_RAW
supportedPackedAttestationAlgorithms: [ -7, -35, -37, -38, -39, -257, -258, -259, -65535 ],
// I tried to do -36 however it seems KJUR does not support P521 for the Signature class
// Same problem for -8
// see: https://kjur.github.io/jsrsasign/api/symbols/KJUR.crypto.Signature.html#constructor
/* Permitted age of android-safetynet attestations in milliseconds. Set to -1 to disable */
androidSafetyNetMaxAttestationAgeMS: 60000
}
/**
* debug loggining within these tools
*/
function debugLog(str) {
console.log(str);
}
/**
* Compares two byte arrays, return true if they contain the same bytes
*/
function baEqual(ba1, ba2) {
var result = false;
if (Array.isArray(ba1) && Array.isArray(ba2)) {
if (ba1.length == ba2.length) {
var result = true;
for (var i = 0; i < ba1.length && result; i++) {
result = (ba1[i] == ba2[i]);
}
}
}
return result;
}
/**
* Utility function to check if all bytes in an array are zero
*/
function bytesZero(ba) {
var result = false;
if (Array.isArray(ba)) {
result = true;
for (var i = 0; i < ba.length && result; i++) {
if (ba[i] != 0x00) {
result = false;
}
}
}
return result;
}
/**
* Extracts the bytes from an array beginning at index start, and continuing until
* index end-1 or the end of the array is reached. Pass -1 for end if you want to
* parse till the end of the array.
*/
function bytesFromArray(o, start, end) {
// o may be a normal array of bytes, or it could be a JSON encoded Uint8Array
var len = o.length;
if (len == null) {
len = Object.keys(o).length;
}
var result = [];
for (var i = start; (end == -1 || i < end) && (i < len); i++) {
result.push(o[i]);
}
return result;
}
/**
* Convert a 4-byte array to a uint assuming big-endian encoding
*
* @param buf
*/
function bytesToUInt32BE(buf) {
var result = 0;
if (buf != null && buf.length == 4) {
result = ((buf[0] & 0xFF) << 24) | ((buf[1] & 0xFF) << 16) | ((buf[2] & 0xFF) << 8) | (buf[3] & 0xFF);
return result;
}
return result;
}
/**
* Uses the ASN1 parser to look for a OID in a PEM x509 cert and return it's value as a hex string
*/
function findCertOIDValueHex(certPEM, oid) {
var result = null;
try {
var x509Cert = new X509();
x509Cert.readCertPEM(certPEM);
var oidInfo = x509Cert.getExtInfo(oid);
debugLog("The oidInfo is: " + JSON.stringify(oidInfo));
if (oidInfo != null) {
result = ASN1HEX.getV(pemtohex(certPEM), oidInfo.vidx);
} else {
debugLog("Did not find OID: " + oid + " in cert: " + certPEM);
}
} catch(e) {
result = null;
debugLog("Error parsing cert and looking for oid: " + oid);
debugLog(e);
}
return result;
}
/**
* Returns the bytes of a sha1 message digest of either a string or byte array
* This is used when building the signature base string to verify
* registration data.
*/
function sha1(data) {
var md = new KJUR.crypto.MessageDigest({
alg : "sha1",
prov : "cryptojs"
});
if (Array.isArray(data)) {
md.updateHex(BAtohex(data));
} else {
md.updateString(data);
}
return b64toBA(hex2b64(md.digest()));
}
/**
* Returns the bytes of a sha256 message digest of either a string or byte array
* This is used when building the signature base string to verify
* registration data.
*/
function sha256(data) {
var md = new KJUR.crypto.MessageDigest({
alg : "sha256",
prov : "cryptojs"
});
if (Array.isArray(data)) {
md.updateHex(BAtohex(data));
} else {
md.updateString(data);
}
return b64toBA(hex2b64(md.digest()));
}
/**
* Returns the bytes of a sha384 message digest of either a string or byte array
* This is used when building the signature base string to verify
* registration data.
