Elon Musk spent his Friday reposting criticism of competitors after the launch of the XChat app, a standalone messaging option for X users. “Signal, WhatsApp, Telegram, and iMessage all have serious security problems,” read a message Musk reposted, in part. “XChat is the only secure, encrypted messaging app.” Encryption experts I spoke with in the lead-up to this launch expressed cautious skepticism about XChat’s execution and defended other communication platforms, like Signal, as solid choices. One of XChat’s red flags is that users must connect an existing X account to log in and start messaging. “I’m a little suspicious of that, because the more data points you connect together about a person, the more you can track what they’re doing,” says Maria Villegas Bravo, counsel at the Electronic Privacy Information Center. Bravo considers Musk’s past attacks on other apps to be worrisome and self-serving. Last year, when Musk unveiled XChat as a revamped, encrypted version of direct messages on X, security experts questioned the effectiveness of storing users’ cryptographic keys on X’s servers rather than …