The EU could force WhatsApp, Signal, iMessage and other messaging services to work together. It sounds like a dream, but it could turn into a nightmare.

A new EU law, the Digital Markets Act (DMA), is designed to allow smaller players to compete with the tech industry’s established giants. Part of the law states that users should be able to message each other, regardless of which messaging app they’re using. But this could have some pretty serious implications for security and privacy, which is — ironically — another focus of the DMA.

"The biggest challenge with interoperability is agreeing on a common protocol, common code, and means to integrate the different technologies or build a new technology," global cybersecurity assessor Andy Rogers told Lifewire via email. "We need to standardize the technology so that everyone is working from the same sheet of music. When you decide to integrate a technology that is standardized with your own technology, like iMessage did with SMS, you can sometimes end up with a bit of a kludge because you're integrating two technologies that weren't meant to work together."

Messaging platforms are valuable because they have a lot of lock-in. For example, if you, your friends, and your work contacts all use WhatsApp, there’s no way you’re going to switch to Signal. We get around this now by having all the messaging apps on our devices and using what we need depending on who we’re talking to. The DMA would force platform providers like Apple and Facebook to make their services work with each other.