Posted by Yang Lu, Software Engineer, Angana Ghosh, Group Product Manager, and Xu Liu, Director of Engineering, Gboard team

Google Keyboard (a.k.a Gboard) has a critical mission to provide frictionless input on Android to empower users to communicate accurately and express themselves effortlessly. In order to accomplish this mission, Gboard must also protect users’ private and sensitive data. Nothing users type is sent to Google servers. We recently launched privacy-preserving input by further advancing the latest federated technologies. In Android 11, Gboard also launched the contextual input suggestion experience by integrating on-device smarts into the user’s daily communication in a privacy-preserving way.

Before Android 11, input suggestions were surfaced to users in several different places. In Android 11, Gboard launched a consistent and coordinated approach to access contextual input suggestions. For the first time, we’ve brought Smart Replies to the keyboard suggestions – powered by system intelligence running entirely on device. The smart input suggestions are rendered with a transparent layer on top of Gboard’s suggestion strip. This structure maintains the trust boundaries between the Android platform and Gboard, meaning sensitive personal content cannot be not accessed by Gboard. The suggestions are only sent to the app after the user taps to accept them.

For instance, when a user receives the message “Have a virtual coffee at 5pm?” in Whatsapp, on-device system intelligence predicts smart text and emoji replies “Sounds great!” and “👍”. Android system intelligence can see the incoming message but Gboard cannot. In Android 11, these Smart Replies are rendered by the Android platform on Gboard’s suggestion strip as a transparent layer. The suggested reply is generated by the system intelligence. When the user taps the suggestion, Android platform sends it to the input field directly. If the user doesn’t tap the suggestion, gBoard and the app cannot see it. In this way, Android and Gboard surface the best of Google smarts whilst keeping users’ data private: none of their data goes to any app, including the keyboard, unless they’ve tapped a suggestion.

Additionally, federated learning has enabled Gboard to train intelligent input models across many devices while keeping everything individual users type on their device. Today, the emoji is as common as punctuation – and have become the way for our users to express themselves in messaging. Our users want a way to have fresh and diversified emojis to better express their thoughts in messaging apps. Recently, we launched new on-device transformer models that are fine-tuned with federated learning in Gboard, to produce more contextual emoji predictions for English, Spanish and Portuguese.

Furthermore, following the success of privacy-preserving machine learning techniques, Gboard continues to leverage federated analytics to understand how Gboard is used from decentralized data. What we’ve learned from privacy-preserving analysis has let us make better decisions in our product.

When a user shares an emoji in a conversation, their phone keeps an ongoing count of which emojis are used. Later, when the phone is idle, plugged in, and connected to WiFi, Google’s federated analytics server invites the device to join a “round” of federated analytics data computation with hundreds of other participating phones. Every device involved in one round will compute the emoji share frequency, encrypt the result and send it a federated analytics server. Although the server can’t decrypt the data individually, the final tally of total emoji counts can be decrypted when combining encrypted data across devices. The aggregated data shows that the most popular emoji is 😂 in Whatsapp, 😭 in Roblox(gaming), and ✔ in Google Docs. Emoji 😷 moved up from 119th to 42nd in terms of frequency during COVID-19.

Gboard always has a strong commitment to Google’s Privacy Principles. Gboard strives to build privacy-preserving effortless input products for users to freely express their thoughts in 900+ languages while safeguarding user data. We will keep pushing the state of the art in smart input technologies on Android while safeguarding user data. Stay tuned!

Posted by Kylie McRoberts, Program Manager and Alec Guertin, Security Engineer

Google’s Android Security & Privacy team has launched the Android Partner Vulnerability Initiative (APVI) to manage security issues specific to Android OEMs. The APVI is designed to drive remediation and provide transparency to users about issues we have discovered at Google that affect device models shipped by Android partners.

Another layer of security

Android incorporates industry-leading security features and every day we work with developers and device implementers to keep the Android platform and ecosystem safe. As part of that effort, we have a range of existing programs to enable security researchers to report security issues they have found. For example, you can report vulnerabilities in Android code via the Android Security Rewards Program (ASR), and vulnerabilities in popular third-party Android apps through the Google Play Security Rewards Program. Google releases ASR reports in Android Open Source Project (AOSP) based code through the Android Security Bulletins (ASB). These reports are issues that could impact all Android based devices. All Android partners must adopt ASB changes in order to declare the current month’s Android security patch level (SPL). But until recently, we didn’t have a clear way to process Google-discovered security issues outside of AOSP code that are unique to a much smaller set of specific Android OEMs. The APVI aims to close this gap, adding another layer of security for this targeted set of Android OEMs.

Improving Android OEM device security

The APVI covers Google-discovered issues that could potentially affect the security posture of an Android device or its user and is aligned to ISO/IEC 29147:2018 Information technology — Security techniques — Vulnerability disclosure recommendations. The initiative covers a wide range of issues impacting device code that is not serviced or maintained by Google (these are handled by the Android Security Bulletins).

Protecting Android users

The APVI has already processed a number of security issues, improving user protection against permissions bypasses, execution of code in the kernel, credential leaks and generation of unencrypted backups. Below are a few examples of what we’ve found, the impact and OEM remediation efforts.

Permission Bypass

In some versions of a third-party pre-installed over-the-air (OTA) update solution, a custom system service in the Android framework exposed privileged APIs directly to the OTA app. The service ran as the system user and did not require any permissions to access, instead checking for knowledge of a hardcoded password. The operations available varied across versions, but always allowed access to sensitive APIs, such as silently installing/uninstalling APKs, enabling/disabling apps and granting app permissions. This service appeared in the code base for many device builds across many OEMs, however it wasn’t always registered or exposed to apps. We’ve worked with impacted OEMs to make them aware of this security issue and provided guidance on how to remove or disable the affected code.

Credential Leak

A popular web browser pre-installed on many devices included a built-in password manager for sites visited by the user. The interface for this feature was exposed to WebView through JavaScript loaded in the context of each web page. A malicious site could have accessed the full contents of the user’s credential store. The credentials are encrypted at rest, but used a weak algorithm (DES) and a known, hardcoded key. This issue was reported to the developer and updates for the app were issued to users.

Overly-Privileged Apps

The checkUidPermission method in the PackageManagerService class was modified in the framework code for some devices to allow special permissions access to some apps. In one version, the method granted apps with the shared user ID com.google.uid.shared any permission they requested and apps signed with the same key as the com.google.android.gsf package any permission in their manifest. Another version of the modification allowed apps matching a list of package names and signatures to pass runtime permission checks even if the permission was not in their manifest. These issues have been fixed by the OEMs.

More information

Keep an eye out at https://bugs.chromium.org/p/apvi/ for future disclosures of Google-discovered security issues under this program, or find more information there on issues that have already been disclosed.

Acknowledgements: Scott Roberts, Shailesh Saini and Łukasz Siewierski, Android Security and Privacy Team