代做Decryption and encryption is a very useful activity to hide messages or data代写Web开发

Decryption and encryption is a very useful activity to hide messages or data.  Encryption is utilized to store passwords, store user information and in many other means when the sender does not want the message to be easily readable to anyone other than the intended reader.

Your Assignment

You must write a program that can both decrypt and encrypt a single word that is entered by the user.  The initial choice of encryption and decryption is left up to the user. Additionally, the user will enter a value to be utilized when determining how to translate the character.

Alphabetic Positions

Positions start at zero.  If the letter is ‘a’ then its position in the alphabet is 0 and if the letter is ‘c’ the position is 2 and so on through ‘z’.

Algorithm

Acquire the method to perform. (encryption or decryption). 

Check whether the method specified is valid.

Acquire the translation map

If keyword default is entered, utilize the default map.

default map: “zyxwvutsrqponmlkjihgfedcba”

Validate the size of the map (26 characters)

Acquire the word to encrypt or decrypt, validate depending on method

Validate whether the word can be encrypted

All characters in word must be lowercase letters

Validate whether the word can be decrypted

All characters in word exist in map

Perform. encryption or decryption

Encryption: Convert all characters in word to a character in the map

Given a character in the word, calculate its position in the alphabet

Replace the character in the word with the character in map at that position. 

Decryption: Convert all characters in the word by utilizing the discovered map index

Given a character in the word, determine its index in the map string

This is the position of the character in the alphabet!

Add the position to the first character in range of valid characters for a word What is the range of valid characters? Check the validation step. What is the first character in that range?

Hints/Tips

Implement the algorithm in the order that is specified.

If you get to an error point, immediately exit the program (within main just return 0;)

Use only a single map variable, assigning a proper value into it based on user input.

Encryption Example

If your map is "0987654321abcdefghijklmnop" and your word is "abc", then you need to convert the 'a' to '0', 'b' to '9', and 'c' to '8'; because 'a' is the first letter in the alphabet, so it gets converted to the first character in the map.

Output Requirements

A bad operation choice should result in an error line.

Output results should utilize one of the three following key phrases:

Error

Decrypted word

Encrypted word

Potential Errors

invalid method choice.

invalid translation map size.

encryption cannot be performed.

decryption cannot be performed.

Submission

You will submit on CodeCheck.   Once you have submitted and passed all the test cases, take a screenshot showing all the test cases passed and submit the screenshot to canvas.

Example Runs (User input has been bolded and underlined for emphasis)

Example 1

What is the method (encryption or decryption)? encryption

What is the translation map (type 'default' to use default): default

What is the single word to translate: hello

Encrypted word: svool

Example 2

What is the method (encryption or decryption)? decryption

What is the translation map (type 'default' to use default): default

What is the single word to translate: zyx

Decrypted word: abc

Example 3

What is the method (encryption or decryption)? google

Error: invalid method choice.

Example 4

What is the method (encryption or decryption)? encrptn

Error: invalid method choice.

Example 5

What is the method (encryption or decryption)? encryption

What is the translation map (type 'default' to use default): default

What is the single word to translate: 123cat

Error: encryption cannot be performed.

Example 6

What is the method (encryption or decryption)? encryption

What is the translation map (type 'default' to use default): default

What is the single word to translate: cat

Encrypted word: xzg

Example 7

What is the method (encryption or decryption)? encryption

What is the translation map (type 'default' to use default): xyzabcdefghi

Error: invalid translation map size.

Example 8

What is the method (encryption or decryption)? encryption

What is the translation map (type 'default' to use default): xyzabcdefghijklmnopqrstuvw

What is the single word to translate: cat

Encrypted word: zxq

Example 9

What is the method (encryption or decryption)? encryption

What is the translation map (type 'default' to use default): 123defghijklmnopqrstuvwxyz

What is the single word to translate: cat

Encrypted word: 31t

Example 10

What is the method (encryption or decryption)? encryption

What is the translation map (type 'default' to use default): 123defghijklmnopqrstuvwxyz

What is the single word to translate: 4cat

Error: encryption cannot be performed.

Example 11

What is the method (encryption or decryption)? decryption

What is the translation map (type 'default' to use default): default

What is the single word to translate: xzg

Decrypted word: cat

Example 12

What is the method (encryption or decryption)? decryption

What is the translation map (type 'default' to use default): default

What is the single word to translate: 31t

Error: decryption cannot be performed.

Example 13

What is the method (encryption or decryption)? decryption

What is the translation map (type 'default' to use default): 123defgh

Error: invalid translation map size.