Halloween : Got a treat for me ?

Last Halloween I was out walking the dogs - this guest too - when a passing nubile wench commented "Handsome Son of a Bitch". Sadly, she wasn't talking about me, so no trick for her und no treat for me ;-) Have a happy halloween today anyway, folks:-)

Oh by the way, it was on October 31st 1517 that Martin Luther nailed his 95 theses to the cathedral doors, the start of the Reformation. Just to remind you Protestants of your roots. Not that the Papacy or the rest of Catholicism cleaned up their act tho' :-(

Copyright ^© Stu Savory on October 31, 2008 permalink Comments Email

I bought this motorcycle (an FJR1300) 6½ years ago. In the Brilon hills yesterday the mile-o-meter clocked up 80,000 kms (=50,000 miles). It has never broken down on me! Legendary Yamaha reliability. Sure, it has had minor troubles, but none that left me stranded. Otherwise, just regular maintenance needed :-) When you compare that with what (Brit) bikes were like 40 years ago. OMG! Or even the TL1000S I had before this one; the TL1000S was in the workshop SIX times for unscheduled maintenance:-(

So, a big THANKYOU today to Yamaha. Well done!

The FJR has its next inspection scheduled next week. I fully expect NO surprises and that it will do another 80,000 kms without any major problems. Way to go! :-)

Copyright ^© Stu Savory on October 30, 2008 permalink Comments Email

Yet another book to my name :-)

And it was as easy as falling off a (b)log!

A couple of decades ago I wrote some textbooks and co-authored and edited a couple of collaborative technical books. I also wrote a (pretty lousy) novel - in English - and a collection of short stories - in German. But, research papers aside, I haven't done a book recently. But this was just a little project to make a gift for some friends.

Calling it a book is pretentious! It's basically just a photo-album, commented with shared memories. A combination of vanity publishing and printing on demand :-)

A German company called cewe ( their web URL is www.cewe-fotobuch.de ) offers this printing-on-demand service online and offline. So I went into a digital-photo-gear store in a nearby town's shopping mall and picked up their (free) SW CD. Installation under Windows was fast and painless. The (German language) SW is fast and painless too. You just drag and drop photos from your hard disc into their directory, WYSIWYG positioning them and sizing them however you like. Their SW will warn you if the resolution gets too low, letting you shrink the photos again. Add as much text as you like, wherever you like, in their one fixed font. Anywhere from 26 to 98 pages in steps of 8 possible. I used some 60 photos in a 42 page 'book/album' (21cm square).

Finally, you choose what kind of cover you want, what photo(s) you want on the cover, add your name and address for billing purposes and save the results. You can then send all this to them online, but I chose to burn a CD and hand it in at the mall. After about a week, your thin but glossy book is delivered (or can be picked up at the mall). Quantities start at 1 and go on up. Reordering possible for 3 months, thereafter re-submission is necessary. They have streamlined the process very well indeed :-)

Did I mention you have a choice of formats? Small (13 by 14 cms), square which is 21*21cms, large (21*28 cms) and XL (30*30cms). People with hi-res pix (8 megapixel and up) could even do a coffee-table book. My 42 page album cost me just 34 € :-)

No, it does not have an ISBN number, and no, only I can order further copies. But on the other hand the total effort was under 8 hours including driving to the mall twice. So this is a great idea for making individual Xmas presents for friends with whom you share memories. Alternatively, you could do a 2009 calender with only 12 photos :-)

Update : Peter Harris points us to the similar Blurb site, which is in English. Thanks!

Copyright ^© Stu Savory on October 29, 2008 permalink Comments Email

YA CRAP

It doesn't just have to be petty embezzlement (see my earlier post from sunday of this week), it can be full-blown bribe-acceptance too. And on SEVEN counts!

Senator Ted Stevens (Rep., Alaska) was convicted monday of seven counts of making false statements on Senate ethics forms to hide hundreds of thousands of dollars in gifts and work on his Alaska home from an oilfield contractor at the center of a corruption investigation in the state, CNN reports.

Copyright ^© Stu Savory on October 28, 2008 permalink Comments Email

Happy Birthday, Uschi !

