Your MiniBluebox document will be encrypted with Skein cryptographic hash functions, using a 512-bit hash value generated from your Master Key. Even if you loose your document or strangers get hold of it, no one will be able to unlock it, with or without using MiniBluebox, unless they know your Master Key or unless your Master Key is too weak.
Hackers most often use a dictionary attack. A dictionary attack is carried out with an automated program that will enter thousands of words sequentially read from a dictionary, until one of them unlocks your document or until all words in the dictionary are consumed. Your Master Key should not be in that list.
It is important to construct your Master Key carefully. It should be be at least 12 characters long, mixed with numbers, letters and other characters. You can also use characters in locales other than English.
A simple and a very effective method to maximise the strength of your Master Key is to use many words separated by space characters. Example: "between words".
You can make the Master Key stronger by setting characters at particular positions as CAPITAL. Example: "beTween woRds".
Even a stronger Master Key can be specified by setting certain characters with a decimal digit resembling that character. Example: "b3Tw33n w0Rd5".
Or make your Master Key longer. Example: "Between words and worlds"
Ensure to focus and set time to memorise your Master Key. Don't rush.
Don't write your Master Key anywhere.
If you forget your Master Key you cannot unlock and open your document.
This is called zero tolerance security policy.