*/
function sha384(data) {
var md = new KJUR.crypto.MessageDigest({
alg : "sha384",
prov : "cryptojs"
});
if (Array.isArray(data)) {
md.updateHex(BAtohex(data));
} else {
md.updateString(data);
}
return b64toBA(hex2b64(md.digest()));
}
/**
* Returns the bytes of a sha512 message digest of either a string or byte array
* This is used when building the signature base string to verify
* registration data.
*/
function sha512(data) {
var md = new KJUR.crypto.MessageDigest({
alg : "sha512",
prov : "cryptojs"
});
if (Array.isArray(data)) {
md.updateHex(BAtohex(data));
} else {
md.updateString(data);
}
return b64toBA(hex2b64(md.digest()));
}
/**
* Converts the bytes of an asn1-encoded X509 ceritificate or raw public key
* into a PEM-encoded cert string
*/
function certToPEM(cert) {
var keyType = "CERTIFICATE";
asn1key = cert;
if (cert != null && cert.length == 65 && cert[0] == 0x04) {
// this is a raw public key - prefix with ASN1 metadata
// SEQUENCE {
// SEQUENCE {
// OBJECTIDENTIFIER 1.2.840.10045.2.1 (ecPublicKey)
// OBJECTIDENTIFIER 1.2.840.10045.3.1.7 (P-256)
// }
// BITSTRING <raw public key>
// }
// We just need to prefix it with constant 26 bytes of metadata
asn1key = b64toBA(hextob64("3059301306072a8648ce3d020106082a8648ce3d030107034200"));
Array.prototype.push.apply(asn1key, cert);
keyType = "PUBLIC KEY";
}
var result = "-----BEGIN " + keyType + "-----\n";
var b64cert = hextob64(BAtohex(asn1key));
for (; b64cert.length > 64; b64cert = b64cert.slice(64)) {
result += b64cert.slice(0, 64) + "\n";
}
if (b64cert.length > 0) {
result += b64cert + "\n";
}
result += "-----END " + keyType + "-----\n";
return result;
}
/**
* Performs signature validation as needed for FIDO registration and authenticate transactions.
*
* @param sigBase -
* signature base string bytes composed from the registration
* response or sign response
* @param cert -
* either an array of bytes of either the x509 attestation certificate
* from the registration data or the public key (for verifying sign responses),
* OR the JSON object of the COSE encoded public key (used for FIDO2
* signature validation).
* @param sig -
* bytes of the signature from the registration data or sign response
* @param alg -
* The COSE algorithm identifier. Can be null in which case ECDSA will be assumed.
*
* @returns true if the signature verified, false otherwise
*/
function verifyFIDOSignature(sigBase, cert, sig, alg) {
var result = false;
// default to ECDSA
if (alg == null) {
alg = -7;
}
var algMap = {
"-7" : "SHA256withECDSA",
"-35" : "SHA384withECDSA",
"-36" : "SHA512withECDSA",
"-37" : "SHA256withRSAandMGF1",
"-38" : "SHA384withRSAandMGF1",
"-39" : "SHA512withRSAandMGF1",
"-257" : "SHA256withRSA",
"-258" : "SHA384withRSA",
"-259" : "SHA512withRSA",
"-65535" : "SHA1withRSA"
};
var algStr = algMap['' + alg];
if (algStr != null) {
var verifier = new KJUR.crypto.Signature({
"alg" : algStr
});
// find out what kind of public key validation material we have
if (Array.isArray(cert)) {
// x509 cert bytes, or EC public key bytes, as typically used by
// FIDO-U2F
verifier.init(certToPEM(cert));
} else {
// assume COSE key format
verifier.init(coseKeyToPublicKey(cert));
}
verifier.updateHex(BAtohex(sigBase));
// debugLog("BEFORE: " + result);
result = verifier.verify(BAtohex(sig));
// debugLog("AFTER: " + result);
} else {
debugLog("Unsupported algorithm in verifyFIDOSignature: " + alg);
}
if (!result) {
// some extra debugging to try figure this out later