A round-number birthday is always something special. Here's wishing you (and Hans-Peter) many more of them, in good health, and knee-deep in bulldogs :-)

Copyright ^© Stu Savory on October 27, 2008 permalink Comments Email

The empress's new clothes :-(

I never cease to be amazed at the sheer stupidity and embezzling greed of the Ailin'-McPain GOP campaign for the US elections. This last week there have been half a dozen choice items on how to lose popularity with your potential voters:-

• The Republicans broke federal campaign laws by buying Sarah Palin and her family about $150,000 in clothes for campaign appearances, including $75,062 at Neiman Marcus, $41,851 at Saks Fifth Avenue, $4,902 at Atelier New York, $4,397 at Macy's and $5,103 at Bloomingdale's. Of course, none of the new clothes increases her ability to answer even the simplest questions, such as "What does a VP actually do?", she got it wrong again! Lipstick on a pig, indeed!
• As governor, Palin charged the Alaskan taxpayers for nights spent in her OWN home and for travel expenses for whole family. The governor’s daughters and husband charged the state $43,490 to travel, e.g between Wasilla and Juneau, so they wouldn't miss their mommy. Or perhaps get pregnant while mommy was out of the house? A six-pack of rubbers would have come (sic!) cheaper!
• Inserting a stupid guy (Joe the Dumber) to ask Obama a question (which he answered excellently, BTW) and then sacrificing him to the media. Turns out 1) he wasn't called Joe, 2) he wasn't a legally licensed plumber, 3) he lied about his income (saying 250K$ instead of 40K$, 4) he would actually benefit from Obama's tax cuts 5) he claimed to be against all socialism, but told us about how his whole family lived from social security benefits earlier in his life etc etc.
• Anger management issues appear to run in the McPain family. This week we had his brother (yes, he actually IS called Joe) calling 911 just because he was stuck in traffic. Here you'd get a ticket for 'wasting police time' for doing that!
• The highest paid person in McPain’s campaign this month is Sarah's "Amy the Hairdresser". She was paid $22,800 for the first two weeks of October alone! And these are the GOPers who rabbit on about John Edward's $400 haircut?
• Sending a begging letter to the Russian embassy for a campaign contribution. Sounds patriotic, as in "country-first" ;-) Or maybe they just chose the 'red-state' embassies that Palin could see from her doorstep?

Enough, already, I feel sick (again)!

PS : And if you were wondering about whether today's title was metaphorical or not, be aware that in Las Vegas the strippers are now competing in a Sarah Palin Lookalike show... WTF?

Copyright ^© Stu Savory on October 26, 2008 permalink Comments Email

The downside of your steak :-(

Hamburgers and steaks both taste great, but at what ecological cost? :-(

Worldwide meat production has doubled since 1970 from 130 to 260 million tons annually. Just looking at the cattle : Each and every cow drinks well over 100 liters of water per day. 250 liters of water for every kilo of meat produced. She needs almost 50,000 liters of water to produce her 10,000 liters of milk annually. And she consumes 77 million tons of feed to produce the 58 million tons of meat.

Now let's consider atmospheric pollution : The average cow farts every 40 seconds, that's 2000 methane farts a day, totalling 235 liters of methane which is a worse greenhouse gas than carbon dioxide by a factor of twenty. So each and every cow pollutes the ozone layer as much as a small car. Eleven percent of the greenhouse effect is due to cattle's methane; more than all the world's traffic put together.

Now let's consider the grazing area needed : Grazing ground takes up almost a third of the world's ice-free surface, because there are more than 1,400 million cattle around the world. Brasil alone has 200 million cattle. To get this grazing area South America felled 10,000 square meters of rainforest every single second! To put it another way, every single hamburger you eat caused six square meters of rainforest to be felled :-(

Now let's consider market distortion by subsidy : It's not just South America's fault. The EU subsidises agriculture to the tune of 46 milliard Euros every year, that's about 800 Euros per cow. No wonder third world farmers can't compete with EU prices.

So the next time you go get a polystyrene-boxed convenience burger, think about that. And this : Why do you seldom see blind people in the mall eat at the burger-fry? Maybe because they're not sure if they can tell when they've got through to the box?

And the moral of my story today? You too have a steak in the future of the planet ;-)

This pun is dedicated to Jams, who seriously believes he can make worse puns than I do. No chance, Jams!

Copyright ^© Stu Savory on October 24, 2008 permalink Comments Email

Out of the blue :-)

Yet another generous blogreader!
Doctor C42 knows I fly aeroplanes, so when he found this 1936 pilots' training manual from his schooldays as a 9-year-old aviation enthusiast he decided to send it to me. Thanks, man, I'm overwhelmed by your generosity!

