ANN: obfuscate

[Paul Rubin]

Actually I gather it had a lot to do with the fact that the Germans
made some blunders in the way they used the Enigma that seriously
compromised its security. There was reportedly a branch of the German
forces that used their Enigmas differently, avoiding those mistakes,
and the British never managed to crack any of their messages.

I think you are thinking of the Kriegsmarine (naval) Enigma. Yes they
were more careful with procedures, but the machine was also harder to
crack because it had four rotors instead of three. IIRC, the Brits were
eventually (1942?) able to capture one by shooting up a German submarine
and boarding it to get the machine while the sub was sinking; a British
sailor wasn't able to get out in time and drowned during that operation.
Getting the rotor settings off the captured unit (they may have had to
do it more than once) was enough to get a foothold into the code. My
memory is hazy on this by now so I may have some parts wrong, but David
Kahn's book "Seizing the Enigma" tells the story (I read it many years
ago). A fictionalized version appears in Neil Stephenson's novel
"Cryptonomicon".

 

[Tim Golden]

I think you are thinking of the Kriegsmarine (naval) Enigma. Yes they
were more careful with procedures, but the machine was also harder to
crack because it had four rotors instead of three. IIRC, the Brits were
eventually (1942?) able to capture one by shooting up a German submarine
and boarding it to get the machine while the sub was sinking; a British
sailor wasn't able to get out in time and drowned during that operation.
Getting the rotor settings off the captured unit (they may have had to
do it more than once) was enough to get a foothold into the code. My
memory is hazy on this by now so I may have some parts wrong, but David
Kahn's book "Seizing the Enigma" tells the story (I read it many years
ago). A fictionalized version appears in Neil Stephenson's novel
"Cryptonomicon".

And for those who haven't been to Bletchley Park [*] I recommend it.
Not only is it full of interesting stuff, but it has an engagingly
amateurish air about it which I personally prefer to the sleek-and-shiny
nature of many museum-y places today. When I was there last summer I
was disappointed to see that they'd closed the Pigeon Museum. But the
Model Railway club was still there (altho' we were too late in the day
to get in) and the new Computing Museum is full of delightful nostalgic
clutter being worked on by enthusiastic people. My kind of place..

TJG

[*] http://www.bletchleypark.org.uk/

 

[MRAB]

IIRC some versions of the Enigma weren't cracked because they used a
different setup and different daily keys.

The predecessor of the Enigma was cracked by Polish scientists years
before WW2 started. Some flaws in the instructions and a known plain
text attack made the crack of the Enigma practical. It took the
British scientists merely hours rather than days or weeks to decipher
the daily key with some smart tricks. For example they started fake
attacks on ships or cities just to have the names in some encrypted
reports.
>

In some cases the British had decoded the messages before the intended
recipient!

The Americans decoded Japanese messages about an planned attack on an
island, but didn't know which one because of the fake names, so they
instructed their bases to report certain problems in a way that the
Japanese could decode.

Midway reported a shortage of water, the Japanese decoded it and sent a
message about it, the Americans decoded their message and discovered
that island's fake name, and thus found out that Midway was the intended
target of the attack.

 

[Matthew Barnett]

I think you are thinking of the Kriegsmarine (naval) Enigma. Yes they
were more careful with procedures, but the machine was also harder to
crack because it had four rotors instead of three. IIRC, the Brits were
eventually (1942?) able to capture one by shooting up a German submarine
and boarding it to get the machine while the sub was sinking; a British
sailor wasn't able to get out in time and drowned during that operation.
Getting the rotor settings off the captured unit (they may have had to
do it more than once) was enough to get a foothold into the code. My
memory is hazy on this by now so I may have some parts wrong, but David
Kahn's book "Seizing the Enigma" tells the story (I read it many years
ago). A fictionalized version appears in Neil Stephenson's novel
"Cryptonomicon".

U-559? I think that's the one where Hollywood made a film about it, but
portraying it as a purely American action. That didn't go down too well
in the UK!

