# The Newmanry History

## Part of the General Report on Tunny(1945)

### Page 365

Tony Sale's
Codes and Ciphers

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55C Page 365

(iii) V The depth is on a tape fed into a tape-reader.

(c) Operation

Proteus is started: it reads and remembers the first seven letters of the
depth, adds them to the crib, and as the dictionary is scanned adds this also in
all positions looking for a click consisting entirely of strokes.

If no click is found, the tape reader steps. Proteus acquires the 8th
letter and forgets the 1st, so that letters 1-7 are replaced by letters 2 - 8; and
so on.

When a click is found, Proteus stops, and displays

(i) The position in the depth (last letter) measured in lines 31 long.

(ii) The successful crib (1,2,3,4,5, or 6).

The place in the dictionary must be found by hand,(by addition).

The anagram can be checked throwing a switch to "rerun", so re-examining the
same seven letters of the depth.

To resume stepping throw the switch to "reset".

(d) Other Applications

Proteus is equally applicable to any mod-2-addition teleprinter cipher
which has true depths.

55C AQUARIUS Fig 58(xxxii).

(a) Purpose and method

Aquarius sets go-backs [28B(f)] using a de-chi.

In the correct position, the two P's are the same, so that Delta-D(a) +
Delta-D(b) = Delta-P(a) + Delta-PSI'(a) + Delta-P(b) + Delta-PSI'(b) = Delta-
PSI'(a) + Delta-PSI'(a)

Aquarius adds a stretch of de-chi immediately after the autopause to a
stretch before the autopause, differences the sum, and makes counts for
resemblance to the sum of two Delta-PSI's. The proportional frequency of each
letter depends only on the number of crosses in it. and the six switches are for
counting letters with 0,1,2,3,4,5 crosses: throwing more than one switch
provides "either - or",

Two counters are provided (generally used for all dots, all crosses.)

(b) Stepping

At first the comparison is made on a steadily increasing, text, thus: first
11 letters after the auto-pause with last 11 before; then first 12 after with last
12 before, and so on.

After the text length has reached 97 there is no further increase, but the
97 letters following the autopause are stepped back relative to the part before
the autopause. 97 letters are sufficient: in a long go-back the letters
immediately before the autopause may be rubbish.

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