Google Online Security Blog

Protecting your device information with Private Set Membership

October 28, 2021

Posted by Kevin Yeo and Sarvar Patel, Private Computing Team
At Google, keeping you safe online is our top priority, so we continuously build the most advanced privacy-preserving technologies into our products. Over the past few years, we've utilized innovations in cryptographic research to keep your personal information private by design and secure by default. As part of this, we launched Password Checkup, which protects account credentials by notifying you if an entered username and password are known to have been compromised in a prior data breach. Using cryptographic techniques, Password Checkup can do this without revealing your credentials to anyone, including Google. Today, Password Checkup protects users across many platforms including Android, Chrome and Google Password Manager.

Another example is Private Join and Compute, an open source protocol which enables organizations to work together and draw insights from confidential data sets. Two parties are able to encrypt their data sets, join them, and compute statistics over the joint data. By leveraging secure multi-party computation, Private Join and Compute is designed to ensure that the plaintext data sets are concealed from all parties.

In this post, we introduce the next iteration of our research, Private Set Membership, as well as its open-source availability. At a high level, Private Set Membership considers the scenario in which Google holds a database of items, and user devices need to contact Google to check whether a specific item is found in the database. As an example, users may want to check membership of a computer program on a block list consisting of known malicious software before executing the program. Often, the set’s contents and the queried items are sensitive, so we designed Private Set Membership to perform this task while preserving the privacy of our users.

Protecting your device information during enrollment
Beginning in Chrome 94, Private Set Membership will enable Chrome OS devices to complete the enrollment process in a privacy-preserving manner. Device enrollment is an integral part of the out-of-box experience that welcomes you when getting started with a Chrome OS device.

The device enrollment process requires checking membership of device information in encrypted Google databases, including checking if a device is enterprise enrolled or determining if a device was pre-packaged with a license. The correct end state of your Chrome OS device is determined using the results of these membership checks.

During the enrollment process, we protect your Chrome OS devices by ensuring no information ever leaves the device that may be decrypted by anyone else when using Private Set Membership. Google will never learn any device information and devices will not learn any unnecessary information about other devices. To our knowledge, this is the first instance of advanced cryptographic tools being leveraged to protect device information during the enrollment process.

A deeper look at Private Set Membership
Private Set Membership is built upon two cryptographic tools:

Homomorphic encryption is a powerful cryptographic tool that enables computation over encrypted data without the need for decryption. As an example, given the encryptions of values X and Y, homomorphic encryption enables computing the encryption of the sum of X and Y without ever needing to decrypt. This preserves privacy as the data remains concealed during the computation. Private Set Membership is built upon Google’s open source homomorphic encryption library.
Oblivious hashing is a cryptographic technique that enables two parties to jointly compute a hash, H(K, x), where the sender holds the key, K, and the receiver holds the hash input, x. The receiver will obtain the hash, H(K, x), without learning the key K. At the same time, the input x will be hidden from the sender.

Take a look at how Private Set Membership utilizes homomorphic encryption and oblivious hashing to protect data below:

For a deeper look into the technology behind Private Set Membership, you can also access our open source code.

Privacy properties
By using Private Set Membership, the following privacy properties are obtained:

No data leaves the device when checking membership. We designed Private Set Membership using advanced cryptographic techniques to ensure that data never leaves the device in an unencrypted manner when performing membership checks. As a result, the data on your device will be concealed from everyone, including Google.
Devices learn only membership information and nothing else. Private Set Membership was designed to prevent devices from learning any unnecessary information about other devices when querying. For each query, devices learn only the results of the membership check and no other information.

Using Private Set Membership to solve more problems
Private Set Membership is a powerful tool that solves a fundamental problem in a privacy-preserving manner. This is just the beginning of what’s possible using this technology. Private Set Membership can help preserve user privacy across a wide array of applications. For example:

Checking allow or block lists. In this setting, users check membership in an allow or block list to determine whether to proceed with the desired action. Private Set Membership enables this check without any information about the software leaving the device.
Control flows with conditional membership checks. Control flows are a common computer science concept that represent arbitrary computer programs with conditional branching. In many cases, the conditional branches require checking membership of sensitive data to determine the next step of the algorithm. By utilizing Private Set Membership, we enable execution of these algorithms while ensuring data never leaves the user’s device.

