[GreenKeys] Two-tape TTY for crypto

Tue Oct 13 11:14:17 EDT 2020

Ralph,

Thanks for your details on the use of the PYTHON One-time-tape system!

When was it that you were using that system?

Thanks,

Duncan
K2OEQ

On 13-Oct-20 09:33, Ralph Irish wrote:
> Dave
>
> The others covered most of the topic for the PYTHON system.
>
> I used one for about 18 months while I was in the Navy.  It consisted 
> of two
> Model 14 TDs, one of which basically had no controls other than a 
> 'tight tape
> switch.  It was 'pulsed' by the main system when the device was in either
> ENCRYPT or DECRYPT, with something or someone making the 'ordinary'
> TD operate.  It was interchangeable with the other 14 TDs in the radio 
> room.
>
> This special TD had a much different serializing plate under the 
> cover.  The
> regular TDs had a single copper 'ring' interrupted in several places 
> to represent
> the various parts of an RTTY character.  The special TD had this 
> second ring
> to do the 'logic math' to combine the various 'bits' of a character to 
> form the
> 'processed' character bit, etc.
>
> This second ring did not 'do the math', but was part of the system 
> that did.
> The center ring was 'common', and I think that the outer ring was the 
> 'normal'
> one similar or identical to the other TD.  The center ring was 
> involved in the
> code/decode function somehow.
>
> -   -   -   -
>
> There was a five character 'key indicator' that we watched for.  We 
> had only one
> of them in the crypto area.  These were spooled on red plastic reels, 
> quite similar
> to 16mm film reels, about 6 or 7 inches in diameter.  There was a 
> 'spindle' that
> held the spool to feed this tape into the 'irregular' TD.  Each 
> segment was probably
> 1000 characters long and there was a 'master number' for the large 
> spools, and each
> one had a number every so many characters with a black line across the 
> tape at
> position "Ø"  This was the start point for decoding things.
>
> The incoming tape had a 'header' with some address info, a Date Time Group
> and date, and somewhere after that were two blank characters.  The 
> next character
> was position "Ø" for that.  Once both tapes were in place the "GO" 
> button (forgot
> the real name of it!) could be pushed and the two TDs would start 
> moving and as
> has been said several times there was some internal relay logic that 
> took the 'bits'
> and combined them to decide whether that particular location was a 
> Mark or a SPACE
> or a 1 or a Ø, etc.
>
> As long as the 'random tape' was indeed random, the text would be 
> quite safe.  In
> the late 50s and into the early 60s, there were not too many computers 
> fast enough to
> determine the 'randomness' of a code tape, so things were considered 
> safe enough for
> Top Secret items.
>
> On the few occasions we discovered that a message being decoded was 
> Top Secret,
> the system was stopped and anyone not cleared for T/S had to leave the 
> area.  If no
> one was so cleared, a Comm Officer was summoned to complete the 
> decoding.  Much
> the same for the KL-47 system in another room.  I was also cleared for 
> that equipment,
> but when we were on a WesPac cruise, I had few duties that required me 
> to enter that
> space.  In the states, I stood watches in the Main Communications room 
> and when a
> message came in for that system, I would go into the Crypto Center and 
> decode it.
> Again, if the opening phrase was "Top Secret", the system was stopped 
> and someone
> with the proper clearance would be summoned.
>
> -   -   -   -
>
> The transition that occurred to make the classification the first 
> word/words happened
> when I was still in the Navy.  Evidently, someone, somewhere sent out 
> a classified
> document 'in the clear' which caused 'heartburn' all over the world! 
>  So a decision was
> made to prevent this from happening again.  The word went out that for 
> any message
> going out on Fleet Broadcasts, the first word of it had to be the 
> classification:
>
> //UNCLASS//     //CONFIDENTIAL//    //SECRET// //TOP SECRET//    If there
> were more classifications, I never heard about them.  Probably just as 
> well!
>
> Then there were the 'priorities' of Fleet Broadcast traffic:
>
> Deferred
> Routine
> Priority
> Operational Immediate
> Emergency
> FLASH
> (I think I have these in the right order)
>
> -   -   -   -
>
> It was a most interesting time of my life.  those two-plus years in 
> Navy communications.
> covering voice, Morse, Teleprinter for the in and out things, and then 
> the various types of encoding/decoding were just 'icing on the cake'!
>
> Hope my descriptions are not too complicated.  That is the way I seem 
> to remember
> things from back then.
>
> 73,
>
> Ralph - W8ROI
>
> -   -   -   -   -   -   -   -
>
> *From: *"Dave Horsfall" <dave at horsfall.org>
> *To: *"Greenkeys" <greenkeys at mailman.qth.net>
> *Sent: *Monday, October 12, 2020 3:05:41 PM
> *Subject: *[GreenKeys] Two-tape TTY for crypto
>
> I've been reading a bit of crypto stuff lately (one of my hobbies), and
> something caught my eye; apparently Teletype made a box that took two
> tapes: one was the plain/cipher text, and the other was the key, and the
> two were combined with no-carry addition on the individual bits.
>
> Anyone know any more about this?
>
> -- Dave VK2KFU
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