debugLog("verifyFIDOSignature failed: var sigBase="
+ JSON.stringify(sigBase) + "; var cert="
+ JSON.stringify(cert) + "; var sig=" + JSON.stringify(sig)
+ "; var alg=" + alg + ";");
}
return result;
}
/**
* Build a human-readable string from the aaguid bytes
*/
function aaguidBytesToUUID(b) {
var result = null;
if (b != null && b.length == 16) {
var s = BAtohex(b).toUpperCase();
result = s.substring(0,8).concat("-",s.substring(8,12),"-",s.substring(12,16),"-",s.substring(16,20),"-",s.substring(20,s.length));
}
return result;
}
function coseKeyToECDSA256PublicKeyBytes(k) {
var result = { "error": "unknown error", "keyBytes": null };
if (k != null) {
// see https://tools.ietf.org/html/rfc8152 for all these magic numbers
var kty = k["1"];
var alg = k["3"];
var crv = k["-1"];
// validate the key type is EC2
if (kty == 2) {
// validate the alg is ECDSA256
if (alg == -7) {
// validate the curve is P256
if (crv == 1) {
// obtain x and y coordinates for EC - these should each be 32 bytes long
var xCoordinateBytes = bytesFromArray(k["-2"], 0, -1);
var yCoordinateBytes = bytesFromArray(k["-3"], 0, -1);
if (xCoordinateBytes.length == 32 && yCoordinateBytes.length == 32) {
// seems ok build publicKey
result["error"] = null;
result["keyBytes"] = [ 0x04 ].concat(xCoordinateBytes, yCoordinateBytes);
} else {
result["error"] = "The size of the x or y co-ordinates is wrong";
}
} else {
result["error"] = "The crv of the credential public key is invalid";
}
} else {
result["error"] = "The alg of the credential public key is invalid";
}
} else {
result["error"] = "The key type of the credential public key is invalid";
}
} else {
result["error"] = "Credential public key is null";
}
return result;
}
function ECDSA256PublicKeyBytesToCoseKey(b) {
var result = { "error": "unknown error", "coseKey": null };
if (b != null && b.length == 65) {
if (b[0] == 0x04) {
var xCoordinateBytes = bytesFromArray(b, 1, 33);
var yCoordinateBytes = bytesFromArray(b, 33, -1);
// see https://tools.ietf.org/html/rfc8152 for all these magic numbers
// set kty, alg and crv statically
result["coseKey"] = { "1": 2, "3": -7, "-1": 1 };
// now the bytes from the x and y co-ordinates
result["coseKey"]["-2"] = new Uint8Array(xCoordinateBytes);
result["coseKey"]["-3"] = new Uint8Array(yCoordinateBytes);
result["error"] = null;
} else {
result["error"] = "The provided elyptic curve public key bytes do not start with 0x04";
}
} else {
result["error"] = "The provided elyptic curve public key bytes are of invalid length";
}
return result;
}
// see table 6.4 of https://trustedcomputinggroup.org/wp-content/uploads/TCG_TPM2_r1p59_Part2_Structures_pub.pdf
function tpmECCCurvetoCoseCurve(tpmCurveID) {
// default is no match
var result = -1;
if (tpmCurveID == 3) {
result = 1;
} else if (tpmCurveID == 4) {
result = 2;
} else if (tpmCurveID == 5) {
result = 3;
} else {
// we don't support it
result = -1;
}
return result;
}
function coseKeyToPublicKey(k) {
var result = null;
if (k != null) {
// see https://tools.ietf.org/html/rfc8152
// and https://www.iana.org/assignments/cose/cose.xhtml
var kty = k["1"];
var alg = k["3"];
if (kty == 1) {
// EdDSA key type
validEDAlgs = [ -8 ];
if (validEDAlgs.indexOf(alg) >= 0) {
var crvMap = {
"6" : "Ed25519",
"7" : "Ed448"
};
var crv = crvMap['' + k["-1"]];
if (crv != null) {
debugLog("No support for EdDSA keys");
} else {
debugLog("Invalid crv: " + k["-1"] + " for ED key type");
}
} else {
debugLog("Invalid alg: " + alg + " for ED key type");
}
} else if (kty == 2) {