We still have a ways to go before Private Set Membership is used for general membership checks by devices. At Google, we are exploring a number of potential use cases to protect your privacy using Private Set Membership. We are excited to continue advancing the state-of-the-art cryptographic research to keep you safe.

Acknowledgements

The work in this post is the result of a collaboration between a large group of current and former Google engineers, research scientists and others including: Amr Aboelkher, Asra Ali, Ghous Amjad, Yves Arrouye, Roland Bock, Xi Chen, Maksim Ivanov, Dennis Kalinichenko, Nirdhar Khazanie, Dawon Lee, Tancrède Lepoint, Lawrence Lui, Pavol Marko, Thiemo Nagel, Mariana Raykova, Aaron Segal, Joon Young Seo, Karn Seth, and Jason Wong.

Pixel 6: Setting a new standard for mobile security

October 27, 2021

Posted by Dave Kleidermacher, Jesse Seed, Brandon Barbello, and Stephan Somogyi, Android, Pixel & Tensor security teams With Pixel 6 and Pixel 6 Pro, we’re launching our most secure Pixel phone yet, with 5 years of security updates and the most layers of hardware security. These new Pixel smartphones take a layered security approach, with innovations spanning across the Google Tensor system on a chip (SoC) hardware to new Pixel-first features in the Android operating system, making it the first Pixel phone with Google security from the silicon all the way to the data center. Multiple dedicated security teams have also worked to ensure that Pixel’s security is provable through transparency and external validation. Secure to the Core Google has put user data protection and transparency at the forefront of hardware security with Google Tensor. Google Tensor’s main processors are Arm-based and utilize TrustZone™ technology. TrustZone is a key part of our security architecture for general secure processing, but the security improvements included in Google Tensor go beyond TrustZone.

Figure 1. Pixel Secure EnvironmentsThe Google Tensor security core is a custom designed security subsystem dedicated to the preservation of user privacy. It's distinct from the application processor, not only logically, but physically, and consists of a dedicated CPU, ROM, one-time-programmable (OTP) memory, crypto engine, internal SRAM, and protected DRAM. For Pixel 6 and 6 Pro, the security core’s primary use cases include protecting user data keys at runtime, hardening secure boot, and interfacing with Titan M2^TM. Your secure hardware is only as good as your secure OS, and we are using Trusty, our open source trusted execution environment. Trusty OS is the secure OS used both in TrustZone and the Google Tensor security core. With Pixel 6 and Pixel 6 Pro your security is enhanced by the new Titan M2^TM, our discrete security chip, fully designed and developed by Google. In this next generation chip, we moved to an in-house designed RISC-V processor, with extra speed and memory, and made it even more resilient to advanced attacks. Titan M2^TM has been tested against the most rigorous standard for vulnerability assessment, AVA_VAN.5, by an independent, accredited evaluation lab. Titan M2™ supports Android Strongbox, which securely generates and stores keys used to protect your PINs and password, and works hand-in-hand with Google Tensor security core to protect user data keys while in use in the SoC. Moving a step higher in the system, Pixel 6 and Pixel 6 Pro ship with Android 12 and a slew of Pixel-first and Pixel-exclusive features. Enhanced Controls We aim to give users better ways to control their data and manage their devices with every release of Android. Starting with Android 12 on Pixel, you can use the new Security hub to manage all your security settings in one place. It helps protect your phone, apps, Google Account, and passwords by giving you a central view of your device’s current configuration. Security hub also provides recommendations to improve your security, helping you decide what settings best meet your needs.

For privacy, we are launching Privacy Dashboard, which will give you a simple and clear timeline view of the apps that have accessed your location, microphone and camera in the last 24 hours. If you notice apps that are accessing more data than you expected, the dashboard provides a path to controls to change those permissions on the fly.

To provide additional transparency, new indicators in Pixel’s status bar will show you when your camera and mic are being accessed by apps. If you want to disable that access, new privacy toggles give you the ability to turn off camera or microphone access across apps on your phone with a single tap, at any time.

