The Password Grid - A Password Strategy

First published on February 18, 2000

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This is a strategy for protecting your encrypted data such that you will always have the option of easily and quickly destroying the data forever in the event your system is compromised, stolen, or confiscated. Nobody, not even you, will have the ability to recover it, so long as the encryption software you are using is secure.

http://arstechnica.com/tech-policy/news/2009/03/court-self-incrimination-privilege-stops-with-passwords.ars

Court: self-incrimination privilege won't protect password

The privilege against self-incrimination, a federal court has ruled, does not bar prosecutors from forcing a defendant to decrypt his laptop hard drive...

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You can neutralize the dreaded "$5 wrench" encryption hack (also known as "rubber hose cryptanalysis.")

      A Sample Password Grid

sample

      Here's how:

  1. Start by creating a set of several different grids patterned after the one above, with each square containing a randomly selected keyboard character. You can do this by hand, with a spreadsheet program, or with other software. True randomness is important here. Any software you develop to create grids should itself be encrypted and password protected by the grid currently in use.

  2. Choose and memorize an ordered pattern of squares. The longer the pattern, the more secure it is. Here are some examples using sixteen squares:

    sample pattern 1sample pattern 2sample pattern 3

  3. Follow your chosen pattern through the grid to read out your password and enter it into your password protected system.

    For example, consider the following grid:

    sample

    • Using the first pattern, the password is "6FVJ1vZ%n^dTpCeq".
    • Using the second pattern, the password is "eHYJVF6ixASvOcn%".
    • Using the third pattern, the password is "s@S1DjpTdQ3gnODY".

  4. Carry a copy of the grid with you. A spare copy may optionally be kept in a safe place, but in no event should a copy currently in use be stored anywhere near your computer - not even in the same building.

  5. In the event you find yourself beginning to remember parts of your password, switch to another grid and read out your new password, using the same pattern that you memorized before. There's no need to change to a new pattern. Change the password on your system to the new one.

  6. In the event that your system is compromised and you wish to destroy the data so that nobody, not even you, can ever recover it, simply destroy all copies of the current password grid. Keep unused copies in order to demonstrate to interested parties that the password is truly lost forever.

  7. Update, added May 28, 2007: For convenience, you can restrict the characters used in the grid to the 24 lower-case letters excluding "l" and "o", and the digits 2-9. This leaves a set of 32 characters which can all be typed one-handed while holding the printed copy of the password grid. It also prevents confusion of the digit "1" (one) with the letter "l", and the letter "o" with the number "0" (zero).

    Restricting the characters to this set and using a total password length of 16 characters, with each character being randomly chosen and duplicate characters being allowed to occur as they may, this results in a total of 2^80, or 1,208,925,819,614,629,174,706,176 possible passwords. This implies that without possession of the password grid, password strength will remain extremely strong.

(End - Page last modified on 3/3/2009.)