Improvements in or appertaining to Writing or Deciphering Crypto- graphic Correspondence on Type-writers. APPER TAI TO WRITING OR DECIPHERINGYPTOGRAPHIC
Year: 1891

page_text: Date of Application. 7th Jan., 1891-Accepted, 21st Feb., 18:1
COMPLETE SPECIFICATION.
Improvements in or appertaining to Writing or Deciphering Crypto-
graphic Correspondence on Type-writers.
I, EDWARD DE LANOY LITTLE, of The Mount, Northallerton, Master of Arts,
do hereby declare the nature of my invention for IMPROVEMENTS IN OR APPER-
TAINING TO WRITING OR DECIPHERING CRYPTOGRAPHIC CORRESPONDENCE ON
TYPE-WRITERS, and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to apparatus to be attached to suitable type-writers, by
means of which telegraphic and other communications can be both written and read
in pure letter cipher, and which affords a practically unlimited variety of code
without altering in any way the construction of the type-writer, or the arrangement
of its alphabet or scale of characters, and renders type-writers of different alphabets
available for such correspondence.
Any keyed type-writer, that is to say, any type-writer with which a character is
written by pressing down a key inscribed with that character, is suitable to the
invention.
The apparatus consists of a frame to be superimposed upon the key-board, or any
selected part of the key-board, of the type-writer, in such a way that a small tube
stands directly above each key of the type-writer to be called into use. Into these
tubes are inserted keys, easily removable and transferable, and inscribed with the
same characters as the keys of the type-writer, but not necessarily in the same
position or order as those keys.. When one of these cipher-keys is pressed
down, it carries with it the key of the type-writer over which, and in contact with
which, it stands, and causes it to print the character with which the key of the
type-writer is inscribed, so that while the operator appears to write any given
character, he actually writes a different character. His correspondent arranges
the cipher keys of similar apparatus in the requisite order and position, and while
appearing to write any given character occurring in the cipher communication
actually writes the original character of which it forms the cipher.
The invention is available for various kinds of cipher, which may be classified
as follows:-
Firstly. The two type-writers employed may have the same alphabet; in which
case three different kinds of cipher are available.
1. The alphabet of both type-writers read backwards may be used as the
cipher-alphabet both in ciphering and in deciphering. For example, if the
alphabet of the type-writers, abridged for the sake of illustration, were
ABCDEF the cipher alphabet employed by each correspondent might
be D C B A FE.
In this case the same adjustment of the cipher-alphabet to the alphabet of the
type-writer, or the same key, would serve both for ciphering and for
deciphering; and there would be twenty-six such adjustments or keys
possible.
2. The alphabet of the type-writers read forwards may be used as the cipher-
alphabet of each.
In this case, in deciphering the cipher-alphabet must be moved as many places
in one direction, as regards the alphabet of the type-writer, as it was
previously moved in the other direction in ciphering. The number of
adjustments of the cipher-alphabet to the alphabet of the type-writer, or the
number of possible keys will be twenty-six.
3. The cipher-alphabet used in ciphering may be in any order whatever. In
this case the cipher alphabet used in deciphering will differ both from the
Price Ad

page_text: alphabet of the type-writers and the cipher alphabet used in ciphering. For
example, if the alphabet of the type-writers were A B C D E F, and the
cipher alphabet used in ciphering were C A FE B D, since in ciphering A
would be the cipher of C, in deciphering C would be the cipher of A, and
therefore A would be the third in order of the cipher-alphabet, and so with
other letters. Hence the cipher alphabet used in deciphering would be
BEAFDC. In this kind of cipher for every fresh adjustment of any
particular cipher alphabet to the alphabet of one of the type-writers, a fresh
cipher-alphabet must be used with the other.
Secondly. The two type-writers employed may have different alphabets; in
hich case two different kinds of cipher are available.
1. The cipher alphabet used with each type writer may be the alphabet of the
other. For example, if the alphabets of two type-writers were ABCDEF,
and C F A DE B respectively, and if FA DE BC the alphabet of the
second were used as the cipher-alphabet in ciphering with the first, then the
cipher-alphabet used in deciphering with the second would be F ABCDE
which is the alphabet of the first.
In this case there will be twenty six possible adjustments of each cipher
alphabet to the alphabet of the type-writer, or twenty six keys.
2. An alphabet differing from that of each of the type-writers may be used in
ciphering with one, when a fourth alphabet differing from each of the
other three must be used as the cipher alphabet in deciphering with the
other.
This case is similar to the third case of ciphers available where the type-
writers have the same alphabet, and, as in that case, for every fresh adjust-
ment of any particular cipher-alphabet to the alphabet of one of the type-
writers, a fresh cipher-alphabet must be used with the other.
It is evident that in every case considered, the adjustment which serves for
eciphering with one instrument will also serve for ciphering with that instrument,
the adjustment of the corresponding instrument, already used in ciphering, be
reserved in deciphering.
Although the number of keys or possible adjustments of any given cipher-
phabet to the alphabet of a type-writer is limited, the number of codes, that is
say, of possible cipher-alphabets, is practically unlimited.
Having now particularly described and ascertained the nature of my said inven-
on, and in what manner the same is to be performed, I declare that what I
aim is :-
:-
1. In apparatus such as described the attachment of such a frame as is above
escribed to a type-writer, whereby it is rendered available for writing and
eciphering cryptographic communications, and that without alteration of the
onstruction or ordinary use of the type-writer.
2. In apparatus such as described the use of readily moveable keys as cipher
eys, whereby, in the first place, the number of codes or cipher-alphabets available
such apparatus is rendered practically unlimited, and that without altering the
phabet of the type-writer, and in the second place, two type-writers of different
phabets are rendered available for cryptographic correspondence with one
other.
Dated this 6th day of January 1891
E. DE. L. LITTLE.