Deadrop is a secure way to upload a file (25M or smaller) and later retreive it via a link and a password/passphrase. It is similar to tools like Dropbox but with less features and a focus on security. All files are stored in an encrypted format using your password as the key with a unique IV per file, passwords are stored in a hashed format using bcrypt, and when files are removed they are securely deleted. An in depth overview of the security features can be found here.