Ruthenium is a custom build of Chromium for Android that adds support for the Russian Trusted Root CA certificate from the Ministry of Digital Development without modifying the system certificate store.
Many Russian banks and government services use TLS chains ending at this root. Standard Google Chrome on Android rejects these chains with NET::ERR_CERT_AUTHORITY_INVALID because the root is absent from Chromium’s built-in store. The author wanted to keep using Chrome’s interface and therefore created a separate APK that includes the root with strict DNS constraints limited to .ru and .рф zones.
Why Chrome rejects the chain
The browser receives the site certificate and intermediates, validates names, validity periods and signatures, then attempts to build a path to a trusted root. Because Russian Trusted Root CA is not present in Chromium, verification fails. Existing solutions either require switching to another browser or installing the root into Android’s system store, which affects all applications.
Technical implementation of the patch
The certificate is converted from PEM to DER and embedded as a byte array in chrome/browser/net/profile_network_context_service.cc. The patch creates a CertWithConstraints object that adds the root with permitted_dns_names set to {“.ru”, “.xn--p1ai”}. This constraint applies to all DNS names listed in the certificate’s Subject Alternative Name, preventing misuse outside the allowed TLDs. The build scripts verify the DER SHA-256 against a lock file before compilation.
Four C++ files are modified in total: the network context service for the constrained root, primary_account_manager.cc to disable browser-level sign-in by default, and two omnibox/searchbox files to replace unavailable XR icon methods on Android builds without VR support.
Build configuration and distribution
The release uses is_official_build=true with ThinLTO enabled but external PGO profiles disabled. VR and AR features are turned off via GN flags. Each APK is published with a release tag that incorporates the Chromium revision, certificate digest, and build arguments, enabling traceability. Checksums, ABI information, and apksigner verification results accompany every binary.
Ruthenium installs under the package name app.ruthenium.browser and keeps its data separate from Chrome. No auto-update mechanism is provided; users must install new versions manually. The browser behaves identically to upstream Chromium on non-Russian domains.