The Pixel 6 and Pixel 6 Pro also include a toggle that lets you remove your device’s ability to connect to less-secure 2G networks. While necessary in certain situations, accessing 2G networks can open up additional attack vectors; this toggle helps users mitigate those risks when 2G connectivity isn’t needed. Built-in security By making all of our products secure by default, Google keeps more people safe online than anyone else in the world. With the Pixel 6 and Pixel 6 Pro, we’re also ratcheting up the dial on default, built-in protections. Our new optical under-display fingerprint sensor ensures that your biometric information is secure and never leaves your device. As part of our ongoing security development lifecycle, Pixel 6 and 6 Pro’s fingerprint unlock has been externally validated by security experts as a strong and secure biometric unlock mechanism meeting the Class 3 strength requirements defined in the Android 12 Compatibility Definition Document (CDD). Phishing continues to be a huge attack vector, affecting everyone across different devices. The Pixel 6 and Pixel 6 Pro introduce new anti-phishing protections. Built-in protections automatically scan for potential threats from phone calls, text messages, emails, and links sent through apps, notifying you if there’s a potential problem. Users are also now better protected against bad apps by enhancements to our on-device detection capabilities within Google Play Protect. Since its launch in 2017, Google Play Protect has provided the ability to detect malicious applications even when the device is offline. The Pixel 6 and Pixel 6 Pro uses new machine learning models that improve the detection of malware in Google Play Protect. The detection runs on your Pixel, and uses a privacy preserving technology called federated analytics to discover commonly-run bad apps. This will help to further protect over 3 billion users by improving Google Play Protect, which already analyzes over 100 billion apps every day to detect threats. Many of Pixel’s privacy-preserving features run inside Private Compute Core, an open source sandbox isolated from the rest of the operating system and apps. Our open source Private Compute Services manages network communication for these features, and uses federated learning, federated analytics, and private information retrieval to improve features while preserving privacy. Some features already running on Private Compute Core include Live Caption, Now Playing, and Smart Reply suggestions. Google Binary Transparency (GBT) is the newest addition to our open and verifiable security infrastructure, providing a new layer of software integrity for your device. Building on the principles pioneered by Certificate Transparency, GBT helps ensure your Pixel is only running verified OS software. It works by using append-only logs to store signed hashes of the system images. The logs are public and can be used to verify that what’s published is the same as what’s on the device – giving users and researchers the ability to independently verify OS integrity for the first time. Beyond the Phone Defense-in-depth isn’t just a matter of hardware and software layers. Security is a rigorous process. Pixel 6 and Pixel 6 Pro benefit from in-depth design and architecture reviews, memory-safe rewrites to security critical code, static analysis, formal verification of source code, fuzzing of critical components, and red-teaming, including with external security labs to pen-test our devices. Pixel is also part of the Android Vulnerability Rewards Program, which paid out $1.75 million last year, creating a valuable feedback loop between us and the security research community and, most importantly, helping us keep our users safe. Capping off this combined hardware and software security system, is the Titan Backup Architecture, which gives your Pixel a secure foot in the cloud. Launched in 2018, the combination of Android’s Backup Service and Google Cloud’s Titan Technology means that backed-up application data can only be decrypted by a randomly generated key that isn't known to anyone besides the client, including Google. This end-to-end service was independently audited by a third party security lab to ensure no one can access a user's backed-up application data without specifically knowing their passcode. To top it all off, this end-to-end security from the hardware across the software to the data center comes with no fewer than 5 years of guaranteed Android security updates on Pixel 6 and Pixel 6 Pro devices from the date they launch in the US. This is an important commitment for the industry, and we hope that other smartphone manufacturers broaden this trend. Together, our secure chipset, software and processes make Pixel 6 and Pixel 6 Pro the most secure Pixel phone yet.

Launching a collaborative minimum security baseline

October 27, 2021

Posted by Royal Hansen, Vice President, Security
Opus and Ponemon Institute studyMinimum Viable Secure Product
How can MVSP help you?

Security teams measuring vendor offerings against a set of minimum security baselines

Internal teams looking to measure your security against minimum requirements
Procurement teams gathering information about vendor servicesLegal teams negotiating contractual controls
Compliance teams documenting processes
community feedbackAcknowledgementsThe work in this post is the result of a collaboration between a large number of security practitioners across the industry including: Marat Vyshegorodtsev, Chris John Riley, Gabor Acs-Kurucz, Sebastian Oglaza, Gen Buckley, and Kevin Clark.