Knowing that Doctor C42 is also an avid motorcyclist (he has a couple of Triumph triples) makes it easy for me to thank him. I shall send him a signed copy of the motorcycling novel I wrote nearly 20 years ago, punnily entitled Howl of the Mountain King.

That'll teach him to be so generous! ;-)

The aforementioned pilots' manual was published by the then extant German-American-Petrol-Company Stanavo; afaik this is now Standard Oil. Nicely non-political, the only political bit are the restrictive rules and regulations about flights abroad (pp53-60). The technical stuff about e.g. reciprocating engines, meteorology and flight itself are as valid now as then. But what I really like are the old-style B&W pics :-

Copyright ^© Stu Savory on October 22, 2008 permalink Comments Email

Double Hubble Trouble :-(

S ome of the most spectacular astronomical photos ever seen were taken by the Hubble space telescope. Hubble has been going now for 17 years already. The Hubble space telescope's 17 years' worth of observations have produced more than 30 terabytes of data! That's about 800,000 observations and 500,000 images of more than 25,000 celestial objects. Go peruse the Hubble galleries of astrophotos.

But recently the original data transmission channels (called side A) failed. Hubble could still collect data, but not forward it to Earth. However, Hubble was designed with built-in redundancy, so there is are side B data transmission channels too. NASA attempted to command a switchover to side B yesterday, but there appear to have been two glitches in the switchover. I quote from the NASA status #4, datelined October 17th:-

"The reconfiguration proceeded nominally and Hubble resumed the science timeline at Noon ET on Thursday, October 16. The first activities out of that on-board science timeline were the commanding of the science instruments from their safe to operate modes. This occurred nominally for Wide Field Planetary Camera 2 and the Near Infrared Camera and Multi Object Spectrometer. However, an anomaly occurred during the last steps of the commanding to the Advanced Camera for Surveys. At 1:40 pm, when the low voltage power supply to the ACS Solar Blind Channel was commanded on, software running in a microprocessor in ACS detected an incorrect voltage level in the Solar Blind Channel and suspended ACS. Then at 5:14 pm, the Hubble spacecraft computer sensed the loss of a "keep alive" signal from the NASA Standard Spacecraft Computer in the SIC&DH and correctly responded by safing the NSSC-I and the science instruments. It is not yet known if these two events were related? The investigation into both anomalies is underway. All data has (sic!) been collected and is(sic!) being analyzed. The science instruments will remain in safe mode until the NSSC-I issue is resolved. All other subsystems on the spacecraft are performing nominally and astrometry observations continue."

I sure hope they can get Hubble up and running again! (Crosses fingers ;-)

Copyright ^© Stu Savory on October 20, 2008 permalink Comments Email

A Predilection for Puns

Funnily enough, there seems to be an increasing number of terrible puns in the blogosphere recently, something very much to my taste :-)

Over at The Poor Mouth, Jams kicked off with

"A Bilbao restaurant was recently prosecuted for infringing 
fire precaution rules - the restaurant only had one way out.

The Judge when passing sentence warned the owner that 
he should never put all his Basques in one exit."

"That's as bad as the one about those persistently obnoxious French 
gays who insist on using a crusty baguette as a sex toy.

They're a pain in the arse" ;-)

"I've often wondered how the Palins got to have so many kids, since 
- like most Alaskans - they don't like to get bear in the house" ;-)

It must have been in 1986, when I was working in the Silicon valley and San Francisco area. It was a 'casual friday', but Gloria, our raven-haired secretary had arranged for me to do a fleeting guest appearance on MTV's show Andy Warhol's 15 Minutes as a European AI researcher visiting Stanford. We had agreed to meet as usual after work in a local bar for 'happy hour' before going home for the weekend. Gloria as usual commuted on the B.A.R.T (Bay Area Rapid Transit) to and from San Fran, but I rode my motorcycle over to Half Moon Bay, where I was staying. At the '15 Minutes' TV studios I had heard that there was going to be a BART strike at the start of the next week, so I knew I had to warn Gloria, so that she come to work by car. As she came dashing into the bar, dying to find out about the TV show, she shouted her question across the room "So how was your TV appearance, Stu?". But I was thinking about the forthcoming monday's BART strike and warned her "Sick Transit, Gloria, monday!" ;-)

Copyright ^© Stu Savory on October 18, 2008 permalink Comments Email

Overview of the Numbers

D own at the pub, I had just said "all those different kinds of numbers", when Dorte asked for clarification, because she "didn't know how they all fitted together". Here's a set diagram, while I explain the different types of numbers.

