Home Programming News How KAYAK lowered sign up time by 50% and improved safety with passkeys — Google for Builders

How KAYAK lowered sign up time by 50% and improved safety with passkeys — Google for Builders

How KAYAK lowered sign up time by 50% and improved safety with passkeys — Google for Builders


Posted by Kateryna Semenova, Developer Relations Engineer, Android


KAYAK is without doubt one of the world’s main journey search engines like google and yahoo that helps customers discover the perfect offers on flights, motels, and rental automobiles. In 2023, KAYAK built-in passkeys – a brand new sort of passwordless authentication – into its Android and internet apps. In consequence, KAYAK lowered the common time it takes their customers to sign-up and sign-in by 50%, and likewise noticed a lower in help tickets.

This case research explains KAYAK’s implementation on Android with Credential Supervisor API and RxJava. You should use this case research as a mannequin for implementing Credential Supervisor to enhance safety and person expertise in your personal apps.

If you’d like a fast abstract, take a look at the companion video on YouTube.


Like most companies, KAYAK has relied on passwords up to now to authenticate customers. Passwords are a legal responsibility for each customers and companies alike: they’re typically weak, reused, guessed, phished, leaked, or hacked.

“Providing password authentication comes with loads of effort and threat for the enterprise. Attackers are always attempting to brute power accounts whereas not all customers perceive the necessity for sturdy passwords. Nevertheless, even sturdy passwords aren’t totally safe and may nonetheless be phished.” – Matthias Keller, Chief Scientist and SVP, Expertise at KAYAK

To make authentication safer, KAYAK despatched “magic hyperlinks” through e-mail. Whereas useful from a safety standpoint, this further step launched extra person friction by requiring customers to change to a special app to finish the login course of. Further measures wanted to be launched to mitigate the chance of phishing assaults.


KAYAK’s Android app now makes use of passkeys for a safer, user-friendly, and sooner authentication expertise. Passkeys are distinctive, safe tokens which can be saved on the person’s system and might be synchronized throughout a number of gadgets. Customers can sign up to KAYAK with a passkey by merely utilizing their current system’s display screen lock, making it easier and safer than coming into a password.

“We have added passkeys help to our Android app in order that extra customers can use passkeys as a substitute of passwords. Inside that work, we additionally changed our outdated Smartlock API implementation with the Register with Google supported by Credential Supervisor API. Now, customers are in a position to enroll and sign up to KAYAK with passkeys twice as quick as with an e-mail hyperlink, which additionally improves the completion charge” – Matthias Keller, Chief Scientist and SVP, Expertise at KAYAK

Credential Supervisor API integration

To combine passkeys on Android, KAYAK used the Credential Supervisor API. Credential Supervisor is a Jetpack library that unifies passkey help beginning with Android 9 (API stage 28) and help for conventional sign-in strategies resembling passwords and federated authentication right into a single person interface and API.

Image of Credential Manager's passkey creation screen.

Determine 1: Credential Supervisor’s passkey creation screens.

Designing a strong authentication circulation for apps is essential to make sure safety and a reliable person expertise. The next diagram demonstrates how KAYAK built-in passkeys into their registration and authentication flows:

Flow diagram of KAYAK's registration and authentication processes

Determine 2:KAYAK’s diagram exhibiting their registration and authentication flows.

At registration time, customers are given the chance to create a passkey. As soon as registered, customers can sign up utilizing their passkey, Register with Google, or password. Since Credential Supervisor launches the UI routinely, watch out to not introduce sudden wait occasions, resembling community calls. All the time fetch a one-time problem and different passkeys configuration (resembling RP ID) initially of any app session.

