index.js

let verifyAuthenticatorAttestationResponse = (webAuthnResponse) => {
    let attestationBuffer = base64url.toBuffer(webAuthnResponse.response.attestationObject);
    let ctapMakeCredResp  = cbor.decodeAllSync(attestationBuffer)[0];

    let response = {'verified': false};
    if(ctapMakeCredResp.fmt === 'fido-u2f') {
        let authrDataStruct = parseMakeCredAuthData(ctapMakeCredResp.authData);

        if(!(authrDataStruct.flags & U2F_USER_PRESENTED))
            throw new Error('User was NOT presented durring authentication!');

        let clientDataHash  = hash(base64url.toBuffer(webAuthnResponse.response.clientDataJSON))
        let reservedByte    = Buffer.from([0x00]);
        let publicKey       = COSEECDHAtoPKCS(authrDataStruct.COSEPublicKey)
        let signatureBase   = Buffer.concat([reservedByte, authrDataStruct.rpIdHash, clientDataHash, authrDataStruct.credID, publicKey]);

        let PEMCertificate = ASN1toPEM(ctapMakeCredResp.attStmt.x5c[0]);
        let signature      = ctapMakeCredResp.attStmt.sig;

        response.verified = verifySignature(signature, signatureBase, PEMCertificate)

        if(response.verified) {
            response.authrInfo = {
                fmt: 'fido-u2f',
                publicKey: base64url.encode(publicKey),
                counter: authrDataStruct.counter,
                credID: base64url.encode(authrDataStruct.credID)
            }
        }
    }

    return response
}