 

[MRAB]

I think you are thinking of the Kriegsmarine (naval) Enigma. Yes they
were more careful with procedures, but the machine was also harder to
crack because it had four rotors instead of three. IIRC, the Brits were
eventually (1942?) able to capture one by shooting up a German submarine
and boarding it to get the machine while the sub was sinking; a British
sailor wasn't able to get out in time and drowned during that operation.
Getting the rotor settings off the captured unit (they may have had to
do it more than once) was enough to get a foothold into the code. My
memory is hazy on this by now so I may have some parts wrong, but David
Kahn's book "Seizing the Enigma" tells the story (I read it many years
ago). A fictionalized version appears in Neil Stephenson's novel
"Cryptonomicon".

U-559? I think that's the one where Hollywood made a film about it, but
portraying it as a purely American action. That didn't go down too well
in the UK!

 

[Mark Lawrence]

IIRC some versions of the Enigma weren't cracked because they used a
different setup and different daily keys.

The predecessor of the Enigma was cracked by Polish scientists years
before WW2 started. Some flaws in the instructions and a known plain
text attack made the crack of the Enigma practical. It took the British
scientists merely hours rather than days or weeks to decipher the daily
key with some smart tricks. For example they started fake attacks on
ships or cities just to have the names in some encrypted reports.

I believe that all of Enigma was eventually cracked cos of two major flaws.
1) A letter could never be sent as itself.
2) The Luftwaffe were very poor when compared to the Wehrmacht or
Kriegsmarine about security so they were a major leak of data regarding
the other organisations.
3) The users instead of using random three letter combinations kept
using the same ones. HIT LER and BER LIN were popular, but the most
famous one at Bletchley Park was the name of the guy's girlfriend.

Further, the far more powerful Geheimscreiber was also cracked at
Bletchley by using Colossus. Sorry some years since I read the book
about this so can't remember the title or author.

Regards.

Mark Lawrence.

 

[Paul Rubin]

I believe that all of Enigma was eventually cracked cos of two major
flaws.

I think it never would have been cracked if it hadn't been cracked
(whether by the Brits or the Poles) before the war started, using
commercial versions of the Enigma that they had access to. The military
Enigma and its operating methods got more sophisticated as the war went
on, and the cryptanalysts were able to keep up with it by incrementally
improving techniques that they were already using at scale. If they
were suddenly confronted with the full-blown military system in the
middle of the war, it would have been a lot harder to do anything about
it. At least, most of the Enigma-related books I've read give that
impression and even come out and say such things.

Further, the far more powerful Geheimscreiber was also cracked at
Bletchley by using Colossus. Sorry some years since I read the book
about this so can't remember the title or author.

See http://en.wikipedia.org/wiki/Colossus_computer
That was almost at the end of the war though.

 

[Bob Martin]

See http://en.wikipedia.org/wiki/Colossus_computer
That was almost at the end of the war though.

Colossus was working by the end of 1943 - the year that the Americans first dropped
bombs on Germany ;-)

 

[Jean-Michel Pichavant]

Colossus was working by the end of 1943 - the year that the Americans first dropped
bombs on Germany ;-)

sept 1939 - sept 1945. It's nearer from the end, than from the begining.

JM

 

[Bob Martin]

sept 1939 - sept 1945. It's nearer from the end, than from the begining.

If I must spell it out ;-)
Near the end for us Brits but the Americans were only just getting into the action
in Europe.

 

[Mark Lawrence]

I think it never would have been cracked if it hadn't been cracked
(whether by the Brits or the Poles) before the war started, using
commercial versions of the Enigma that they had access to. The military
Enigma and its operating methods got more sophisticated as the war went
on, and the cryptanalysts were able to keep up with it by incrementally
improving techniques that they were already using at scale. If they
were suddenly confronted with the full-blown military system in the
middle of the war, it would have been a lot harder to do anything about
it. At least, most of the Enigma-related books I've read give that
impression and even come out and say such things. I completely agree.


See http://en.wikipedia.org/wiki/Colossus_computer
That was almost at the end of the war though.