Encrypted messaging app Signal is testing a new feature that’ll let you privately send money to your friends—without going through major financial networks.

To pull this off, the app is adding the ability to pay in a cryptocurrency known as MobileCoin. It will launch first for users in the UK who are using the beta version of the mobile app. 

Signal’s claim to fame is the messaging app’s end-to-end encryption. This means not even the provider can read the content of your messages—only you and the recipient of the messages. Adding a payment system would certainly help improve Signal’s functionality. But it could also upend the app’s privacy since users would be paying each other with money from their bank accounts or credit cards, leaving an easily traceable financial trail. 

To maintain privacy, Signal developers decided to use the financial network run by MobileCoin(Opens in a new window), which is designed to encrypt all transactions made with the cryptocurrency. As a result, only the sender and recipient of payment should be able to track the transaction. (In contrast, Bitcoin transactions are recorded on the blockchain, which acts as a public ledger.)

“As always, our goal is to keep your data in your hands rather than ours,” Jun Harada, Signal’s head of growth in communication, wrote in an announcement(Opens in a new window). “MobileCoin’s design(Opens in a new window) means Signal does not have access to your balance, full transaction history, or funds.”

Tweet(Opens in a new window)

In an interview(Opens in a new window) with Wired, Signal’s creator Moxie Marlinspike added: “There’s a palpable difference in the feeling of what it’s like to communicate over Signal, knowing you’re not being watched or listened to, versus other communication platforms. I would like to get to a world where not only can you feel that when you talk to your therapist over Signal, but also when you pay your therapist for the session over Signal.”

Activating the payment feature will create a MobileCoin wallet with your Signal account. The cryptocurrency can then be sent and received to and from your friends in less than 10 seconds. 

However, the big obstacle facing the feature is MobileCoin’s lack of adoption. The cryptocurrency is currently only available on the UK’s FTX(Opens in a new window) exchange platform, where it’s going for $65 a coin. Cryptocurrencies also tend to wildly swing in price, so any money sent using MobileCoin could explode in worth or plummet in value.  

At the same time, not everyone is happy with Signal’s decision to add cryptocurrency payments. “I think this is an incredibly bad idea,” wrote(Opens in a new window) Bruce Schneier, a noted computer security expert.

“It’s not just the bloating of what was a clean secure communications app. It’s not just that blockchain is just plain stupid(Opens in a new window). It’s not even that Signal is choosing to tie itself to a specific blockchain currency. It’s that adding a cryptocurrency to an end-to-end encrypted app muddies the morality of the product, and invites all sorts of government investigative and regulatory meddling: by the IRS, the SEC, FinCEN, and probably the FBI,” he explained.

Despite some public backlash, Signal is hoping users in the UK will help out in testing the payment feature. It then plans on expanding the beta in the future.

Editor’s note: This story has been updated to note the backlash against the payment feature.