I contribute to an Open Source PGP-related project, for which I also do user support on a forum and mailing list.

I remember an user saying that he was not going to use PGP but a symmetric cypher instead. The reason? “In asymmetric cryptography, you have to disclose part of your key to others (your public key), while in symmetric cryptography you keep the key all for yourself. Hence symmetric crypto is obviously safer than asymmetric crypto.”

Another user complained about the hassle of keeping a secret key AND remembering a password, and proposed that keyservers should also store private keys…

]]>“Just to be clear, I assume you still generate the letters or numbers with the dice…”

Yes, the comp program is just for “pretty printing” (and displaying a running count/frequency graph as a confidence assurance).

However… I did some time ago look at using a “card shuffling” algorithm similar to ARC4 that continuously as an evolving pool of pesudo randomned and every so the output of a low frequency true random generator would add jitter to the card shuffling algorithm to “spread the love” of the entropy across the evolving pool.

It turns out that if you keep the sampling rate from the pool to less than half the sarray size multiplied by the average frequency of the TRNG it’s statistics are very simillar to that you would expect from another TRNG…

Asside from all the philisophical questions over what is and is not a random sequence, you have to ask yourself ‘if it looks like a duck quacks like a duck do I realy need to treat it like a goose?’

So yes I have considered rewritting it to do this…

Beside a few “quantum gismos” (mixing a microwave noise source with a very delayed version of it’s self) to get wide band “base band” noise for random bits, we realy do not have good “fast TRNG’s”.

And the price of these quantum gismos was/is extraordinarily high when compared to say a ‘reverse biased diode junction’ or even high level AWGN ‘excess thermal noise’ source….

With regards,

“Do you worry about the dice being imbalanced? Have you tested these particular dice?”

Yes and Yes.

As I said the method I mentioned is for “Rough and ready” low volume small size OTPS, where the inherant bias of a pair of reasonably priced die will be to small to measure.

However my jam jar actually has six dice in it with two sets of three dice, one set with black spots and the other with white spots and I take the resedue mod six of both sets when using them (which I can do almost at a glance by “striking out “sixes”).

Prior to inclusion in a set, each die had a 240 (40 from each face) roll plot done and I started with ten of each die type. The die in each set were selected to give the best balance based on it’s plot.

However I’m still cautious hence the running count tally in the software.

With regards,

“Have you considered moving to polyhedral dice? Some of thos operations might be easier with ten- or twenty-sided dice”

I actually had a pair of twenty sided dice made for those doing mathmatics, they were expensive and showed measurable (with a micrometer) asymmetric off set and hence bias (I have the workshop tools required for cutting, grinding, flanging and measuring X-band and above waveguide).

You can actually get packs of tested and approved “Casino Die” for quite reasonable sums (I used to be a member of a “small club” and they quite happily sold me a fresh sealed box of them). However I prefer the mass produced half inch cube die with rounded corners you can buy these in bulk for next to nothing (ie 10-20 cents each).

]]>Do you worry about the dice being imbalanced? Have you tested these particular dice (I notice you store the jar, presumably with the dice in it, in the safe)?

Have you considered moving to polyhedral dice? Some of those operations might be easier with ten- or twenty-sided dice.

]]>US – the best idiocy money can buy

]]>“I know someone out there has released an alphabet die, so the biggest problem with OTP generation now is sourcing, and disposing of, the carbon paper you’d need to create the two sheets without using a copier.”

An “alphabet die” I’d like one as a “desk toy”, but you don’t need it.

All you realy need to generate a rough and ready OTP is two dice of the same size but different colours (or two dice of the same colour but ink in the spots on one) and a simple six by six grid.

You can make either a “letter” or “number” OTP with the grid.

For a “letter OTP” you fill the alphabet in five letters at a time in the grid rows (ie in the 1 to 5 columns and leave the sixth blank) in the first five rows. In the sixth row you put the Z in the sixth column.

To use first decide which die is for the columns and which for the rows (and stick with it for the entire time you make the OTP).

For each letter throw both dice and look up the intersect square, if it contains a letter write it down, if it’s blank (and it should be on average for 10 in 36 throws) just throw both dice again untill you get a valid letter.

For a “Number OTP” just put 1-5 in the odd rows, and 6-0 in the even rows giving you thirty filled spaces and six blank spaces.

Providing you are only making a small amount of KeyMat two dice are ok.

You will also find it’s a lot quicker if you can use a 1lb (454g) glass “jam jar” or other transparent container with a lid put both dice inside. Then shake it sufficiently hard with your non writting hand so the dice hit the lid and bottom three or four times and let them fall to the bottom. With a little practice you can get one letter or number every 4 or 5 seconds and can keep it up at that rate to write down a thousand letter pad on A4 paper (ie ten 5 letter groups every third line).

I do it slightly differently, I use a very old PC and a dot matrix printer and two part stationary, I wrote a small program years ago in Apple Pascal (later converted to turbo Pascal then Turbo C) where you just type in the letters or numbers one by one and it prints them out in a nice format (ie six five letter groups in three line boxes fifteen rows to a page with a serial number at the top etc) on two part fan fold stationary that is also punched for putting in a ring bound folder.

Surprisingly you can turn out about 15 pages an hour and a couple of days days work gives me a couple of hundred pages which is all the out station emergancy KeyMat I need for a year or so these days.

Importantly the printer “ribbon” goes back in the safe with the disk, jar and folder of printed fanfold or it goes out the back to the BBQ pit where it gets reduced to less than ashes.

One important thing to note with OTP’s in use, you need a piece of glass slightly bigger than your “pad sheet” to write on otherwise you could leave a tell tale impression (why do you think all ‘signals’ officers/ yeomen / asorted REMFs have glass tops to their tables, it’s not there just to hold down the photos or standing odrers ðŸ˜‰

]]>As for paper and pencil one time padding, I know someone out there has released an alphabet die, so the biggest problem with OTP generation now is sourcing, and disposing of, the carbon paper you’d need to create the two sheets without using a copier.

]]>I would have encryped it using 6ROT13 because that is twice as secure as Triple-ROT13. ðŸ˜‰

]]>