// EC key type
validECAlgs = [ -7, -35, -36 ];
if (validECAlgs.indexOf(alg) >= 0) {
var crvMap = {
"1" : "P-256",
"2" : "P-384",
"3" : "P-521" // this is not a typo. It is 521
};
var crv = crvMap['' + k["-1"]];
if (crv != null) {
// ECDSA
var xCoordinate = bytesFromArray(k["-2"], 0, -1);
var yCoordinate = bytesFromArray(k["-3"], 0, -1);
if (xCoordinate != null && xCoordinate.length > 0
&& yCoordinate != null && yCoordinate.length > 0) {
result = KEYUTIL.getKey({
"kty" : "EC",
"crv" : crv,
"x" : hextob64(BAtohex(xCoordinate)),
"y" : hextob64(BAtohex(yCoordinate))
});
} else {
debugLog("Invalid x or y co-ordinates for EC key type");
}
} else {
debugLog("Invalid crv: " + k["-1"] + " for EC key type");
}
} else {
debugLog("Invalid alg: " + alg + " for EC key type");
}
} else if (kty == 3) {
// RSA key type
validRSAAlgs = [ -37, -38, -39, -257, -258, -259, -65535 ];
if (validRSAAlgs.indexOf(alg) >= 0) {
var n = bytesFromArray(k["-1"], 0, -1);
var e = bytesFromArray(k["-2"], 0, -1);
if (n != null && n.length > 0 && e != null && e.length > 0) {
result = KEYUTIL.getKey({
"kty" : "RSA",
"n" : hextob64(BAtohex(n)),
"e" : hextob64(BAtohex(e))
});
} else {
debugLog("Invalid n or e values for RSA key type");
}
} else {
debugLog("Invalid alg: " + alg + " for RSA key type");
}
} else {
debugLog("Unsupported key type: " + kty);
}
}
return result;
}
function padToEvenNumberOfHexDigits(s) {
let result = s;
if (s.length%2 == 1) {
result = '0'+s;
}
return result;
}
function publicKeyToCOSEKey(pk) {
// should be one of RSAKey, KJUR.crypto.ECDSA as these are all we support
let result = null;
try {
if (pk instanceof RSAKey) {
result = {
"1": 3,
"3": -257,
"-1": b64toBA(hextob64(padToEvenNumberOfHexDigits(pk.n.toString(16)))),
"-2": b64toBA(hextob64(padToEvenNumberOfHexDigits(pk.e.toString(16))))
};
} else if (pk instanceof KJUR.crypto.ECDSA) {
// see table 5: https://datatracker.ietf.org/doc/html/rfc8152#section-8.1
const curveNameToAlgID = {
"secp256r1": -7,
"secp384r1": -35,
"secp521r1": -36
};
let alg = (pk.curveName == null ? null : curveNameToAlgID[pk.curveName]);
if (alg == null) {
throw "Unrecognized ECDSA curve: " + pk.curveName;
}
// see Table 22: https://datatracker.ietf.org/doc/html/rfc8152#section-13.1
const curveNameToCurveKey = {
"secp256r1": 1,
"secp384r1": 2,
"secp521r1": 3
};
let keyID = curveNameToCurveKey[pk.curveName];
if (keyID == null) {
throw "Unrecognized ECDSA curve: " + pk.curveName;
}
// these keys come from Table 19: https://datatracker.ietf.org/doc/html/rfc8152#section-12.4.1
result = {
"1": 2,
"3": alg,
"-1": keyID,
"-2": b64toBA(hextob64(pk.getPublicKeyXYHex().x)),
"-3": b64toBA(hextob64(pk.getPublicKeyXYHex().y))
};
} else {
throw "Unknown key type";
}
} catch(e) {
console.log("Unsupported public key object: " + pk + " error: " + e);
}
return result;
}
function unpackAuthData(authDataBytes) {
debugLog("unpackAuthData enter");
var result = {
"status": false,
"rawBytes": null,
"rpIdHashBytes": null,
"flags": 0,
"counter": 0,
"attestedCredData": null,
"extensions": null
};
result["rawBytes"] = authDataBytes;
if (authDataBytes != null && authDataBytes.length >= 37) {
result["rpIdHashBytes"] = bytesFromArray(authDataBytes, 0, 32);
result["flags"] = authDataBytes[32];
result["counter"] = bytesToUInt32BE(bytesFromArray(authDataBytes, 33, 37));
var nextByteIndex = 37;
// check flags to see if there is attested cred data and/or extensions
// bit 6 of flags - Indicates whether the authenticator added attested credential data.