Google Protects Your Accounts – Even When You No Longer Use Them

October 5, 2021

Posted by Sam Heft-Luthy, Product Manager, Privacy & Data Protection Office Colonial PipelineT-Mobile breach Inactive Account ManagerHere’s How it Workssign up

When the account should be considered inactive: You can choose 3, 6, 12 or 18 months of inactivity before Google takes action on your account. Google will notify you a month before the designated time via a message sent to your phone and an email sent to the address you provide.

Who to notify and what to share: You can choose up to 10 people for Google to notify once your Google Account becomes inactive (they won’t be notified during setup). You can also give them access to some of your data. If you choose to share data with your trusted contacts, the email will include a list of the selected data you wanted to share with them, and a link they can follow to download that data. This can include things like photos, contacts, emails, documents and other data that you specifically choose to share with your trusted contact. You can also choose to set up a Gmail AutoReply, with a custom subject and message explaining that you’ve ceased using the account.

If your inactive Google Account should be deleted: After your account becomes inactive, Google can delete all its content or send it to your designated contacts. If you’ve decided to allow someone to download your content, they’ll be able to do so for 3 months before it gets deleted. If you choose to delete your Google Account, this will include your publicly shared data (for example, your YouTube videos, or blogs on Blogger). You can review the data associated with your account on the Google Dashboard. If you use Gmail with your account, you'll no longer be able to access that email once your account becomes inactive. You'll also be unable to reuse that Gmail username.

Privacy Checkuptop five safety tipsSafety Center

Introducing the Secure Open Source Pilot Program

October 1, 2021

Posted by Meder Kydyraliev and Kim Lewandowski, Google Open Source Security Team
Over the past year we have made a number of investments to strengthen the security of critical open source projects, and recently announced our $10 billion commitment to cybersecurity defense including $100 million to support third-party foundations that manage open source security priorities and help fix vulnerabilities.

Today, we are excited to announce our sponsorship for the Secure Open Source (SOS) pilot program run by the Linux Foundation. This program financially rewards developers for enhancing the security of critical open source projects that we all depend on. We are starting with a $1 million investment and plan to expand the scope of the program based on community feedback.

Why SOS?
SOS rewards a very broad range of improvements that proactively harden critical open source projects and supporting infrastructure against application and supply chain attacks. To complement existing programs that reward vulnerability management, SOS’s scope is comparatively wider in the type of work it rewards, in order to support project developers.

What projects are in scope?
Since there is no one definition of what makes an open source project critical, our selection process will be holistic. During submission evaluation we will consider the guidelines established by the National Institute of Standards and Technology’s definition in response to the recent Executive Order on Cybersecurity along with criteria listed below:

The impact of the project:

How many and what types of users will be affected by the security improvements?
Will the improvements have a significant impact on infrastructure and user security?
If the project were compromised, how serious or wide-reaching would the implications be?

The project’s rankings in existing open source criticality research:

Is the project included in the Havard 2 Census Study of most-used packages, or does it have a score of 0.6 or above in the OpenSSF Critically Score project?

What security improvements qualify?
The program is initially focused on rewarding the following work:

Code-Review
Branch-Protection
Pinned-Dependencies
Dependency-Update-Tool
Fuzzing

We'll continue adding to the above list, so check our FAQ for updates. You may also submit improvements not listed above, if you provide justification and evidence to help us understand the complexity and impact of the work.

Only work completed after October 1, 2021 qualifies for SOS rewards.

Upfront funding is available on a limited case by case basis for impactful improvements of moderate to high complexity over a longer time span. Such requests should explain why funding is required upfront and provide a detailed plan of how the improvements will be landed.
How to participate
Review our FAQ and fill out this form to submit your application.

Please include as much data or supporting evidence as possible to help us evaluate the significance of the project and your improvements.

Reward amounts
Reward amounts are determined based on complexity and impact of work:

$10,000 or more for complicated, high-impact and lasting improvements that almost certainly prevent major vulnerabilities in the affected code or supporting infrastructure.
$5,000-$10,000 for moderately complex improvements that offer compelling security benefits.
$1,000-$5,000 for submissions of modest complexity and impact.
$505 for small improvements that nevertheless have merit from a security standpoint.

