- ExpressVPN is developing a CSAM blocking tool in collaboration with the IWF
- OpenBoundary blocks known CSAM domains at the DNS level
- The tool is open source so other services can integrate it
As regulators around the world scramble for solutions to increase online children’s safety, VPN services are often targeted for their alleged role in facilitating anonymous access to illegal content.
ExpressVPN is now taking a proactive stance against one of the internet’s most heinous crimes by building a dedicated tool that stops access to child sexual abuse material (CSAM).
The provider partnered with the Internet Watch Foundation (IWF) to develop Open bordera server-level toolset designed to help network operators securely and transparently restrict access to verified CSAM domains.
ExpressVPN maintains that OpenBoundary is built on a privacy-first infrastructure that introduces network-wide security measures without changing or violating its strict no-logs policy.
Dr. Peter Membrey, chief research officer at ExpressVPN, told TechRadar that the move is a “definite first step in opening up the conversation” between technologists, child safety groups and regulators.
He added: “We believe there is no good reason for this material to exist or cross our network – but it doesn’t have to be all or nothing.” He believes OpenBoundary gives regulators “sharper tools” that don’t weaken encryption or user privacy in the name of security.
As part of the “Not on My Network” initiative, ExpressVPN is opening the code to OpenBoundary. The goal is for other VPN services, Internet Service Providers (ISPs) and cloud platforms to adopt the framework.
Fellow Kape Technologies brands CyberGhost and Private Internet Access (PIA) are the first to join the mission. Kerry Smith, executive director at the IWF, welcomed the innovative approach, saying the move “balances its commitment to online child safety and online privacy.”
This is how OpenBoundary works
The technical implementation of OpenBoundary is straightforward. The tool works at the DNS level and blocks domains that appear on the human-verified IWF list.
This happens automatically when a user connects to the VPN app, preventing known CSAM domains from loading. Membrey explains that if a user tries to visit a flagged site, the system simply returns an error stating that the site does not exist.
Crucially, this process does not involve traffic inspection, monitoring or breaking encryption. Instead, it is a straightforward domain block.
While some advocates argue that any content filtering goes against the “neutral” nature of a VPN, Membrey says he’s “comfortable with blocking” sites that exclusively host CSAM material.
“We don’t want this stuff going through our network. We don’t want to be part of this,” he told Techradar.
Bridging the gap between security and privacy
Until now, the fight against CSAM content has largely focused on exposing illegal material.
In the EU, the proposed law, nicknamed Chat Control, which is now in its final legislative step, has attracted strong opposition from politicians, scientists and technologists alike. Now the UK is also tracking CSAM scanning obligations under the Online Safety Act.
In both cases, critics have pointed out how today’s detection technologies—whether client-side scanning or hash-matching—are technically ineffective while inevitably harming the privacy and security of all online services that are supposed to implement these controls.
ExpressVPN’s new tool certainly doesn’t come as a technical solution to CSAM scanning and detection, but rather it’s a way to recalibrate the discussion towards what we can do now. A first step to mitigate the problem and bridge the gap between privacy, security and children’s safety on the Internet.
Commenting on this point, Membrey told TechRadar: “Our pitch is simple: ‘Not on my network.’ We encourage lawmakers to collaborate and innovate before they legislate and regulate. It’s much easier to undo a failed technology solution than to undo a blanket law passed by a parliament or congress.”
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