Send MobileCoin Globally: Encrypted Messaging App Introduces Beta Payments Feature

In the spring of 2021, Signal announced that it would be rolling out a payments feature integrating the privacy-focused cryptocurrency, MobileCoin, in beta for its UK users. However, the feature has been available to all Signal users globally since mid-November of 2020, without any fanfare. The payments feature allows for digital payments that are much more private than credit card transactions or Bitcoin transfers.

The founder of MobileCoin, Josh Goldbard, confirmed that the rollout spurred massive adoption of the cryptocurrency, with thousands of daily transactions compared to just dozens before the global beta release. Goldbard suggests that over a hundred million devices on the planet have the ability to turn on MobileCoin and send an end-to-end encrypted payment in five seconds or less.

Though the payments feature is accessible to all Signal users, getting started with MobileCoin may be a challenge for some. While anyone outside of sanctioned countries like North Korea and Syria can access their MobileCoin wallet within a message by tapping the “+” icon and then “payment,” the main challenge is loading the wallet in the first place. Currently, the cryptocurrency is listed for sale on only a few smaller cryptocurrency exchanges such as BitFinex and FTX, and none of them yet offer it to US consumers.

Signal itself didn’t respond to WIRED’s requests for comment on the global rollout of the payments feature. But last April, Signal creator Moxie Marlinspike explained to WIRED that he wanted to add payments to the encrypted video-calling and texting app to match features from rivals like WhatsApp and Facebook Messenger—while also bringing Signal’s lauded privacy protections to monetary transactions. “I would like to get to a world where not only can you feel [a sense of privacy] when you talk to your therapist over Signal, but also when you pay your therapist for the session over Signal,” Marlinspike said at the time.

Marlinspike has argued that sort of monetary privacy requires integration with a cryptocurrency rather than traditional, surveillance-friendly banking and credit card systems. In 2017, Marlinspike helped launch MobileCoin with that potential integration in mind, serving as a paid technical advisor for the cryptocurrency. He and Goldbard say they designed MobileCoin to be both easier to use for small purchases on a mobile device, with fast transaction confirmations, and also far more private than Bitcoin, whose public blockchain can allow powerful forms of tracking.

To avoid that blockchain-based tracing of user finances, MobileCoin deploys techniques that have been pioneered in older “privacy coins” such as Monero and Zcash. Those include a protocol called CryptoNote and a feature called Ring Confidential Transactions, which hides the amount of payments and makes them hard to trace by mixing them up. MobileCoin also uses a form of mathematical proof known as Bulletproofs that can guarantee a transaction has occurred without revealing its value. “I don’t think it’s reasonable to send transactions over a ledger where all actions can be linked,” Goldbard says of Bitcoin’s less-private blockchain. “There are so many different ways that this has problems. If I pay my bills, my barista now knows that I just paid my therapist or I went to the doctor. Every transaction that I make with that wallet is now visible to my barista, forever.”

Goldbard has announced that individuals in the United States will soon be able to buy and sell MobileCoin with greater ease. As part of this effort, MobileCoin has entered into agreements with cryptocurrency payment processor Zero Hash and cryptocurrency trading platform SFOX. These deals are set to take effect within the first three months of 2022. Americans will be able to purchase MobileCoin through payment processors using the Zero Hash deal, which is seen as a major breakthrough. With these agreements in place, MobileCoin is poised to expand its reach and gain a greater foothold in the US crypto market.

The same regulatory restrictions on cryptocurrency that make it hard to buy and sell MobileCoin in the US, though, also worry some privacy advocates. They fear that integrating a privacy coin into Signal could create new legal headaches for a communications tool that millions of people rely on. “Signal is super important,” says Matt Green, a cryptographer at Johns Hopkins University. “I’m very nervous they’re going to get themselves into a problematic situation by flirting with this kind of payment infrastructure when there’s so much legislation and regulation around it.” (Green notes that he’s also a creator of the privacy coin Zcash, which might be seen as a MobileCoin competitor, but he says he would have the same concerns if Signal were to integrate Zcash instead of MobileCoin.)

The US federal government has, after all, threatened a hardline approach to cryptocurrencies, particularly those that allow any sort of anonymous transactions. A new “enforcement framework” the Justice Department published in the fall of 2020 and new rules from the US Treasury Department’s FinCEN group may compel more companies in the cryptocurrency industry to collect identifying information on users. And two provisions in the infrastructure funding bill that Congress passed last year seem to require cryptocurrency businesses and users to report to the IRS the social security number of the sender or recipient of certain payments.

Civil liberties attorney Marta Belcher, who advises the Electronic Frontier Foundation on cryptocurrency issues, believes that Signal’s integration of MobileCoin is a welcome development. She sees it as a way of bringing the anonymity and privacy benefits of cash into the digital realm. However, she also points out the challenges facing any company that enters the cryptocurrency space. Belcher warns that companies concerned about civil liberties should be aware of the current regulatory landscape in the US, which is emphasizing expanded surveillance of traditional banking systems for greater transparency in cryptocurrency. Although it is unclear whether Signal will be affected by the regulations, the integration of MobileCoin can potentially expose it to scrutiny. With millions of users soon able to transact in a relatively anonymous cryptocurrency, Signal’s regulatory compliance may be a pressing issue.