Working from the inside outwards, we have :-

• The natural numbers : {1,2,3....}, as used for counting things.
• Whole numbers : include zero, thus {0,1,2,3....}.
• The Integers : include negative naturals, thus {...,-3,-2,-1,0,1,2,3...}
• Rational numbers : what you get when you divide two integers P/Q (but Q may not be zero). Examples are 1/2 or 2/3 or 355/113 (recurring decimals allowed).
• Irrational numbers : Real numbers which are NOT expressible as a fraction. Examples are PI and root(2) and e. There are NO repeating patterns in their decimal representation or indeed a representation in ANY natural base.
• Real numbers : = rationals and irrationals. The coordinate of a point on a line.
• Imaginary numbers : product of a real number and the square root of -1 (shown as i). Thus (3i)² = -9. Disjoint from the real numbers.
• Complex numbers : have two parts, a real and an imaginary part; thus A + Bi. The coordinates of a point in a plane. Here's how to do complex number arithmetic.

Copyright ^© Stu Savory on October 17, 2008 permalink Comments Email

Highway to Hell

On a more positive note (sic!), AC/DC are back on tour again and will be touring in Germany in early March 2009. But all tickets were sold on saturday within 12 mins :-(

So here's an older YouTube video of them instead...

Copyright ^© Stu Savory on October 15, 2008 permalink Comments Email

Size matters ;-)

The longest human penis ever measured was 48.3 cms long. About 5000 men worldwide have a penis of 30 cms or more (most of them seem to be employed in the p0rn industry). Women find 18 cms the most pleasant size; btw, the largest clitoris ever measured was 12 cms long. The longest condoms made are 21.5 cms long. When condoms for the UK troops were made in WW2, some were made in 18 inches instead of 18 cms due to the manufacturer misreading the order. Rather than waste them, Churchill ordered them labelled small and Made in Britain and shipped to the USA ;-)

Sigurður Hjartarson has a penis over a meter long and weighing 75 kg (I've known girls who only weighed 2/3 of that!). But that's because Sigurður is the curator of the Icelandic Phallological Museum (Hið Íslenzka Reðasafn) in Húsavík, Iceland and it is a Sperm Whale´s penis. So when you get spams offering you a 25 cm penis, reply that you refuse to cut any off, or to let a mohel chop the end off. Of coarse(sic!), in Yorkshire(UK) they just take the lads up t'mill and have the end ground off painfully at t'mill-wheel (which is why it's called the Brit miller^* ceremony there) ;-)

^*That´s my Hebrew pun, OK? Brit milah (Hebrew literally means "covenant of circumcision" ;-).
I made it up already for Elisson, who was looking for Hebrew puns; sorry man, yes it is terrible.

Copyright ^© Stu Savory on October 13, 2008 permalink Comments Email

Lookalikes ?

. . .
Miss Wasilla 1984 (Sarah Palin) . . . . . . Marcy Darcy (Al Bundy's neighbour)

I apologise to actress Amanda Bearse for noticing this unfortunate resemblance ;-)

In the meantime, here's some more food for thought: as long ago as 1935 the famous American author Sinclair Lewis, the first American to be awarded the Nobel Prize in Literature, wrote these far-seeing and predictive but ominously frightening lines :-
"When fascism comes to America it will be wrapped in the flag and carrying a cross."

. . .

We are reminded that one of the characteristics of Fascism is the abuse of power :-(

Copyright ^© Stu Savory on October 11, 2008 permalink Comments Email

Autumn leaves

The trees in autumn are so breathtakingly colourful . . .

This post is for the three ladies who have complained that this month's blog has been far too geeky in every single entry this month, and could I do simpler stuff again? :-)

Now what do autumn leaves have to do with blogging, you might well ask?
Percy Bysshe Shelley (1792 - 1822) put it like this in his poem Ode to the west wind :-

What if my leaves are falling like its own?
The tumult of thy mighty harmonies
Will take from both a deep autumnal tone
Sweet though in sadness. Be thou, Spirit fierce,
My spirit! Be thou me, impetuous one!
Drive my dead thoughts over the universe
Like withered leaves to quicken a new birth!
And, by the incantation of this verse,
Scatter, as from an unextinguished hearth
Ashes and sparks, my words among mankind!