if (result["flags"] & 0x40) {
result["attestedCredData"] = {};
// are there enough bytes to read aaguid?
if (authDataBytes.length >= (nextByteIndex + 16)) {
result["attestedCredData"]["aaguid"] = bytesFromArray(authDataBytes, nextByteIndex, (nextByteIndex+16));
nextByteIndex += 16;
// are there enough bytes for credentialIdLength?
if (authDataBytes.length >= (nextByteIndex + 2)) {
var credentialIdLengthBytes = bytesFromArray(authDataBytes, nextByteIndex, (nextByteIndex+2));
nextByteIndex += 2;
var credentialIdLength = credentialIdLengthBytes[0] * 256 + credentialIdLengthBytes[1]
result["attestedCredData"]["credentialIdLength"] = credentialIdLength;
// are there enough bytes for the credentialId?
if (authDataBytes.length >= (nextByteIndex + credentialIdLength)) {
result["attestedCredData"]["credentialId"] = bytesFromArray(authDataBytes, nextByteIndex, (nextByteIndex+credentialIdLength));
nextByteIndex += credentialIdLength;
var remainingBytes = bytesFromArray(authDataBytes, nextByteIndex, -1);
//debugLog("remainingBytes: " + JSON.stringify(remainingBytes));
//
// try CBOR decoding the remaining bytes.
// NOTE: There could be both credentialPublicKey and extensions objects
// so we use this special decodeVariable that Shane wrote to deal with
// remaining bytes.
//
try {
var decodeResult = CBOR.decodeVariable((new Uint8Array(remainingBytes)).buffer);
result["attestedCredData"]["credentialPublicKey"] = decodeResult["decodedObj"];
nextByteIndex += (decodeResult["offset"] == -1 ? remainingBytes.length : decodeResult["offset"]);
} catch (e) {
debugLog("Error CBOR decoding credentialPublicKey: " + e);
nextByteIndex = -1; // to force error checking
}
} else {
debugLog("unPackAuthData encountered authDataBytes not containing enough bytes for credentialId in attested credential data");
}
} else {
debugLog("unPackAuthData encountered authDataBytes not containing enough bytes for credentialIdLength in attested credential data");
}
} else {
debugLog("unPackAuthData encountered authDataBytes not containing enough bytes for aaguid in attested credential data");
}
}
// bit 7 of flags - Indicates whether the authenticator has extensions.
