Android 17 Rolls Out ECH: Browser Domains Hidden From Your ISP

Google is preparing a set of networking changes for Android 17 aimed at connection privacy, the fight against cellular vulnerabilities, and protecting users' home networks.

Encrypting the Site Name

The headline feature is support for the Encrypted Client Hello (ECH) standard, which works in tandem with private DNS and hides metadata, including the names of the domains you visit. ECH acts as a privacy extension for TLS — the protocol behind HTTPS. It encrypts the opening part of the TLS handshake, where the host name is transmitted in the clear through the Server Name Indication (SNI) field. Even over a secure connection, internet providers and Wi-Fi operators can see which resource you're reaching out to, and can collect that data for commercial profiling.

Previously, Android users only got ECH when using Chrome 117+ or Firefox 119+; now the protection is built in at the system level. For apps targeting Android 17, ECH will be enabled by default — provided a compatible networking library is in use, such as recent versions of OkHttp, WebView, or HttpEngine.

If the server supports ECH, Android encrypts the host name. If it doesn't, the system still sends a dummy field that looks like ECH (so-called ECH GREASE), so that genuine ECH connections don't stand out from the crowd; in this case, though, the host name remains visible. Jigsaw, Google's unit focused on privacy and censorship circumvention, tested ECH GREASE against ten thousand popular domains and across 740 provider networks in 202 countries — and found no problems loading sites and no unexpected blocking.

Local Network, Certificates, and Dropping 2G

Beyond ECH, Google introduced several more network protection measures. Local Network Protection now requires apps to request permission before scanning for or connecting to devices on the user's local network.

Certificate Transparency is enabled by default in Android 17: site certificates must appear in public logs, which makes the use of forged certificates more noticeable.

Finally, participating mobile carriers will be able to automatically disable 2G for subscribers. This reduces the risk from so-called SMS blasters and rogue base stations, which can send out malicious messages or intercept sensitive traffic from nearby devices.

Source: Bleeping Computer