Question

I NEED A MATHEMATICAL ALGORITHM FOR A CEASER CHYPER I CREATED. PLEASE HELP ME...THANK YOU!

THE SINGLE-DIGIT KEY IS 14

THE PHRASE IS "GOOD MORNING PROFESSOR"

THE CYPHER IS UCCR ACFBWBU DFCTSGGCF

I DON'T KNOW HOW TO CREATE THE ALGORITHM AND IT CANNOT BE COMPUTER GENERATED.

a. Develop a Caesar cipher-type encryption algorithm with a little more complexity in it. For example, the algorithm could alternatively shift the cleartext letters positive and negative by the amount of the key value. Variations on this are limitless.

b. Select a single-digit key.

14

c. Code a short message using the algorithm and key.

uccr acfbwbu dfctsggcf

d. Give your instructor the algorithm, key, cleartext, and ciphertext.

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My message is Good Morning Professor

Answer 1

01./**

02.* Caesar cipher

03.* @author Pavel Micka

04.*/

05.public class CaesarCipher {

06./**

07.* Shift (the original variant had 3)

08.*/

09.public static final int SHIFT = 3;

10.

11./**

12.* Encrypt using Caesar cipher

13.* @param s string containing only uppercase characters

14.* @return ecrypted string (closed text)

15.*/

16.public static String encipher(String s){

17.StringBuilder builder = new StringBuilder();

18.for(int i = 0; i < s.length(); i ++){

19.if(s.charAt(i) < 65 || s.charAt(i) > 90){ //znak v ASCII

20.throw new IllegalArgumentException("" +

21."The string does not contain only uppercase characters");

22.}

23.//modularly add the shift

24.char enciphered = s.charAt(i) + SHIFT > 90 ? (char)((s.charAt(i) + SHIFT) - 26) : (char)(s.charAt(i) + SHIFT);

25.builder.append(enciphered);

26.}

27.return builder.toString();

28.}

29./**

30.* Decrypt using Caesar cipher

31.* @param s string containing only uppercase characters

32.* @return decrypted string (open text)

33.*/

34.public static String decipher(String s){

35.StringBuilder builder = new StringBuilder();

36.for(int i = 0; i < s.length(); i ++){

37.if(s.charAt(i) < 65 || s.charAt(i) > 90){ //znak v ASCII

38.throw new IllegalArgumentException("" +

39."The string does not contain only uppercase characters");

40.}

41.//modularly subtract the shift

42.char deciphered = s.charAt(i) - SHIFT < 65 ? (char)((s.charAt(i) - SHIFT) + 26) : (char)(s.charAt(i) - SHIFT);

43.builder.append(deciphered);

44.}

45.return builder.toString();

46.}

47.}