if (nextByteIndex > 0 && result["flags"] & 0x80) {
try {
result["extensions"] = CBOR.decode((new Uint8Array(bytesFromArray(authDataBytes, nextByteIndex, -1))).buffer);
// must have worked
nextByteIndex = authDataBytes.length;
} catch (e) {
debugLog("Error CBOR decoding extensions");
}
}
// we should be done - make sure we processed all the bytes
if (nextByteIndex == authDataBytes.length) {
result["status"] = true;
} else {
debugLog("Remaining bytes in unPackAuthData. nextByteIndex: " + nextByteIndex + " authDataBytes.length: " + authDataBytes.length);
}
} else {
debugLog("unPackAuthData encountered authDataBytes not at least 37 bytes long. Actual length: " + authDataBytes.length);
}
debugLog("unpackAuthData returning: " + JSON.stringify(result));
return result;
}
/**
* Check that the fmt is one registered by IANA registry of WebAuthn-Registries
*
* @param fmt
*/
function validateAttestationStatementFormat(fmt) {
// based on policy (and capabilities)
return (fmt != null && GLOBALPOLICY["supportedAttestationFormats"]
.indexOf(fmt) >= 0);
}
function validateAttestationStatementNone(attestationObject, unpackedAuthData,
clientDataHashBytes) {
debugLog("validateAttestationStatementNone enter");
var result = {
"success" : false,
"attestationType" : null,
"attestationTrustPath" : null,
"aaguid" : null,
"error" : "Unknown Error validating Attestation Statement"
};
if (unpackedAuthData["attestedCredData"] != null) {
var attestedCredData = unpackedAuthData["attestedCredData"];
var aaguid = attestedCredData["aaguid"];
if (aaguid != null) {
var credentialId = attestedCredData["credentialId"];
if (credentialId != null) {
var credentialPublicKey = attestedCredData["credentialPublicKey"];
if (credentialPublicKey != null) {
// if all checks ok, fill in result
result["success"] = true;
result["attestationType"] = "None";
result["attestationTrustPath"] = [];
result["aaguid"] = aaguid;
result["credentialId"] = credentialId;
result["credentialPublicKey"] = credentialPublicKey;
result["format"] = attestationObject["fmt"];
result["error"] = null;
} else {
result["error"] = "attested credential data does not contain credentialPublicKey";
}
} else {
result["error"] = "attested credential data does not contain credentialId";
}
} else {
result["error"] = "attested credential data does not contain aaguid";
}
} else {
result["error"] = "authData does not contain attested credential data";
}
return result;
}
// s is a string similar to one of these:
// "/C=SE/O=Yubico AB/OU=Authenticator Attestation/CN=Yubico U2F EE Serial 1955003842"
// "/C=KR/ST=Seoul-Si/L=Gangnam-Gu/O=eWBM Co., Ltd./OU=Authenticator Attestation/CN=eWBM FIDO2 Certificate/[email protected]"
function unpackSubjectDN(s) {
var result = {};
if (s != null) {
var pieces = s.split('/');
for (var i = 0; i < pieces.length; i++) {
var nev = pieces[i].split(/=(.*)/);
if (nev != null && nev.length == 3) {
// ignore empty string at end of array
// make sure we have consistent (upper case) keys
result[nev[0].toUpperCase()] = nev[1];
}
}
}
return result;
}
function verifyPackedAttestationCertificateRequirements(certBytes) {
var result = true;
debugLog("verifyPackedAttestationCertificateRequirements enter");
// https://www.w3.org/TR/webauthn/#packed-attestation-cert-requirements
try {
var x509Cert = new X509();
x509Cert.readCertHex(BAtohex(certBytes));
// SHANE
debugLog("The attestation certificate is:");
debugLog(certToPEM(certBytes));
// check cert version
result = (x509Cert.getVersion() == 3);
if (!result) {
debugLog("cert version was not 3: " + x509Cert.getVersion());
}
// check subject DN
if (result) {
var subjectString = x509Cert.getSubjectString();
var subjectPieces = unpackSubjectDN(subjectString);
if ("C" in subjectPieces && "O" in subjectPieces && "OU" in subjectPieces && "CN" in subjectPieces) {
debugLog("Subject DN fields found. Country: " + subjectPieces["C"] + " Vendor: "
+ subjectPieces["O"] + " OU: " + subjectPieces["OU"]
+ " CN: " + subjectPieces["CN"]);
// really should do further validation of "C" in particular
// validate OU
if (result) {
if (subjectPieces["OU"] != "Authenticator Attestation") {
debugLog("Attestation certificate subject DN is not the literal string: 'Authenticator Attestation'");
result = false;
}
}
} else {
result = false;
}
if (!result) {
debugLog("subject DN does not contain required fields: "
+ subjectString);
}
}
// check for aaguid in attestation cert
if (result) {
// how should I know this - let's just say "false" until told
// otherwise. The eWMB attestation cert is such an example.
