Download e-book for kindle: Cryptography: The Science of Secret Writing by Laurence D. Smith

By Laurence D. Smith

ISBN-10: 048620247X

ISBN-13: 9780486202471

"Those who enjoy puzzles can locate a lot to examine here." — Science information Letter
"Will be good acquired through somebody particularly attracted to the subject." — Scientific publication membership Review
Readers drawn to mystery writing will locate this booklet a good straight forward clarification of transposition and substitution ciphers, codes, and their recommendations. greater than a hundred and fifty difficulties supply useful software in addition to exams of ability and ingenuity.
After a short description of the background of mystery writing, the reader is brought to primary rules of ciphers — transposition and substitution — and given an knowing of a number of the equipment of enciphering and decoding mystery messages. the writer covers geometrical styles, course transcription, columnar transposition, and different equipment utilized in transposition; below substitution, he treats combined cipher structures, single-alphabet and polyalphabetical substitution, mechanical units, the Vigenère approach, and so on. A dialogue of cryptanalysis leads the reader into 151 difficulties for which solutions are supplied on the finish. Appendixes provide notes on enciphering jap; and clarification of the Baconian Biliteral Cipher; frequency tables for English, French, German, Italian, and Spanish.

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Extra info for Cryptography: The Science of Secret Writing

Example text

X ( y and z are omitted). Since it is possible for each route to have a different starting point, variations 1, 2, 3, et cetera, show the same route started from the different comers of the rectangle. ORTHOGONAL ROUTES A. 1 ABCDEF GH I J K L MNO PQR S TUVWX Simple Horizontal 2 3 4 FEDCBA LKJIHG RQ PONM XW V U T S S TUVWX MNO PQR GHI J K L ABCDEF XWVUT S RQ PONM LKJIHG FEDCBA B. Simple Vertical 1 2 3 4 AEI MQU B FJ N R V CGKOSW DH L P T X U QM I E A V RNJ FB WSOKGC XTPLHD DH L P T X CGKOSW B F J NRV AEIMQU XTPLHD WSOKGC V R NJ FB UQMI E A 42 CRYPTOGRAPHY C.

One may use playing cards; pictures; dots and dashes; arms, flags, or lanterns, as in semaphoring; or any variety of symbols or hieroglyphs. But in practice there are serious limitations. For instance, in devising the ex­ ample of symbol substitution given below, we are placed under compulsion, by the facilities of our printer, to use only symbols that appear in his type book. Thus with the printer’s con­ venience in mind we can prepare alphabetical equivalents: A B C D E F G H I u J A ( K L M N l ; + 1 s?

2 . The starting place and the route by which the message will be inscribed. 3. The starting place and direction for tran­ scription. 4. The group lengths for the final cipher text. ) TRANSPOSITION CIPHERS 45 We decide on the four points as follows: 1 . T o use a completely filled rectangle of six columns and four rows. 2. T o inscribe the letters of the plain text within this rectangle by taking the route of B -l, s h o w on page 41, starting in the top left - hand comer. 3 . T o transcribe the thus inscribed letters by following route G -4 to form the cipher text.

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Cryptography: The Science of Secret Writing by Laurence D. Smith

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