Whereas the KAYAK workforce is now closely invested in coroutines, their preliminary integration used RxJava to combine with the Credential Supervisor API. They wrapped Credential Supervisor calls into RxJava as follows:

override enjoyable createCredential(request: CreateCredentialRequest, exercise: Exercise): Single<CreateCredentialResponse> {
return Single.create { emitter ->

request = request,
exercise = exercise,
cancellationSignal = null,
executor = Executors.newSingleThreadExecutor(),
callback = object : CredentialManagerCallback<CreateCredentialResponse, CreateCredentialException> {
override enjoyable onResult(end result: CreateCredentialResponse) {
emitter.onSuccess(end result)

override enjoyable onError(e: CreateCredentialException) {

This instance defines a Kotlin operate referred to as createCredential() that returns a credential from the person as an RxJava Single of sort CreateCredentialResponse. The createCredential() operate encapsulates the asynchronous strategy of credential registration in a reactive programming fashion utilizing the RxJava Single class.

For a Kotlin implementation of this course of utilizing coroutines, learn the Register your person with Credential Supervisor information.

New person registration sign-up circulation

This instance demonstrates the method KAYAK used to register a brand new credential, right here Credential Supervisor was wrapped in Rx primitives.

.getClientParams(username = )
.flatMap { response ->

.flatMap { request ->

request = request,
exercise = exercise
.flatMap {

{ },
{ }

Rx allowed KAYAK to supply extra complicated pipelines that may contain a number of interactions with Credential Supervisor.

Present person sign-in

KAYAK used the next steps to launch the sign-in circulation. The method launches a backside sheet UI component, permitting the person to log in utilizing a Google ID and an current passkey or saved password.

Image of bottom sheet for passkey authentication

Determine 3:Backside sheet for passkey authentication.

Builders ought to comply with these steps when establishing a sign-in circulation:

  1. Because the backside sheet is launched routinely, watch out to not introduce sudden wait occasions within the UI, resembling community calls. All the time fetch a one-time problem and different passkeys configuration (resembling RP ID) initially of any app session.
  2. When providing Google sign-in through Credential Supervisor API, your code ought to initially search for Google accounts which have already been used with the app. To deal with this, name the API with the setFilterByAuthorizedAccounts parameter set to true.
  3. If the end result returns a listing of obtainable credentials, the app exhibits the underside sheet authentication UI to the person.
  4. If a NoCredentialException seems, no credentials have been discovered: No Google accounts, no passkeys, and no saved passwords. At this level, your app ought to name the API once more and set setFilterByAuthorizedAccounts to false to provoke the Join with Google circulation.
  5. Course of the credential returned from Credential Supervisor.
Single.fromSupplier<GetPublicKeyCredentialOption> {
.flatMap { response ->

.map { publicKeyCredentialOption ->

.flatMap { request ->

request = request,
exercise = exercise
.onErrorResumeNext { throwable ->

if (throwable is NoCredentialException) {
return@onErrorResumeNext credentialManagerRepository.getCredential(
request = GetCredentialRequest(),
exercise = exercise
.flatMapCompletable {



“As soon as the Credential Supervisor API is mostly carried out, it is extremely straightforward so as to add different authentication strategies. Including Google One-Faucet Signal In was nearly zero work after including passkeys.” – Matthias Keller

To study extra, comply with the information on how you can Combine Credentials Supervisor API and how you can Combine Credential Supervisor with Register with Google.

UX concerns

A number of the main person expertise concerns KAYAK confronted when switching to passkeys included whether or not customers ought to be capable of delete passkeys or create multiple passkey.

Our UX information for passkeys recommends that you’ve got an choice to revoke a passkey, and that you make sure that the person doesn’t create duplicate passkeys for a similar username in the identical password supervisor.

Image of KAYAK's UI for passkey management

Determine 4:KAYAK’s UI for passkey administration.

