Codebreaking - Taking the First Step?

Master Spy asks: "Here's something that the Slashdot community might be able to help with. If you receive a message in code how do you take the first step? Back in the days of WWII it was easier. The codebreakers at Bletchley Park already knew that the messages were encoded using an Enigma machine so all they had to do was work out the positions of the rotors using brain power, the Bombe or later the Colossus machine. American codebreakers also knew the basic details about the methods the Japanese used but now however things are more complicated. Suppose you are listening to a transmission and you receive the following: 'sdjek dYqkP 1Nt$% GGl9) MHrYD +++' How do you know how the message has been encrypted? It could be an Enigma machine, it could have been XOR'd with a second message or a one-time pad or it could use some form of software encryption such as Blowfish or DES. Before you start ripping the message apart for decoding how do codebreakers find out what method has been used to encode the message?"

Comments

I've seen that.

[orthogonal]

Suppose you are listening to a transmission and you receive the following: 'sdjek dYqkP 1Nt$% GGl9) MHrYD +++'

Yeah, 'sdjek dYqkP 1Nt$% GGl9) MHrYD +++' showed up on my SETI@home screen too.

This is clearly the signature of the Grays from Cygnus Prime. You don't want to communicate with them.

They Grays of Cynus Prime are evil. They will put chips in your head.

They will use the chips to make you do bad things. Like posting to Slashdot.

Re:I've seen that.

[YetAnotherLogin]

Well, that explains all the goatse ASCII pr0n trolls around here.

encryption breaking

[Dot.Sig]

"Suppose you are listening to a transmission and you receive the following: 'sdjek dYqkP 1Nt$% GGl9) MHrYD +++'"

I transmit a polite reply saying, "No, I am NOT interested in being your love monkey no matter how much you lust after me." Gee whiz! The things people say when they think nobody is listening!

Simple

[splattertrousers]

Suppose you are listening to a transmission and you receive the following: 'sdjek dYqkP 1Nt$% GGl9) MHrYD +++' How do you know how the message has been encrypted?

First you djc,s dk%33R +++ (110), then you sD##N KDL:: Ds03k -332+. From there, it's a trivial matter of just 3!Wop mclDI a002g a!22# with the sklj3 V3iia aq@@1 +1867 -5309.

Duh.

You already know what I'm going to tell you

[GuyMannDude]

If you receive a message in code how do you take the first step?

You do what everyone else here does when they come across a problem that may or may not full under the category "News for Nerds. Stuff that Matters": you submit it to Ask Slashdot, of course! Don't worry: they'll print it. They'll print anything and it doesn't even have to be in the form of a question!

GMD

Social engineering solution

[mbstone]

You social-engineer the NSA or other TLA with teraflop codebreaking computer-capability into helping you crack the message. For example, consider the following method used by an Idahoan to get his potato field plowed:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>& gt ;
An old man lived alone in southern Idaho. It was early spring, and he wanted to spade a garden plot to prepare it for planting potatoes. But it was very hard work and he just didn't have the energy.

You see, his only son, who would have helped him, was in prison.

The old man wrote a letter to his son and mentioned his predicament.

A week later, he received a note back, which said, "For heaven's sake, Dad, whatever you do, don't dig up that section of the garden! That's where I buried the GUNS!"

The next morning, bright and early, a dozen police showed up and dug up the entire garden, without finding any guns.

Looking out the kitchen window, the old man thought "Now, what in the world is going on here?" Confused, he wrote another letter to his son telling him what happened, and asked him for advice.

Another week passed and his son's reply arrived in the mailbox. The old man carried the letter up to the house, sat down at the kitchen table and read, "Now plant your potatoes, Dad. It's the best I could do for you under the circumstances."

echo /dev/urandom /dev/ttyS0

[Emrikol]

sdjek dYqkP 1Nt$% GGl9) MHrYD +++

NO CARRIER

Damn line noise...

Good old memories!

Re:know your tools

[Anonymous Coward]

I agree totally.

I've been working years on this message sent to me in 1983.

Please help if you can.

Here is the message with quotes:

'T'

Thanks

Hrmph..

[penguin_punk]

Thanks Cliff, now everyone knows Osama's slashdot nick.

sdjek dYqkP 1Nt$% GGl9) MHrYD +++

[pizza_milkshake]

sdjek dYqkP 1Nt$% GGl9) MHrYD +++

this is obviously perl code

Code broken!

[Telecommando]

'sdjek dYqkP 1Nt$% GGl9) MHrYD +++' decrypts to,

'I send you this file in order to have your advice'

Are you so sure?

[Scorchio]

Now, Pinky, with this new encryption scheme that deliberately resembles random typing, we shall take over the world!