IN RE!PLY RE:FER·TO 

REF ID:A52175Be 

WAR DEPARTMENT 

OFFICE OF THE CHIEF SIGNAL OFFICER 

WASHINGTON 

April 8, 1935 

Invention of Cipher Wheel Control Mechanism for a cipher 

machine of the type of Converter M-134-T2 ~ ~ 

~ ~. 

".( 

1. Have five toothed wheels with varying numbers of teeth, all being ~ prime to one another. For example, 37, 38, 39, 41, and 43 teeth. . .L~ ~].,, 

~ ~~ ~ ~.,>_t~ tf...o.. /9Mtft1 ~~IL~~ 2. These whee:I.s are mounted on a comm~ shaft~Jhey are driven 

~~~~~· 

stepwise by meshing gears which mesh with the peripheral teeth for drivi~. ~ 

~tl~~<'.'a_~oQ,,t'..~~~~~~· 

3. Mounted on each wheel is a collar, split into two pieces so as to 

be demountable easily by removable screws. These collar rings have notchings 

in irregular sequences. The notchings on the collars of the different wheels 

are all different and can be varied at will by issue of new collars or new 

1/2 collars. 

4. These notchings control contacts for opening and closing circuits 

to cipher wheels of cryptograph. 

5. Switching arrangements are provided so that the toothed wheels can 

be made to control the cipher wheels permutatively. Example: Toothed wheel 

No. 1 can control cipher wheel No. 3; toothed wheel No. 2 can control cipher 

wheel No. 5, etc. 

6. Paired toothed wheels, ten in all, can be employed as an alternative 

scheme. By appropriate switching arrangements TW1 and TW6, for example, can 

be made jointly to control one contact; TW2 and TW9, anotlier, etc., so that 

the ten toothed wheels control, jointly in pairs, the five contacts which open 

and close the circuits for the cipher wheel stepping magnets. This arrangement would provide for a key of enormous length and variability. 

7. Markings are provided on the periphery of the toothed wheels, for 

purpo.ses of aligning them on a bench mark, so as to set the wheels according 

to a ~ey. 

S. The scheme is not limited to having 5 (or ten paired) toothed wheels. 

One can have as many toothed wheels (or pairs of toothed wheels) as cipher 

wheels in the cryptograph. Example: A cryptograph with 4 cipher wheels would 

have 4 toothed wheels (or 4 pairs if scheme in Par. 6 is used); a cryptograph 

with 6 cipher wheels would have 6 toothed wheels (or 6 pairs), etc. 

William F. Friedman. 

JA'pproved for Release by NSA on 12-16-2013 pursuant to E.O. 1352§ 
·; .. 

WAR DEPARTMENT 

OFFICE OF THE.CHIEF SIGNAL OFFICER 8 

April·~· im 

. . 

WASHINGTON 

. ment1oJl o£ Cipher Wheel Coatrol lechaaiam for a ciph~ 

MCblae ot the Vpe of Colmlrter ll-1J4-T2 

1. BaYe tln toothed wheels with 'f'8J.7iJlg 11abers of teeth, ill beiag 

pr1ae to oae·another. For example, 37,. JS, 39, 41, and 43. teeth. 

2. Tbe·ae Wheels are moated cm a common sbaf't bat ~a . aot ke1ed to 

the. sb&fi, ~bg t~ee to rotat.e..iadepeadentq ., ·.They are driTea s.tepri.se 

by mesh.big ·:gears which mesh with the peripheral teeth for drivillg. The 

driv.lng gears. are mouated upoa and keyed to a comaoa drive shaft.. 

3. Mounted on each wheel is a collar, split 1.Jlto two pieces 30 as 

to be deaotmtable easily by removable screws. These collar rings have 

notchings in irregular sequ.en.ce.s. The notchiDgs on the collars of the 

d1£ferent wheels are all difterent and can be varied at 'ifil1 by issue of 

new collars or new 1/2 collars .. 

4. These a.otcbings control cou't.acts £or opening and closing circuits 

to cipher wheels of cryptograph. 

. 5. $Witching arrangemeirts are provided so that the toothed wheels can 

be ude to control tba cipher wheels permatatively. Examplei Toothed wheel 

No. l can control cipher wheel No. 3; toothed wheel No. 2 Cdn control cipher 

whee1 Bo.·5. etc. 

6. Paired toothed wheels, ten in all, can be emplo7ed as sn alternative 

scheme. By appropriate switch!Dg arrangements ~ and n 6, for exasple, Call 

be made joi.ntly to control onecout&ct1 n 2 and n 9, a.not.her, etc., so that 

the ten toothed wheels control, jointly in pairs, the f'ive contacts wh1eh open 

and el.ose .. the circuits tor the cipher. .whee~. _stepping magnets~ . _This ~-.eaerit · wou<f· Pn;dde for Ii-key of enoriious.1eiatth and var1ab111~. · 

. . : .·. 7~· · akr~s are' Pr~ Oll. tb~ .per1Pltery ~f the "to~thed wheels, for 

parposes or. aligning 'thea Ol:l a bench .mar.t, so as to• set. the wheels'aoOord.hg to a :k97.... · · · . . · · · 

8. The scheme ~ aot j.iiaited to having 5 (0r ten paired) toothed wheels. 

One-can have as.mani'toothed wheels (or pairs of toothed wheels) as· cipher 

wheels 1n the ~ograph. kamplet . A. a,~. ograph with 4 cipher wheel.e.1foald 

ba~e 4 toothed wheels (or 4 pairs if' scheme in Par. 6 is •sed)J·a or,.ptogioaph 

with 6 cipher wheels would baye 6 toothed wheels (or 6 pairs), etc. 

lllllaa 1 ~· Prledmaa. 

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