Looking Ahead
The SOS program is part of a broader effort to address a growing truth: the world relies on open source software, but widespread support and financial contributions are necessary to keep that software safe and secure. This $1 million investment is just the beginning—we envision the SOS pilot program as the starting point for future efforts that will hopefully bring together other large organizations and turn it into a sustainable, long-term initiative under the OpenSSF. We welcome community feedback and interest from others who want to contribute to the SOS program. Together we can pool our support to give back to the open source community that makes the modern internet possible.

Announcing New Patch Reward Program for Tsunami Security Scanner

September 28, 2021

Posted by Guoli Ma, Sebastian Lekies & Claudio Criscione, Google Vulnerability Management Team
publishedTsunami security scannerBug Hunters

Vulnerability detection plugins: In order to expand Tsunami scanner's detection capabilities, we encourage everyone who is interested in making contributions to this project to add new vulnerabilities detection plugins. All plugin contributions will be reviewed by our panel members in Google's Vulnerability Management team and the reward amount will be determined by the severity as well as the time sensitivity of the vulnerability.

Web application fingerprints: Several months ago, we added new web application fingerprinting capabilities to Tsunami that detect popular off-the-shelf web applications. It achieves this goal by matching application fingerprints against a database of known web application fingerprints. More fingerprint data is needed for this approach to support more web applications. You will be rewarded with a flat amount for each application added to the database.

official rules and guidelinestsunami-patch-rewards@google.com

Distroless Builds Are Now SLSA 2

September 22, 2021

Posted by Priya Wadhwa and Appu Goundan, Google Open Source Security Team
signing all distroless images with cosignSLSA 2security framework

SLSA 2 Requirement	Distroless
Source - Version controlled	Source code in Github
Build - Scripted build	Build script exists as a Tekton Pipeline, invoked as a Google Cloud Build step
Build - Build service	All steps run on Kubernetes with Tekton
Provenance - Available	Provenance is available in the rekor transparency log as an in-toto attestation
Provenance - Authenticated	Provenance is signed with the distroless GCP KMS key
Provenance - Service generated	Provenance is generated by Tekton Chains from a Tekton TaskRun

Achieving SLSA 2 required some changes to the distroless build pipeline: we set up Tekton Pipelines and Tekton Chains in a GKE cluster to automate building images and generating provenance. Every time a pull request is merged to the distroless Github repo, a Tekton Pipeline is triggered. This Pipeline builds the distroless images, and Tekton Chains is responsible for generating signed provenance for each image. Tekton Chains stores the signed provenance alongside the image in an OCI registry and also stores a record of the provenance in the rekor transparency log.

Don't trust us?

You can try the build yourself. Because distroless builds are reproducible, all the information to replicate the build is in the provenance, and you or a trusted third party can build the image yourselves and verify the build is correct by matching image digests.

You can verify an attestation for a distroless image with cosign and the distroless public key:

$ cosign verify-attestation -key cosign.pub gcr.io/distroless/base@sha256:4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91

Verification for gcr.io/distroless/base@sha256:4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91 --

The following checks were performed on each of these signatures:

- The cosign claims were validated

- The signatures were verified against the specified public key

- Any certificates were verified against the Fulcio roots.

...

And you can find the provenance for the image in the rekor transparency log with the rekor-cli tool. For example, you could find the provenance for the above image by using the image’s digest and running:

$ rekor-cli search --sha sha256:4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91

af7a9687d263504ccdb2759169c9903d8760775045c6e7554e365ec2bf29f6f8

$ rekor-cli get --uuid af7a9687d263504ccdb2759169c9903d8760775045c6e7554e365ec2bf29f6f8 --format json | jq -r .Attestation | base64 --decode | jq

{

"_type": "distroless-provenance",

"predicateType": "https://tekton.dev/chains/provenance",

"subject": [

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "703a4726aedc9ec7a7e32251087565246db117bb9a141a7993d1c4bb4036660d"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "d322ed16d530596c37eee3eb57a039677502aa71f0e4739b0272b1ebd8be9bce"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "2dfdd5bf591d0da3f67a25f3fc96d929b256d5be3e0af084db10952e5da2c661"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "4f8aa0aba190e375a5a53bb71a303c89d9734c817714aeaca9bb23b82135ed91"

}

{

"name": "gcr.io/distroless/base",

"digest": {

"sha256": "dc0a793d83196a239abf3ba035b3d1a0c7a24184856c2649666e84bc82fc5980"

}

{