Mega, the New Zealand-based file-sharing biz co-founded a decade ago by Kim Dotcom, promotes its "privacy by design" and user-controlled encryption keys to claim that data stored on Mega's servers can only be accessed by customers, even if its main system is taken over by law enforcement or others.
The design of the service, however, falls short of that promise thanks to poorly implemented encryption. Cryptography experts at ETH Zurich in Switzerland on Tuesday published a paper describing five possible attacks that can compromise the confidentiality of users' files.
The paper [PDF], titled "Mega: Malleable Encryption Goes Awry," by ETH cryptography researchers Matilda Backendal and Miro Haller, and computer science professor Kenneth Paterson, identifies "significant shortcomings in Mega’s cryptographic architecture" that allow Mega, or those able to mount a TLS MITM attack on Mega's client software, to access user files.