It looks like they know what they're doing. I was especially curious about deduplication. The way they do it sounds perfectly reasonable:
> MEGA indeed uses deduplication, but it does so based on the entire file post-encryption rather than on blocks pre-encryption. If the same file is uploaded twice, encrypted with the same random 128-bit key, only one copy is stored on the server. Or, if (and this is much more likely!) a file is copied between folders or user accounts through the file manager or the API, all copies point to the same physical file.
> MEGA indeed uses deduplication, but it does so based on the entire file post-encryption rather than on blocks pre-encryption. If the same file is uploaded twice, encrypted with the same random 128-bit key, only one copy is stored on the server. Or, if (and this is much more likely!) a file is copied between folders or user accounts through the file manager or the API, all copies point to the same physical file.