var isAttestationRootCertUsedForMultipleModels = false;
var oidInfo = x509Cert.getExtInfo("1.3.6.1.4.1.45724.1.1.4");
if (oidInfo != null) {
var aaguid = ASN1HEX.getV(BAtohex(certBytes), oidInfo.vidx);
// 16 bytes is 32 hex chars
if (aaguid != null && aaguid.length == 32) {
if (!oidInfo.critical) {
// ok so far
result = true;
} else {
debugLog("oid marked critical");
result = false;
}
} else {
debugLog("aaguid invalid: " + aaguid);
result = false;
}
} else {
debugLog("oid extension not found - we won't mark this as fatal unless it's required");
if (isAttestationRootCertUsedForMultipleModels) {
debugLog("oid extension not found and apparently it was required");
result = false;
}
}
if (!result) {
debugLog("certificate did not contain valid aaguid OID extenstion");
}
}
// check basic constraints
if (result) {
var basicConstraints = x509Cert.getExtBasicConstraints();
debugLog("************* basicConstraints: " + basicConstraints);
result = (basicConstraints == null || !(basicConstraints["cA"] == true));
if (!result) {
debugLog("CA flagged as true in BasicConstraints");
}
}
// no further checks since AIA and CRL distribution point are optional
} catch (e) {
debugLog("verifyPackedAttestationCertificateRequirements error parsing x509 certificate: "
+ e);
result = false;
}
debugLog("verifyPackedAttestationCertificateRequirements returning: "
+ result);
return result;
}
function verifyTPMAttestationCertificateRequirements(certBytes) {
var result = true;
debugLog("verifyTPMAttestationCertificateRequirements enter");
// https://www.w3.org/TR/webauthn/#tpm-cert-requirements
try {
var x509Cert = new X509();
x509Cert.readCertHex(BAtohex(certBytes));
// check cert version
result = (x509Cert.getVersion() == 3);
if (!result) {
debugLog("cert version was not 3: " + x509Cert.getVersion());
}
// check subject is empty
if (result) {
debugLog("about to call getSubjectHex");
var subjectHex = x509Cert.getSubjectHex();
if (subjectHex == null || subjectHex != "3000") {
result = false;
debugLog("subject DN is not empty: " + subjectString);
}
}
// The Subject Alternative Name extension MUST be set as defined in [TPMv2-EK-Profile] section 3.2.9.
