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Ciphers for spies in .NET Access code 128 barcode in .NET Ciphers for spies




How to generate, print barcode using .NET, Java sdk library control with example project source code free download:
Ciphers for spies generate, create code128 none on .net projects Microsoft Office Development. Microsoft Office 2000/2003/2007/2010 Book ciphers A spy must avoid arousing suspicion and so any cipher equipment he has in his house must not be obvious. Even a single stencil might appear suspicious to an investigator and a stack of stencils could be incriminating. Likewise a spy would be unlikely to use a code if it meant having to have a large code-book in the house.

A cipher that requires no unusual equipment is therefore a very attractive proposition so far as a spy is concerned and a book cipher is precisely that; all that is required is a book on any topic which does not employ non-Latin alphabetic characters. The book could, for example, be an English novel or a biography or historical work but probably not one dealing with organic chemistry. Using a book cipher In order to use a book cipher it is necessary to be able to add and subtract pairs of letters of the alphabet.

This is done, as explained in 1, by numbering the letters of the alphabet A 0, B 1, C 2,...

, Z 25 and adding or subtracting (mod 26) and re-converting the answers to letters. Since this is a tedious process it is better to make up tables once and for all and look up the result of adding or subtracting in the appropriate table, but to show how to do it without such tables let us carry out the process on a few letters. Example 7.

3 Convert the alphabet to numbers beginning with A 0, B 1 etc. Then add together the two texts below (mod 26) and re-convert the resulting numbers to letters. Text 1 THEXCURFEWXTOLLSX Text 2 ONCEXUPONXAXTIMEX.

Solution We repeat Table 1.1 as Table 7.1. Table 7.1 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 00 01 02 0 3 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25. chapter 7 We rst convert the texts to numbers by using the table: Text 1 Text 2 T H E X C U R F E W X T O L L S X 19 7 4 23 2 20 17 5 4 22 23 19 14 11 11 18 23. O N C E X U P O N X A X T I M E X 14 13 2 4 23 20 15 14 13 23 0 23 19 8 12 4 23. Now we add .net framework Code-128 them and then reduce them (mod 26): 19 7 4 23 2 20 17 5 4 22 23 19 14 11 11 14 13 2 4 23 20 15 14 13 23 0 23 19 8 12 Sum: 33 20 6 27 25 40 32 19 17 45 23 42 33 19 23 (mod 26): 7 20 6 1 25 14 6 19 17 19 23 16 7 19 23 Finally we convert the numbers back into letters, using the table: 18 4 22 22 23 23 46 20. H U G B Z O G T R T X Q H T X W U and this i barcode standards 128 for .NET s the cipher text that would be sent. The recipient would, of course, need to subtract Text 2 from the cipher (mod 26) in order to recover Text 1, viz: Cipher H U G Text 2 O N C Convert 7 20 6 14 13 2.

B Z O G T R T X Q H T X W U E X U P O N X A X T I M E X 1 25 14 6 .NET Code 128C 19 17 19 23 16 7 19 23 22 20 4 23 20 15 14 13 23 0 23 19 8 12 4 23. Subtract ( mod 26), i.e if the result is negative, add 26: 19 7 Re-convert to letters: 4 23 2 20 17 5 4 22 23 19 14 11 11 18 23. T H E X C U R F E W X T O L L S X which is T ext 1, the original message . Obviously it would be a very tedious and error-prone process to have to convert the texts to numbers, add them, subtract 26 where necessary, and re-convert to letters every time a message was to be enciphered so it is very worthwhile having two tables, one for enciphering and one for deciphering, from which the result of applying these processes can be read off immediately. Experienced users would not need such tables since they would soon learn to add the letters at sight but for others the tables save a lot of time and effort.

They are given in Tables 7.2 and 7.3.

Notice that in the encipher table (Table 7.2) it makes no difference whether we call the.
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