To forestall registration of a number of credentials for a similar account, KAYAK used the excludeCredentials property that lists credentials already registered for the person. The next instance demonstrates how you can create new credentials on Android with out creating duplicates:

enjoyable WebAuthnClientParamsResponse.toCreateCredentialRequest(): String {
val credentialRequest = WebAuthnCreateCredentialRequest(
problem = this.problem!!.asSafeBase64,
relayingParty = this.relayingParty!!,
pubKeyCredParams = this.pubKeyCredParams!!,
userEntity = WebAuthnUserEntity(
id = this.userEntity!!.id.asSafeBase64,
identify = this.userEntity.identify,
displayName = this.userEntity.displayName
authenticatorSelection = WebAuthnAuthenticatorSelection(
authenticatorAttachment = "platform",
residentKey = "most popular"

excludeCredentials = this.allowedCredentials!!.map { it.copy(id = it.id.asSafeBase64) },
return GsonBuilder().disableHtmlEscaping().create().toJson(credentialRequest)

And that is how KAYAK carried out excludeCredentials performance for his or her Net implementation.

var registrationOptions = {
'publicKey': {
'problem': self.base64ToArrayBuffer(knowledge.problem),
'rp': knowledge.rp,
'person': {
'id': new TextEncoder().encode(knowledge.person.id),
'identify': knowledge.person.identify,
'displayName': knowledge.person.displayName
'pubKeyCredParams': knowledge.pubKeyCredParams,
'authenticatorSelection': {
'residentKey': 'required'

if (knowledge.allowCredentials && knowledge.allowCredentials.size > 0) {
var excludeCredentials = [];
for (var i = 0; i < knowledge.allowCredentials.size; i++) {
'id': self.base64ToArrayBuffer(knowledge.allowCredentials[i].id),
'sort': knowledge.allowCredentials[i].sort
registrationOptions.publicKey.excludeCredentials = excludeCredentials;


Server-side implementation

The server-side half is a vital part of an authentication answer. KAYAK added passkey capabilities to their current authentication backend by using WebAuthn4J, an open supply Java library.

KAYAK broke down the server-side course of into the next steps:

  1. The shopper requests parameters wanted to create or use a passkey from the server. This consists of the problem, the supported encryption algorithm, the relying celebration ID, and associated gadgets. If the shopper already has a person e-mail deal with, the parameters will embrace the person object for registration, and a listing of passkeys if any exist.
  2. The shopper runs browser or app flows to begin passkey registration or sign-in.
  3. The shopper sends retrieved credential data to the server. This consists of shopper ID, authenticator knowledge, shopper knowledge, and different associated gadgets. This data is required to create an account or confirm a sign-in.

When KAYAK labored on this venture, no third-party merchandise supported passkeys. Nevertheless, many sources are actually out there for making a passkey server, together with documentation and library examples.


Since integrating passkeys, KAYAK has seen a major improve in person satisfaction. Customers have reported that they discover passkeys to be a lot simpler to make use of than passwords, as they don’t require customers to recollect or sort in a protracted, complicated string of characters. KAYAK lowered the common time it takes their customers to sign-up and sign-in by 50%, have seen a lower in help tickets associated to forgotten passwords, and have made their system safer by lowering their publicity to password-based assaults. Thanks to those enhancements, ​​KAYAK plans to remove password-based authentication of their app by the tip of 2023.

“Passkeys make creating an account lightning quick by eradicating the necessity for password creation or navigating to a separate app to get a hyperlink or code. As a bonus, implementing the brand new Credential Supervisor library additionally lowered technical debt in our code base by placing passkeys, passwords and Google sign-in all into one new fashionable UI. Certainly, customers are in a position to enroll and sign up to KAYAK with passkeys twice as quick as with an e-mail hyperlink, which additionally improves the completion charge.” – Matthias Keller


Passkeys are a brand new and modern authentication answer that gives important advantages over conventional passwords. KAYAK is a superb instance of how a corporation can enhance the safety and usefulness of its authentication course of by integrating passkeys. In case you are searching for a safer and user-friendly authentication expertise, we encourage you to think about using passkeys with Android’s Credential Supervisor API.



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