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Bring back these removable 10 inch disk packs - 1970s tech
http://www.nf6x.net/2014/03/da...

I remember a talk about Bletchley Park where I asked whether the germans had any codebreaking work. I still have not heard nor seen a word of it anywhere at all.

I read an account recently about German cryptanalysis of the US M-209 machine, which happens to be one of my favorites. I don't remember where I read it, though. I'll reply again if I find the link before my mind wanders too far. It is my understanding that Allied forces were aware that Germany could break the M-209 cipher, but used it for low-level traffic because the machine was so convenient for widespread field use, where we wouldn't want to risk capture of our higher level cryptosystems. Low-level tactical information often is only of value to an enemy for a short period of time; i.e., a message about a small troop movement that will happen in an hour isn't very useful the following day after it has already happened. Thus, if you believe that your enemy requires a day to break one of your codes, that code can still be useful for messages that would only be of value to them for a few hours.

If I recall correctly, Germany did do codebreaking work against the Allies, but didn't achieve the same level of success that the Allies did against their codes.

If you would like to try your hand at cryptanalysis of the M-209 and related machines, take a look at this ongoing M-209 Crypto Challenge. I solved the first problem in the series, but then had to quit working on the challenge because of other stuff that came up. I may go back and work through the other problems when I have some free time.

You can discount gibberish and orders for lamb chops if you are quite confident that the message was, for example, English text, and that "lamb chops" was not a code phrase for something like "crates of ammunition". But you still can't distinguish between "FOURTEENTH TANK BRIGADE WILL ATTACK ON NOVEMBER TWELFTH" vs. "EIGTH INFANTRY BRIGADE RETREATING WITH HEAVY CASUALTIES". In any case, code words, code phrases, abbreviations, jargon and spelling errors can all be reasonably expected in legitimate military and espionage communications, so without detailed inside information, you can't even discount a possible decoding like "RABBITS ARE RUNNING DUE TO CRITICAL LAMB CHOP SHORTAGES". For any given message length, it is quite possible to come up with possible decodings of the same length with exactly contradictory meanings. Thus, even in real life, an intercepted OTP message only gives you an opportunity for traffic analysis.

When properly implemented, one-time pad messages are truly unbreakable in the lab and in practice. Successful cryptanalysis of them is only possible when serious mistakes are made, such as using a single key more than once, using a key that can be predicted by some means, etc.

As an aside, Between Silk and Cyanide was an interesting account of one person's involvement in WW2 cryptography related to espionage operations. If we can assume the author's account is accurate, then there was a lot of WW2 espionage activity using ciphers other than OTP, and OTP (in particular, OTP using letters rather than numbers) was a later development in the war, still further delayed by the complications of distributing key material. So, it makes sense to me for cryptologists to have made an attempt at breaking this recovered cryptogram based on the possibility that some system other than OTP was used to encipher it.

Incidentally, five-letter groups of seemingly-random characters is a common form for enciphered text, and is not specific to OTP. It's conventional to break enciphered text into five-letter groups to make it easier to avoid losing one's place when transmitting it by telegraph or teletype. Cipher machines such as my US WW2 M-209B or my Soviet cold-war Fialka even automatically space the ciphertext out into five-letter groups. It takes actual analysis of a ciphertext to determine what system(s) may have been used to create it. For practical purposes, there will often be information called "indicators" embedded in the ciphertext, so that a busy cipher clerk will know which machine to use and which key to load into it to process that message. There are extant examples of such indicator systems that I've seen, such as in WW2 training materials for message center staff. Knowledge of the indicator system(s) in use by a particular adversary can help a cryptographer determine the best approach for a particular intercepted message, such as "assume this message is a Playfair cipher from some low-level guy we don't really care about", "send this one straight to the folks breaking Enigma traffic", or "put this one in the don't-bother-trying box".

You can discount gibberish and orders for lamb chops if you are quite confident that the message was, for example, English text, and that "lamb chops" was not a code phrase for something like "crates of ammunition". But you still can't distinguish between "FOURTEENTH TANK BRIGADE WILL ATTACK ON NOVEMBER TWELFTH" vs. "EIGTH INFANTRY BRIGADE RETREATING WITH HEAVY CASUALTIES". In any case, code words, code phrases, abbreviations, jargon and spelling errors can all be reasonably expected in legitimate military and espionage communications, so without detailed inside information, you can't even discount a possible decoding like "RABBITS ARE RUNNING DUE TO CRITICAL LAMB CHOP SHORTAGES". For any given message length, it is quite possible to come up with possible decodings of the same length with exactly contradictory meanings. Thus, even in real life, an intercepted OTP message only gives you an opportunity for traffic analysis.

When properly implemented, one-time pad messages are truly unbreakable in the lab and in practice. Successful cryptanalysis of them is only possible when serious mistakes are made, such as using a single key more than once, using a key that can be predicted by some means, etc.

As an aside, Between Silk and Cyanide was an interesting account of one person's involvement in WW2 cryptography related to espionage operations. If we can assume the author's account is accurate, then there was a lot of WW2 espionage activity using ciphers other than OTP, and OTP (in particular, OTP using letters rather than numbers) was a later development in the war, still further delayed by the complications of distributing key material. So, it makes sense to me for cryptologists to have made an attempt at breaking this recovered cryptogram based on the possibility that some system other than OTP was used to encipher it.

