discussions

Running head: Code breaking

Code breaking

Author’s Name

Professor’s Name

Institutional Affiliation

Date

Question:

Code breaking is the art of accessing information that someone else does not want you to have. This definition sounds simple, doesn't it? Here is one that is a little bit more involved. Code rreferred to as cryptanalysis, which is the body of k unelating to studying cryptosystems, as well as taking encrypt data and decrypting it without a key.a Primary Task Response:

Discuss three basic principles that we can use to break codes or systems. Select one of the puzzles from pages 165 – 168 of our text. Work the puzzle you selected to break the code. Present the solution and the steps you took to break the code.

Steganography

is the hiding of a secret message within an ordinary message and the extraction of it at its destination.It is the oldest form cryptography examples are writing on a slave’s shaved head or on the wood beneath the wax of writing tablets. Generally it takes a step farther by hiding an encrypted message so that no one suspects it exists.  Other examples are writing with lemon juice, microdots, or using the least significant bits in digitally encoded pictures .For example, used by Richelieu. In digital steganography, data is first encrypted and then inserted to unnecessary information using a special algorithm.

Codes

A code is a method used to encrypt a message that operates at the level of meaning; that is, words or phrases are converted into something else.  Codes replaces long words with shorter words, allowing the same information to be sent with fewer characters, more quickly, and less expensively.Coding enables communication in places where ordinary plain language, spoken or written, is difficult or impossible.Tables list every possible plaintext for encryption and every possible cipher text for decryption .Listed items can be letters, sentences, names etc. Items not in the table are sent in clear For example, used by Mary Queen of Scots

The principle of codes includes two processes, encoding and decoding. The process of encoding converts information from a source into symbols while Decoding is the reverse process, converting code symbols back into a form that the recipient understand

Ciphers

Is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. Codes generally substitute different length strings of characters in the output, while ciphers generally substitute the same number of characters as are input. (What we use in modern cryptography) Overlap as a method with code tables, when every possible plaintext is in the table. Use of alphabets, which can consist of just printable characters, bit sequences of any fixed length or anything else defined as a finite set. Plaintext and cipher text do not necessarily use the same alphabet. The cipher text message contains all the information of the plaintext message, but is not in a format readable by a human or computer without the proper mechanism to decrypt it.

A 1

B 2

C 3

D 4

E 5

F 6

G 7

H 8

I 9

J 10

K 11

L 12

M 13

N 14

O 15

P 16

Q 17

R 18

S 19

T 20

U 21

V 22

W 23

X 24

Y 25

Z 26

Use this to map cipher text to plaintext.

So the solutions to Puzzle 8 (i.e. cipher text: 3 1 14. 25 15 21 . 11 5 5 16 . 1 . 19 5 3 18 5 20) would be: [Here '.' stand for space between words]

Plain text: "Can you keep a secret"

And that for Puzzle 9 (i.e. cipher text: 1 12 23 1 25 19. 18 5 1 4 25. 1 12 23 1 25 19. 20 8 5 18 5) would be:

"Always ready always there"

References

 Shannon, Claude (4 October 1949). "Communication Theory of Secrecy Systems". Bell System Technical Journal. 28: 662.

 Kahn, David (1996), The Codebreakers: the story of secret writing (second ed.), Scribners, p. 235

Helen Fouché Gaines, "Cryptanalysis", 1939, Dover.