111 lines
4.3 KiB
Plaintext
111 lines
4.3 KiB
Plaintext
using System;
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using System.Linq;
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using System.IO;
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using System.Text;
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using System.Collections.Generic;
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namespace AniNIX.Crypto {
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public class Caesarian : Cipher {
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public override String Description() { return "Caesarian ciphers shift letters by a numeric offset. Key format is thus a number."; }
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public override String Command() { return "caesar"; }
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public Caesarian(Workbench w) : base (w) {}
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/// <summary>
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/// Decode the user's input and relate to an existing function.
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/// </summary>
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/// <param name="workSpace">The working copy of the cipher</param>
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/// <param name="inputText">The original cipher</param>
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/// <param name="line">The user input</param>
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/// <returns>The modified workspace string</returns>
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public override String RunCommand(String workSpace,String inputText,String[] line) {
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if (workSpace == null || line == null || line.Length < 2) {
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Console.Error.WriteLine("Malformed request.");
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return workSpace;
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}
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switch (line[1]) {
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case "encrypt":
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return Encrypt(workSpace,inputText,line);
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case "decrypt":
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return Decrypt(workSpace,inputText,line);
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case "brute":
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BruteForce(workSpace);
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return workSpace;
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default:
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GetHelp();
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return workSpace;
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}
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}
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/// <summary>
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/// Show this help text
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/// </summary>
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public override void GetHelp() {
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Console.WriteLine(String.Format("Help for the {0} cipher suite.\n{1}\n",Command(),Description()));
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Console.WriteLine("caesar encrypt key -- encrypt with the key\ncaesar decrypt key -- decrypt with the key\ncaesar brute -- brute-force for keys\ncaesar help -- show this helptext.");
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}
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/// <summary>
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/// Encrypt a string with the cipher
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/// </summary>
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/// <param name="workSpace">The working copy of the cipher</param>
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/// <param name="inputText">The original cipher</param>
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/// <param name="line">The user input</param>
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/// <returns>The encrypted string</returns>
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public override String Encrypt(String workSpace,String inputText,String[] line) {
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// Validate input
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if (line.Length != 3) {
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Console.Error.WriteLine("Bad formatting");
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return workSpace;
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}
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int rotation = 0;
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try {
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rotation = Int32.Parse(line[2]);
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} catch (Exception e) {
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Console.Error.WriteLine("Error in parsing rotation value -- should be numeric.");
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Console.Error.WriteLine(e.Message);
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return workSpace;
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}
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char[] modified = workSpace.ToCharArray();
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//For each character in the workSpace, rotate it by the offset given.
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for (int i = 0; i < modified.Length; i++) {
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if (Char.IsLetter(modified[i])) {
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int baseC;
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int modC;
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// Have to account for case.
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if (modified[i] < 'a') {
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baseC = (int)'A';
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modC = (int)modified[i] - (int)'A';
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} else {
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baseC = (int)'a';
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modC = (int)modified[i] - (int)'a';
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}
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modC = (modC + rotation)%26;
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modified[i] = (char)(baseC+modC);
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}
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}
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return new String(modified);
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}
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// This is a dummy override.
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public override String Decrypt(String workSpace,String inputText,String[] line) {
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return Encrypt(workSpace,inputText,line);
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}
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/// <summary>
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/// Try rotating through all 26 possible combinations.
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/// </summary>
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public void BruteForce(String workSpace) {
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String[] line = new String[3];
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line[0] = "rot";
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line[1] = "encrypt";
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for (int i=0; i<26; i++) {
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line[2]=i.ToString();
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Console.Write(String.Format("{0,2}: {1}\n",i,Encrypt(workSpace,null,line)));
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}
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}
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}
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}
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