Incidentally, five-letter groups of seemingly-random characters is a common form for enciphered text, and is not specific to OTP. It's conventional to break enciphered text into five-letter groups to make it easier to avoid losing one's place when transmitting it by telegraph or teletype. Cipher machines such as my US WW2 M-209B or my Soviet cold-war Fialka even automatically space the ciphertext out into five-letter groups. It takes actual analysis of a ciphertext to determine what system(s) may have been used to create it. For practical purposes, there will often be information called "indicators" embedded in the ciphertext, so that a busy cipher clerk will know which machine to use and which key to load into it to process that message. There are extant examples of such indicator systems that I've seen, such as in WW2 training materials for message center staff. Knowledge of the indicator system(s) in use by a particular adversary can help a cryptographer determine the best approach for a particular intercepted message, such as "assume this message is a Playfair cipher from some low-level guy we don't really care about", "send this one straight to the folks breaking Enigma traffic", or "put this one in the don't-bother-trying box".

I would think that if you wanted to live out where there were no people, why would you want to be online with them.

Now, that's just silly. We're not just talking about hermits on mountaintops getting their phone lines cut off. My 5-acre property (which was formerly a grapefruit grove, is in an area of citrus groves that are gradually being replaced by residences as the cost of irrigation makes the production unprofitable, and is still zoned as agricultural land) is only 2-3 miles down the road from the nearest tract home neighborhood, is within a short walk from another residential neighborhood of semi-custom homes, and overlooks suburban/urban sprawl that goes all the way to the visible horizon. Yet it's still outside the cable TV coverage area, and its telephone service is provided by a switch which is too far away to provide DSL or even ISDN. There are an awful lot of people who live in areas where analog telephone lines are the only available option for voice or data communications, yet are even less isolated and less rural than my area (which is itself just outside the fringes of city as far as the eye can see).

I moved out here and built a house because I like to have a bit more space around my home than I had when I lived in suburbia, I don't like my neighbors' kids trampling my front yard every day, I don't like hearing my neighbors fighting with their spouses all the time, I like to give my dogs a big yard to run around in, I don't want a homeowner's association telling me what I can and can't do, and I happen to have hobbies which take up a bit more room than a suburban lot can provide (I collect and restore vintage military trucks, and play with ham radio; see my web page if you're curious). But I'm not cut off from humanity, and as an electrical engineer who regularly telecommutes rather than driving to work, I use my (crappy, cellular) data connection quite heavily. And for that matter, I'm online here talking with you right now. ;-)

Now, I'm not saying that the phone companies should be forced and/or subsidized to build out their ISDN/DSL/fiber/etc. infrastructure to serve people like me who chose to give up some public utility access in exchange for a bit more space around their homes, but please understand that a lot more people than just a few isolated hermits would be negatively impacted by pulling the plug on POTS.

Suits like that actually exist. I bought one at a military surplus store. The Navy used them to protect sailors who have to work close to shipboard radar systems. Naturally, they need to completely surround the body to work, so these one-piece suits have booties, gloves, and completely cover the head and face.

US Navy Microwave Protective Clothing

Disclaimer: These WiFi-allergic people are idiots.

The HMMWVs that I'm familiar with (up through at least the early 1990s) have entirely mechanical fuel injection systems. There's a solenoid for fuel shutoff and another for cold advance, but all of the timing and fuel metering is mechanical. I have a 1986 USMC surplus HMMWV, and I'm a lot more familiar with that fuel injection system than I'd like to be since my injection pump was shot when I got the truck!

There's a control box under the dash, but it's pretty low-tech stuff. Big relays and so forth. No CPU.

Now, in the later models that have the 4-speed, electronically controlled 4L80E transmission, as opposed to the mechanically controlled 3-speed Hydramatic 400 in the older trucks like mine, there's a control box for the transmission. I don't know whether it would be susceptible to a microwave doohickey like this one.

I used to have an old M561 Gama Goat. It had a Detroit Diesel 3-53 engine. It was fully mechanically controlled, and even the fuel shutoff was mechanical. I don't think it even had glow plugs. Other then running the starter motor, the electrical system was completely unnecessary to keep the vehicle running and moving. Ah, the good old days! :-)

The HMMWVs that I'm familiar with (up through at least the early 1990s) have entirely mechanical fuel injection systems. There's a solenoid for fuel shutoff and another for cold advance, but all of the timing and fuel metering is mechanical. I have a 1986 USMC surplus HMMWV, and I'm a lot more familiar with that fuel injection system than I'd like to be since my injection pump was shot when I got the truck!

There's a control box under the dash, but it's pretty low-tech stuff. Big relays and so forth. No CPU.

Now, in the later models that have the 4-speed, electronically controlled 4L80E transmission, as opposed to the mechanically controlled 3-speed Hydramatic 400 in the older trucks like mine, there's a control box for the transmission. I don't know whether it would be susceptible to a microwave doohickey like this one.

I used to have an old M561 Gama Goat. It had a Detroit Diesel 3-53 engine. It was fully mechanically controlled, and even the fuel shutoff was mechanical. I don't think it even had glow plugs. Other then running the starter motor, the electrical system was completely unnecessary to keep the vehicle running and moving. Ah, the good old days! :-)

Truck tires often use inner tubes to hold the air, so the 2 or more pieces of the wheel don't need to go together with an airtight seal. The split rims on the larger trucks that you might see on my web site are like this. I couldn't find any pictures online that are as good as the diagrams in my tech manuals, but this page might give you an idea of how these wheels work:

Split-Rim Tyre Repairs

On the bolt-together HMMWV wheels (which use tubeless tires, and have either magnesium or rubber run-flat assemblies installed inside the tires) there's a big O ring seal that goes between the two wheel halves, and the wheels are designed to that the studs which hold the wheel halves together aren't in a pressurized area. Here's a page with some diagrams that show what's going on in one of the varieties of split rims that are used on the HMMWV:

Changing Tires on Hummer Wheels

There are probably other kinds of split-rim wheels, but these are the only two kinds I have experience with.

I should probably say something about the thread topic: My guess is that the guy who made the death-bed confession has a twisted sense of humor and is laughing his etherial ass off if there's an afterlife to do it from.