Andy Greenberg writes: “MiniLock can be used to encrypt anything from video email attachments to photos stored on a USB drive, or to encrypt files for secure storage on Dropbox or Google Drive. … miniLock offers so-called “public key” encryption. In public key encryption systems, users have two cryptographic keys, a public key and a private one. They share the public key with anyone who wants to securely send them files; anything encrypted with that public key can only be decrypted with their private key, which the user guards closely. [miniLock creator Nadim] Kobeissi’s version of public key encryption hides nearly all of that complexity. There’s no need to even register or log in—every time miniLock launches, the user enters only a passphrase, though miniLock requires a strong one with as many as 30 characters or a lot of symbols and numbers. From that passphrase, the program derives a public key, which it calls a miniLock ID, and a private key, which the user never sees and is erased when the program closes. Both are the same every time the user enters the passphrase. That trick of generating the same keys again in every session means anyone can use the program on any computer without worrying about safely storing or moving a sensitive private key.”