hasdicepass

Diceware passphrases are a approach to create a complex password that is hard to guess but easy to remember. It is actually not recommended to use a computer to generate those passphrases, but "what I cannot create I cannot understand" (Feynman). If you actually want to use a computer for random selection of words from a list, there are much simpler algorithms for much more generic list than diceword lists.

Diceword lists, for example, are size restricted. The number of words must match a power of six.

Usage

You'll have to download a diceword list from the above webpage or create your own. And then provide the name and a number after the -n parameter to hasdicepass.

A diceword list is a line-oriented file. Each line starts with a sequence of numbers in the range [1,6] and a word (letters and numbers without spaces). For this current version you'll have to ensure that all lines consist the same number of digits and that every combination of digits is included. Strange errors might occur otherwise.

Implementation

There are three parts that could be used for computer programming lessons. I invite you to get your own version build. I would be interested in improvements or different solutions.

• Parsing of diceword lists
• Generating a diceword tree
• Locating a word given a sequence of random numbers (of the correct length)

After parsing the diceword list the program compiles the list into a tree, ordered by numbers. This is, for the practical problem at hand, definitely overengineered and probably increases the runtime for most practical number of output words. But if you happen to require a million words, it probably runs a little faster. More important, it is a more beautiful way to store the decision tree that essentially is the thing a diceword list resembles.

I chose an implementation that is at all points oblivious to the number of dices thrown (the length of the diceword list, i.e. the number of digits in each line in the diceword file). Thus, in theory you could use it with unbalanced diceword trees, but this would obviously reduce the randomness of results.

Word location (implemented in the diceword function) turned out to be rather complex due to error handling. If a word is not found the error will provide you with the exact location where your list is lacking a word.

Wordlist Parsing

If you take a closer look at the Wordlist parser, you'll find that there are two versions. After fiddling with generating generic parser DSL and some (yet unknown) problem with the parsing of sequences, I went for a very simplistic parser.