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Minutes of SCAG Sessions 

June 4 and 5, 19 51 

The sessions proceding according to the agenda, with the following changes 

and elaborations. 

June 4, 13001 

Following LCDR Gleason's talk there was discussion on German success on 

our traffic, the enciphering of intercept, and the volume of traffic. There 

were also some questions about one-time additives, irregul.8.r stepping, and 

other complications for achieving security. 

The following tour visited GOLDBERG, DEMON, a EOMBE, and ATLAS. 

Then there was a. session outlining AFSA1 s computer program: ATLAS I, 

ABlmR, ATLAS II, and NOMAD. 

June 5, 0900: 

Mr. Ba.ven gave an e:a:position of where A!JiATROSS fitted into Russian 

communications, and what bad alread¥ been recovered concerning it. Some 

questions elicited further details. 

Mr. Shepard then gave a.n abreviated account of the round robin search 

for depths on ALBATROSS. 

Mr. Levenson described the important slow wheel isomorphs. 

Mr. Marston elaborated on this with a worked out example. 

After lunch SCAG reassembled in Dr. Highley•s office, where a description of the logical design of SKA.TE was ma.de. Then a tour of .AFSA-22, 

examining principally the big and unusual equipments, SKATE, 01MALLEY, and 

the Chinese typewriter. 

From here they went to see ROBIN and CONN;E in building B, and then 

Al3NER. 

June 5, 1445: 

In room B2010, P..r. Ba.ven spoke on isomorphism. Then Mr. Levenson 

brought up some general questions regarding wired wheels which have not 7et 

T9P SECRH 

Declassified and approved for release by NSA on 04-02-2014 pursuantto E.O. 1352a 
REF ID:_A~605. 

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Minutes of SOAG Sessions, June 4 and 5, 1951 

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been answered. They were, paraphrased, 

1) How many distinct wheels are there with a given number of parallel 

pairs of wiresT 

2) How can cryptanalytic use be ma.de of tbe fact that the number of 

parallelisms is restrictedT 

3) Can we recognise the re-use of a slow wheel in isomorphs f'rom 

chains of the rod-squareT 

4) How many whee~s are reconstructable from a given amount of data? 

After some discussion of how people would make u;p wheels "at random", 

the group split into two at 1530. 

Mr. Roberts ma.de a presentation of SWEATER, which was cut short at 1615 

without discussion. 

Mr. Howard said that there were really two groups here, one of ma.the,:) 

ma.ticians and an.other of engineers, and that tbe two should be treated .. ( 

differently. Mr. Potter added that there also seemed to be two distinct:J 

problems, theory and practice. Dr. Tompkins objected that separately the . engineers and mathematicians could not arrive at feasible solutions, but · that together t~y might. •' 

In the Headquarters building the Admiral asked each SCAG member for 

an impression. There was discussion of the feasibility of declassifying 

problems for outside study. The members agreed that they needed and wanted 

to know more. There was discussion about how SCAG should or could operate. 

Admiral Stone designated Capt. Harper as the official contact with SO.A.G members, 

and set the next full meeting to be on July 10 at 1000, to continue for the 

rest of that week. 

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