'They can actually change their code to force your browser to send them your Mega encryption keys, or change the code to disable crypto from the get-go,' says Kobeissi, who ran his own Cryptocat encrypted chat site with the same no-download model in 2011, but switched to a more secure browser plug-in after widespread criticism. law enforcement could even force administrators to hijack the servers' encryption commands. Kobeissi says he's traced several of Mega's servers to the United States, which would mean U.S. So Mega, or anyone else who gains control of the Mega server sending the crypto algorithms, can turn off that encryption or steal the user's private key, which would allow decryption of all past and future uploads. When a website loads all the encryption code in a user's browser from a remote server, it can change that code without the user's knowledge.

That's a tempting convenience for users, but it's also a setup that has been widely debunked as insecure. 'Unlike the industry norm where the cloud storage provider holds the decryption key, with MEGA, you control the encryption, you hold the keys, and you decide who you grant or deny access to your files, without requiring any risky software installs,' reads the company's website. Mega describes that system as 'User-Controlled Encryption.' All of the encryption takes place in the user's browser automatically when he or she visits the site.

The most glaring issue for Kobeissi is that Mega claims to offer end-to-end encryption of users' files without requiring them to download any software.

Mega decrypting forever