Mind you, poetry aside, I generally prefer the stuff his wife wrote ;-)

Copyright ^© Stu Savory on October 10, 2008 permalink Comments Email

DIY : homebuilt CSP845/M-138 cipher device

Construction : Strips of balsa wood bought from a modelling shop, mounted on a plywood sheet found in my workshop and cut to size. Mixed-up alphabets - like those mentioned on monday - are written on the strips (twice, because unlike monday's discs, they don't wrap around). Line guides are glued left and right on the plywood base and act as constraining borders. Photo (left) shows you the overall view of it.

In the photo on the right I am pointing to the strip which corresponds to disc 17 of the US Army's M-94 cylinder. As you can see - reading from the top down - that strip 17 begins "ARMYOFTHEUS". The strips hold the same mixed-up alphabets as the discs did in the history section of the article I wrote on monday (go back & read it, maybe?).

Usage : Each strip is identified by a single letter written in red. Put the strips on the board using the key sequence of letters from the daily chart (or key phrase, or session key depending on the pre-agreed key-selection method). This sequence is the key. Slide each strip up or down to get the cleartext of your message on line 1. As shown below, the cleartext is the same as I used in monday's article "I know you all and will awhile uphold the unyoked humour of your idleness". Choose any other line (say line 13 here) and copy off the ciphertext for the first 25 letter block. Here it is HGHTV etc. Repeat for as many blocks as are necessary for your message, choosing a different encoding line (i.e. not 13 etc) for each block of text encoded.

The recipient decodes by placing the strips on the board in the same (daily?) sequence. Then he slides each strip up or down until the received ciphertext is on line 1. Whereupon the plaintext will appear on one of the other lines (the rest will contain nonsense). Sliding each strip up or down is equivalent to rotating each disc of the cylindrical M-94 which I showed you on monday.

The CSNMPA ( = USS Pampanito in San Francisco) have a good page on the historical CSP 845 strip cipher, they also have a copy of the original instruction manual. BTW, the equivalent US Army device number was M-138. Was that understandable, Kevin?

PS : Chip sounded a little paranoid about using this crypto stuff, but he does live in a repressive police state after all ;-) No, folks, the crypto stuff I'm showing you here was declassified back in 1996, a dozen years ago. In fact, you should be able to break these codes in a couple of hours using only pencil and paper & lotsa brainpower :-)

PPS : In view of annoying past experiences, please do NOT send me pieces of your own ciphertext to decode for you, because I'm not in that business and you may just end up pissed off at me (YMMV) for refusing to help :-) Been there, done that :-(

Copyright ^© Stu Savory on October 8, 2008 permalink Comments Email

DIY : my homebuilt M-94 cipher device

Many of my blogreaders will know of my interest in cryptography , that is, codes and code-breaking. There's a hint in the About paragraph below my photo in the sidebar and there are a number of pages (albeit in German) about DIY (Do It Yourself) amateur codes. Most of the codes shown there are not particularly secure and are easily broken. Today I want to show you a simple wooden device which is a bit more secure; the key-length is about 84 bits. It looks like this :-

Construction : First off I put a piece of wood (actually an old branch from my cherry tree ;-) in a lathe and turned 27 discs to the same diameter. Turn a cylinder then cut it into discs of the same width. Then I labelled 25 of the discs on the sides with a letter A through Z. Actually I left out J, there is a cryptological reason I wanted 25 instead of 26, but let's skip that here. Then I measured the circumference of the discs and divided the circumference into 25 equal-sized cells. Into each cell I wrote a letter of a mixed-up alphabet. The letters are all written in black except the red one which labels the disc (on each side). These colours are for demonstration purposes only.

I got the mixed-up alphabet by drawing the 25 letters one at a time from a Scrabble set hidden in an opaque bag. This is because we humans are terrible at generating random sequences mentally. Actually, local schoolchildren who were involved in this code-project helped do this task for me :-) Then we used a PC to check that none of the mixed-up alphabets correlated significantly with the others. Those which did were discarded and a new mixed alphabet drawn out of the bag. This was probably the only step that schoolchildren could not understand, but it is cryptologically necessary that the 25 discs contain independent mixed-up alphabets (lest the key be shortened and the code thus weakened). So disc X - below - shows what the different discs look like.

