[Hallicrafters] crypto

[Bob W7AVK]

Group - I believe one of the reasons for the 5 letter group was 
uniformity.  That is everything was the same and you couldn't look for 
spaces, etc when trying to break or get into the code.

Many of the very low level codes used in the field were based on a 5 
letter or number groups.   I don't know the exact reason for the 5 
letter code group or when it got started, but the format goes back well 
before WWII.

73  Bob  W7AVK
USAR Signal Corp Retired

Thomas C. Dailey - Dailey Services, LLC wrote:
> Some of the earlier cypher machines utilized 4-element groups, 
> including some of the Japanese and Polish codes.  All of the 
> relatively comtemporary crypto gear I used in the US Navy, used 
> 5-letter code groups.  The earlier machines were based (not so 
> loosely) on the German Enigma design, and of course, later gear uses 
> electronic shift-registers to select random characters, with changing 
> timing tracks - get a machine's timing, and you have a good chance on 
> decyphering the output.  That's what I FIRMLY believe we fed the 
> Koreans (read Chinese & Russians) from the USS PUEBLO, which enabled 
> US to read THEIR traffic, due to their copying of our designs. Sorry, 
> no more info from me on that subject.
>
> About a year ago, at about 1300Z, on Tuesday, Thursday, and Saturday 
> mornings, I copied 5-letter code groups on 12.093 and 12.235 mHz for a 
> while.  I'm reasonable certain that it was Indian or Pakistani, as 
> once there was some plain text sent, and many of the terms and words 
> were of that genre'.
>
> Look up BLETCHLEY PARK, UK - the home of the ULTRA and ENIGMA 
> code-breaking efforts in WW-II.  An amazing place to visit.
>
> 73 es ZUT AR
>
> Tom Dailey
> former RMC USN
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