Note: the tables below are part of the DiceTables PDF document, which is included with the DiceWords package that is installed in Centrych. The document was generated from a LibreOffice spreadsheet, which is included in the same directory.
While Diceware (tm) is mostly known for using dice to generate passphrases, the Diceware FAQ includes an entry on using dice to generate random character strings and three others for generating case-insensitive alphanumeric, decimal and hexadecimal strings. While those six tables worked for us for quite a while, there was always a feeling that they could be improved.
The areas that we felt in need of improvement were:
In the end, we were quite successful. With just 8 different tables we were able to represent the following 14 character sets:
We were also able to make re-rolls easier to identify by grouping the unused spaces to the lower right of each table, except for the hexadecimal table, which mapped to a much better re-roll identification pattern.
Printable ASCII (95 characters)
For this purpose of this document we've included just the three tables that are needed for generating random character strings that can contain any of the 95 possible characters on a standard US keyboard with 3 dice.
While any 3 dice can be used, we will refer to them here as yellow, green and red since their function maps directly to the same-colored indexes in each of the tables.
The yellow die selects the table. A roll of a yellow 1 or 2 would select the left table, a 3 or 4 would mean the middle table, while a 5 or 6 would indicate the right table.
From there it's a simple matter of looking up what character was selected by finding the location indicated by the red and green dice.
For example, a y3r2g5 (yellow 3, red 2, green 5) would select the ')' symbol from the center table.
The lightly shaded, blank areas in the lower right of each table indicate a re-roll. For every table, regardless of which die it may be, a roll of 6,5 or 6,6 requires a re-roll. For the left and right tables there's an additional re-roll requirement for a 6,4 roll, again, regardless of die color.
The middle table shows an additional re-roll rule which is only used when the space character, indicated by sp in the table, is not used. In that case, it's treated as a blank and a roll of 5,5 would then require a re-roll.
As mentioned previously, except for the hexadecimal table, the other seven have been designed so that the re-rolls are not sensitive to die color. Rolling a 6,6 or a 6,5, and often a 6,4, will require a re-roll. This may sound confusing at first, but a few rolls of the dice while referring to the tables in the document will make them second-nature to you in relatively short order.