The other two discs´ cells I labelled 1 through 25 around their perimeter. These are end-discs merely used to align the letters into lines. Of course a real M-94 - made of metal - has indentation pawls and an alignment bar, hard to do in wood :-(
Oh, BTW, while the cylinder was still in one piece on the lathe I had bored a bolt-hole down the centre. This bolt lets me mount the discs and secure them with a wing-nut. Cryptic Joke : the wing-nut is over on the far right as usual ;-)

Now I can mount the discs on a nine inch long bolt I had kicking around the workshop. For demonstration purposes only the [red letters labelling the] discs are shown here mounted in alphabetical order. This is not something you should usually do! ;-)

Note that since the 25 discs all have different mixed-up alphabets, the other lines show mixed-up ciphertext too. Where line 1 shows the plaintext ABCDE FGHIK LMNOP QRSTU VWXYZ, line 2 shows a ciphertext BAZCM KSPVE YNCDB NMDOT NVKPD. Moreover, line 3 shows a completely different ciphertext : CCIBZ etc. However the many adjacent As in line 25 tells us that 16 of the 27 children 'helping' me had not really understood about drawing letters from their bags at the beginning of the mixed-up alphabet generation process. Or, I had explained it badly. Shit happens ;-)

You will need to build several identical devices, one for each intended user.

Usage : Now let me explain a very simple way to use this M-94 cipher device. There are more sophisticated ways to use it which are designed to defend against various codebreaker attacks. But for explanation purposes only I'll show you one simple way.

Using a daily table of randomised alphabets previously distributed to all users of this M-94 system (in this case it was the class of schoolchildren) you mount the discs on the central bolt so that the order of the discs (i.e. the red letters) is the sequence shown for that date in the table. For October 6th 2008 this might be QWERT ZUIOP ASDFG HKLYX CVBNM (that´s a pretty stupid example; do you understand why?).

The sequence of the discs on the central bolt is the key used that day.

In a more sophisticated approach I would generate individual session keys, geeks will understand why, but I want to keep this example as simple as possible ;-)
Geeky DIY exercise : describe a procedure to generate individual session keys.

So there are factorial(25) different keys. This gives a key-length of about 84 bits.
That having been done, and the wingnut loosened off so that I can turn the discs individually, I set up the plaintext to be encoded on line six. Here I have chosen an appropriate line from Shakespeare´s "Henry 4th; Part 1" where Prince Hal says "I know you all and will awhile uphold the unyoked humour of your idleness".
The first 25 letters are in line six below. Repeat as needed to get the whole message.

Now choose ANY other line and read it off as the ciphertext. For example line four would give the ciphertext CFZRS NVNCK EWEAX TBZZN NDFSD. Make a note that you have used line four and do not reuse it for another block. Had you used line fourteen (as shown below) you would have got a different ciphertext for the same plaintext, viz: HGWXF KFHTM NCKHA CFUGU FZSDI.

Decoding : The recipient of the message also uses the same daily table of randomised alphabets previously distributed to all users of this M-94 system. He also mounts the discs on the central bolt so that the order of the discs (i.e. the red letters) is the sequence shown for that date in the table. This is known as key-setting. He then sets the ciphertext (HGWXF KFHTM NCKHA CFUGU FZSDI) onto an arbitrary row, let´s say row two (I´m now using the index disc on the right of the cylinder, as shown above). Tightening the wingnut to prevent the discs from slipping he now just rotates the cylinder until he finds a line that makes sense (i.e. plain English in this case). As shown below, line nineteen (using the index disc on the right) shows the plaintext. Eureka!

History : Past US president Thomas Jefferson (1790) had a version with 36 disks, based on something he had seen during his stays in France (i.e. he didn't invent it himself). French Commandant Bazeries (1891) made one with 20 discs. US cipher expert Colonel Parker Hitt (1914) built a topologically equivalent strip device. I have built one of these too, to show schoolchildren that they are but variants of the same machine and topologically the same. The Russians used a strip version during WW2. Strip versions (like the CSP 845) are impractical for use in the field; the cylinder version with the locking nut can be used e.g. in a tank that is in motion over rough terrain. In 1917 Joseph 0. Mauborgne of the U.S. Army signal corps had the same idea. As late as the mid 1960s the US Navy employed a version which they called the CSP-488. But then they were still using Playfair ciphers in WW2 although they can be broken using just pencil and paper, even by a bear of very little brain (e.g. me ;-) Pooh!
In fact John F. Kennedy used a playfair cipher in WW2 on his PT-109 boat.