// TODO - finish this
} catch (e) {
debugLog("verifyTPMAttestationCertificateRequirements error parsing x509 certificate: "
+ e);
result = false;
}
debugLog("verifyTPMAttestationCertificateRequirements returning: "
+ result);
return result;
}
/*
* Given the bytes of an x509 attestation certificate, per step 2, sub-bullet 3
* of https://www.w3.org/TR/webauthn/#packed-attestation check if it contains an
* OID "1.3.6.1.4.1.45724.1.1.4" and if it does, that it matches the aaguid from
* the authentication data
*/
function packedAttestationOIDCheck(x5cBytes, unpackedAuthData) {
var result = false;
var oidValueHex = findCertOIDValueHex(certToPEM(x5cBytes),
"1.3.6.1.4.1.45724.1.1.4");
if (oidValueHex != null) {
var aaguidHex = null;
if (unpackedAuthData["attestedCredData"]["aaguid"] != null) {
aaguidHex = BAtohex(unpackedAuthData["attestedCredData"]["aaguid"]);
}
debugLog("oidValueHex: " + oidValueHex + " aaguidHex: " + aaguidHex);
result = (aaguidHex != null && aaguidHex == oidValueHex);
} else {
debugLog("Warning: Did not find OID 1.3.6.1.4.1.45724.1.1.4 in x5cBytes");
// this is apparently ok since it only says to check against aaguid if
// the oid exists
result = true;
}
return result;
}
function tpmAttestationOIDCheck(x5cBytes, unpackedAuthData) {
// this is actually the same as the packed attestation oid check
return packedAttestationOIDCheck(x5cBytes, unpackedAuthData);
}
function validateAttestationStatementFIDOU2F(attestationObject,
unpackedAuthData, clientDataHashBytes) {
debugLog("validateAttestationStatementFIDOU2F enter");
var result = {
"success" : false,
"attestationType" : null,
"attestationTrustPath" : null,
"aaguid" : null,
"error" : "Unknown Error validating Attestation Statement"
};
// see https://www.w3.org/TR/webauthn/#fido-u2f-attestation
var attStmt = attestationObject["attStmt"];
if (attStmt != null) {
// let's validate the attested credential data
if (unpackedAuthData["attestedCredData"] != null) {
var attestedCredData = unpackedAuthData["attestedCredData"];
var aaguid = attestedCredData["aaguid"];
if (aaguid != null) {
if (bytesZero(aaguid)) {
var credentialId = attestedCredData["credentialId"];
if (credentialId != null) {
var credentialPublicKey = attestedCredData["credentialPublicKey"];
if (credentialPublicKey != null) {
// unpack and validate the cose key
// (https://tools.ietf.org/html/rfc8152)
var coseKeyValidationResult = coseKeyToECDSA256PublicKeyBytes(credentialPublicKey);
if (coseKeyValidationResult["keyBytes"] != null) {
/*
* obtain the signature bytes and x509 cert array from the attStmt
*/
var sig = attestationObject["attStmt"]["sig"];
if (sig != null) {
var attStmtSigBytes = bytesFromArray(sig, 0, -1);
var x5c = attestationObject["attStmt"]["x5c"];
if (x5c != null && x5c.length > 0) {
var attStmtx5c = [];
for (var i = 0; i < x5c.length; i++) {
attStmtx5c.push(bytesFromArray(x5c[i], 0, -1));
}
// verification procedure
/*
* part 1 of verification procedure: is to extract
* attStmt CBOR data - that was done before calling
* this method
*/
/*
* part 2 of verification procedure: verify that
* attCert public key is EC with P-256 curve
*/
var attCert = attStmtx5c[0];
var pemAttCert = certToPEM(attCert);
var x509AttCert = new X509();
x509AttCert.readCertPEM(pemAttCert);
var attCertPublicKey = x509AttCert
.getPublicKey();
if (attCertPublicKey.type == "EC"
&& attCertPublicKey
.getShortNISTPCurveName() == "P-256") {
/*
* part 3 of verification procedure: extract
* rpIdHash, credentialId and credential
* public key
*/
var rpidhashBytes = bytesFromArray(
attestationObject["authData"], 0,
32);
/*
* credentialId and credential public key
* have already been parsed above
*/
/*
* part 4 of verification procedure: build publicKeyU2F
*/
publicKeyU2F = coseKeyValidationResult["keyBytes"];
/*
* part 5 of verification procedure: build verificationData
*/
if (clientDataHashBytes != null && clientDataHashBytes.length > 0) {
var verificationData = [ 0x00 ].concat(
rpidhashBytes, clientDataHashBytes,
credentialId, publicKeyU2F);
// finally, let's verify the signature
result.success = verifyFIDOSignature(
verificationData, attCert,
attStmtSigBytes, null);
if (result.success) {