Google Adds Support for DNS-over-HTTP/3 in Android to Keep DNS Queries Private

Google on Tuesday officially announced support for
DNS-over-HTTP/3 (DoH3) for Android devices as part of a Google Play
system update designed to keep DNS queries private.

To that end, Android smartphones running Android 11 and higher
are expected to use DoH3 instead of DNS-over-TLS (DoT), which was
incorporated into the mobile operating system with Android 9.0.

DoH3 is also an alternative to DNS-over-HTTPS (DoH^[1]), a mechanism for
carrying out remote Domain Name System (DNS) resolution through an
encrypted connection, effectively preventing third parties from
snooping on users’ browsing activities.

HTTP/3^[2], the first major upgrade
to the hypertext transfer protocol since HTTP/2 was introduced in
May 2015, is designed to use a new transport layer protocol called
QUIC^[3]
that’s already supported by major browsers such as Google Chrome,
Microsoft Edge, Mozilla Firefox, and Apple Safari.

The low-latency protocol, developed by Google in 2012, relies on
the User Datagram Protocol (UDP) rather than the Transmission
Control Protocol (TCP) to make HTTP traffic more secure and efficient^[4], not to mention reduce
the time it takes to establish connections between two
endpoints.

“While using HTTPS alone will not reduce the overhead
significantly, HTTP/3 uses QUIC, a transport that efficiently
multiplexes multiple streams over UDP using a single TLS session
with session resumption,” Matthew Maurer and Mike Yu from the
Android team said^[5]
in a post.

DoH3 further has the advantage of maintaining stable connections
even when mobile devices frequently change networks (e.g., from
Wi-Fi to LTE). “With DoT, these events require a full renegotiation
of the connection. By contrast, the QUIC transport HTTP/3 is based
on can resume a suspended connection in a single RTT,” Google
noted.

What’s more, to improve the security of the DNS resolver, the
component has been implemented in Rust, enabling memory safe
guarantees. It’s worth pointing out that Google added Rust support^[6] to Android in April
2021.

“With the introduction of Rust, we are able to improve both
security and the performance at the same time,” Maurer and Yu said.
“Likewise, QUIC allows us to improve network performance and
privacy simultaneously.”