The military M-94s (=CSP-488s) are made of metal and half the size of mine. I built mine twice the usual size because I use it for lectures and demonstrations. They also have an indenting mechanism so that the letters line up properly and an alignment bar to aid reading off a row. Mine - being made of wood (total effort only a couple of hours) - is not so sophisticated ;-) I also made up my own mixed alphabets (well, the schoolchildren did) to avoid any copyright/interchangeability issues. US military versions of the M-94 are recognisable by the mixed alphabet on disc 17, which reads "ARMYOFTHEUSZJXDPCWGQIBKLNV" ;-)

The 25 discs of my copy and the original M-94 share the disadvantage that numbers would need to be spelled out and that there are no punctuation marks. The WW2 Enigma had the same problem. Also, the instruction manual might need to contain a list of approved plaintext abbreviations, maybe different for army/navy/air force/etc.

Capture situation : In a military situation, precautions would need to be taken to avoid an enemy capture of the cipher system. First off, whenever the device is not being used actively, remove all discs from the bolt and put them back on in e.g. alphabetical order. This way, the most recently used key is protected from discovery. If your capture is imminent, the three components need to be destroyed. Army procedures might include burning the key tables (sheet for sheet, individually) and the usage-instructions, then taking the discs off the guide rod and blowing them up with a grenade (that was the procedure for e.g an M-209). Navy procedures might include just throwing the (metal) CSP-488 overboard into deep water. Obviously this wouldn't work for my wooden version ;-) Don't know the submarine or aircrew procedures.

Security : Now I did mention that the keylength is some 84 bits which makes it pretty secure. However, given enough ciphertext (and/or cribs) it is possible to cryptanalyse the M-94 class of cipher devices. Admittedly it takes time and you have to know what you are doing, but if I can do it, you can be sure the professional codebreakers can do it too, faster and with more elegance. So don´t let me see you using it for other than tactical uses or for teaching or demonstration purposes ;-) And for obvious reasons I am NOT going to tell you how to cryptanalyse an M-94. That´s your DIY project ;-)

The picture below shows yours truly demonstrating my homebuilt M-94 cipher device during the HNF crypto-exhibition several years ago. Kids & dads get fascinated :-)

What is an M-94 worth? Several declassified original M-94 cipher devices have been sold on eBay for about $7,000 each. So you see, it is cheaper to build your own ;-)

Caution : It may be illegal in some countries for you to build cipher devices yourselves or use them. In fact it may have been illegal for you to read this blog! Shit happens ;-)

Other M-94 pages : from the following 10 authors...

• Bob Lord
• Brooke Clarke
• CipherClerk
• Cryptologia, Vol 1, Nos 1 and 2
• Dirk Rijmenants
• Friedrich Bauer's book "Decrypted Secrets"
• Jerry Proc
• NSA Museum
• San Francisco Maritime National Park Association
• Wikipedia M-94 page.

Comments : (9)
Mark Baldwin wrote :

 Have had a quick look at your blog re M94.
 Seems fine in principle, but would make a couple of minor comments>>
 1) It looks as if you have a unique cherry tree, 
 as the disks seem to be made of plywood!
 2) If you were to thread the full set of blank discs onto the bolt, 
 and clamp up, and THEN draw 
 the 25 lines across the whole set to define the 25 compartments, 
 I think you could get a neater looking result, provided you took 
 care to do the division into 25 accurately.
 Otherwise great! And anything which gets the kids interested must be good.
 Well done!

Dirk Rijmenants wrote :

 Great stuff! This is probably the first ‘green’ crypto device ever ;-)
 I’ll send it to cryptocollectors, 
 maybe you’ll get a fortune of this new style eco crypto.

Sterling (Chip) Camden wrote :

 Very cool, Stu.  It will be linked.
 I found the encryption/decryption steps just a little bit hard to follow, 
 though I made it through OK.  
 Perhaps more step-by-step pictures would be illustrative.

Jaqueline wrote
Your little wooden cylinder would probably be illegal here in France ;-)
Off Topic : OMG, I just clicked on the button on your sidebar !

