using System; using System.IO; using System.Text; using System.Collections.Generic; namespace AniNIX.Crypto { public class Substitution : Cipher { public char[] EngCommon = {'e','t','a','o','i','n','s','h','r','d','l','u','c','m','w','f','y','g','p','b','v','k','x','j','q','z'}; public override String Description() { return "Subsitution cipher suite\nKey format is \"E[EEE]=d[ddd]\", where E is the character in the cipher and d is the intended character in the workspace."; } public override String Command() { return "sub"; } public Substitution(Workbench w) : base (w) {} /// /// We should be able to act on a workspace and command line. Most ciphers will sue the same syntax. Those that don't can override. /// /// The current version of the text being worked on. /// The command sequence. /// The updated version of the workSpace public override String RunCommand(String workSpace,String inputText,String[] line) { if (workSpace == null || line == null || line.Length < 2) { Console.Error.WriteLine("Malformed request."); return workSpace; } switch (line[1]) { case "encrypt": return Encrypt(workSpace,inputText,line); case "decrypt": return Decrypt(workSpace,inputText,line); case "try-common": return TryCommon(inputText); case "help": GetHelp(); return workSpace; default: Console.Error.WriteLine("Invalid command. Type help for more."); return workSpace; } } /// /// Show the helptext for this cipher. By default, most ciphers will only have encrypt, decrypt, and help functions. /// /// This is the incoming line and we use it to get the cipher name public override void GetHelp() { Console.WriteLine(String.Format("Help for the {0} cipher suite.\n{1}\n",Command(),Description())); Console.WriteLine("encrypt key[s] -- encrypt with the key[s]\ndecrypt key[s] -- decrypt with the key[s]\ntry-common -- try common sub keys\nhelp -- show this helptext."); } public override String Encrypt(String workSpace, String cipher, String[] line) { if (line.Length < 3) { Console.Error.WriteLine("Bad formatting."); return workSpace; } char[] changed = workSpace.ToCharArray(); for (int i=2; i sortedChars = Analysis.GetMostCommonLetters(workSpace.ToLower()); char[] modified = workSpace.ToLower().ToCharArray(); char replaceChar; for (int i = 0; i < modified.Length; i++) { if (!Char.IsLetter(modified[i])) { continue; } Console.WriteLine(String.Format("Character <{0}> occurs {1}st in frequency, corresponding with <{2}> -- replacing...", modified[i], sortedChars.IndexOf(modified[i].ToString()), EngCommon[sortedChars.IndexOf(modified[i].ToString())])); replaceChar = EngCommon[sortedChars.IndexOf(modified[i].ToString())]; replaceChar = (workSpace[i] == Char.ToLower(workSpace[i])) ? replaceChar : Char.ToUpper(replaceChar); modified[i] = replaceChar; } return new String(modified); } } }