Ole Phat Stu answered :
The photo behind the button is changed every week, Jaqueline, so click it regularly ;-)

Kevin wrote

 Can you show us the equivalent strip version that you mentioned?

Ole Phat Stu answered :
Tomorrow, OK, Kevin? I have to photograph it first.

Copyright ^© Stu Savory on October 6, 2008 permalink Comments Email

Cheating Tosser!

Today I'm going to show you how to toss a biased coin fairly.

To get some context, let's assume that the US election results come out as a draw and the result is to be decided by coin tossing. Karl Rove pulls out a coin and, turning to McCain, says "You call first, John". Now Obama is pretty damn sure that Rove has a biased coin and that McCain knows what to call. So how can he ensure a fair result (50:50 chances) despite the coin being biased in an unknown way? You can be damn sure Rove isn't going to let him conduct a series of 20 or so tosses to test for bias, because that would make it plain that he (Rove) was cheating (as usual).

Of course, Obama could insist on calling first. But then Rove would think that he (Obama) had managed to substitute the biased coin with another biased coin (because that is what Rove would have done). So we're looking for a method of tossing a biased coin to get a fair result despite not being allowed to test for any bias beforehand.

Here's how :-

Toss the coin twice. If it comes up Head-Heads or Tails-Tails toss twice again until getting differing results. Any contestant - it doesn't matter which - can call first. Let's say he predicts Heads-then-Tails. The other contestant then is assigned Tails-then-Heads. This is a fair tossing scheme! The chances are 50:50 as desired!

Example : Assume Rove's coin is biased 70:30 in favour of Heads, instead of 50:50. The chance of getting two Heads in succession is thus 70%*70% = 49%. The chance of getting two Tails in succession is thus 30%*30% = 9%. Total so far 49+9=58%. But both these results are ignored until two different toss-results appear. The chance of getting Heads-then-Tails is 70%*30% = 21%, and the chance of getting Tails-then-Heads is 30%*70% = 21% also. Total of these = 42% as expected (100-58%). You can plug in any percentage bias you like, my method always delivers a fair result.

Notice that the chance of Heads-then-Tails is the same as Tails-then-Heads! So my method gives a fair toss (50:50) despite the coin being biased in any way :-)

Copyright ^© Stu Savory on October 3, 2008 permalink Comments Email

You have Mail !

Since when?

The everyday You have mail! pop-up got me thinking about the history of mail. Probably the oldest letter mentioned in historical records (a recorded delivery, as it were ;-) was from King Hammurabi (1728 BC to 1686 BC). Letters presuppose that someone at each end can read and write. Previous exchange of short messages was by voice-mail where the messenger had to learn the message off by heart. Thus he could be tortured to tell it if captured. Hammurabi's letter would have been delivered by a messenger who could NOT read or write and who had been instructed to destroy the letter if capture was in the offing. These messages were inscribed on clay tablets and were effectively postcards, open to (il-)literate eyes.

In seafaring times, sailors would leave written messages in known locations (store-and-forward) in the vague hope that someone sailing in the other direction would pick them up and take them back home to their loved ones. Needless to say, most such letters got lost. Around this time, envelopes were introduced, so addressing was separate from content which could thus be hidden from prying eyes. Wax-seals showed any evidence of tampering. By comparison, Emails are postcards :-(

Widespread literacy came about as a result of the printing press. So people who could read and write wanted their own message exchange system. Organised postal services, picking up everyman's mail from public sets of collecting mailboxes, forwarding to a sorting centre and distributing to addresees (or their private mailboxes), began to appear in the 17th century. People in Paris (France) in 1653 could buy paper strips to pay for 1 unit of delivery. Stamps were introduced then, gummed versions came much later. French stamps were flavoured nicely too :-)

Registered mail - i.e. proof of delivery - appeared AFAIK in the following century.

And to what lengths we now go to achieve this 'letter' functionality for our electronic communications! Digital signatures, encryption, public/private keys are needed to achieve secure end-to-end communication. More about message encryption later this month. But the truth of the matter is that most people still continue to use simple Emails (as open as postcards), liable to forgery, phishing, and no proof of delivery :-(

For an amusing account of the introduction of postal services, I can recommend Terry Pratchett's excellent novel entitled Going Postal, the ISBN number is 0552149438.

Relevant joke: What was Mae West's favourite pop-up? "You have male !" ;-)

Copyright ^© Stu Savory on October 1, 2008 permalink Comments Email