ти 1

unit UnitMain;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.Menus;

type
  TForm_TI_1 = class(TForm)
    MainMenu: TMainMenu;
    LabelKey: TLabel;
    EditKey: TEdit;
    LabelPlaitext: TLabel;
    ButtonEncryption: TButton;
    RadioButtonDecimationMethod: TRadioButton;
    RadioButtonVigenereCipher: TRadioButton;
    LabelEncryptionType: TLabel;
    OpenDialog: TOpenDialog;
    SaveDialog: TSaveDialog;
    MemoPlainText: TMemo;
    Label1: TLabel;
    ButtonDecryption: TButton;
    MemoCiphertext: TMemo;
    ButFile: TMenuItem;
    ButOpenFile: TMenuItem;
    ButSaveFile: TMenuItem;
    ButInstruction: TMenuItem;
    procedure ButOpenFileClick(Sender: TObject);
    procedure EditKeyChange(Sender: TObject);
    procedure ButtonEncryptionClick(Sender: TObject);
    procedure ButtonDecryptionClick(Sender: TObject);
    procedure ButSaveFileClick(Sender: TObject);
    procedure ButInstructionClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form_TI_1: TForm_TI_1;

implementation

{$R *.dfm}

type
  TLanguage = (TRus, TEng);

function TextToNumbers(text: string; A: Integer): TArray<Integer>;
var
  i: Integer;
begin
  SetLength(Result, Length(text));
  for i := 1 to Length(text) do
  begin
    Result[i - 1] := Ord(UpCase(text[i])) - A;
  end;
end;

function TextToNumbersDecimation(text: string): TArray<Integer>;
var
  i: Integer;
  temp: integer;
begin
  SetLength(Result, Length(text));
  for i := 1 to Length(text) do
  begin
      temp := Ord(text[i]);
      if (temp = 1105) or (temp = 1025) then
          Result[i - 1] := 6
      else
      begin
          if ((temp > 1045) and (temp < 1072)) then
              Result[i - 1] := Ord(UpCase(text[i])) - 1040 + 1;
          if ((temp > 1077) and (temp < 1104)) then
              Result[i - 1] := Ord(UpCase(text[i])) - 1072 + 1;
          if (temp < 1046) then
              Result[i - 1] := Ord(UpCase(text[i])) - 1040;
          if (temp > 1071) and (temp < 1078) then
              Result[i - 1] := Ord(UpCase(text[i])) - 1072;
      end;
  end;
end;

function NumbersToText(numbers: TArray<Integer>; A, M: Integer): string;
var
  i: Integer;
begin
    Result := '';
    for i := 0 to Length(numbers) - 1 do
    begin
        Result := Result + Chr(((numbers[i] + M) mod M) + A);
    end;
end;

function NumbersToTextDecimation(numbers: TArray<Integer>; A, M: Integer): string;
var
  i: Integer;
begin
    Result := '';
    for i := 0 to Length(numbers) - 1 do
    begin
        if numbers[i] = 6 then
            Result := Result + 'Ё'
        else
            Result := Result + Chr(((numbers[i] + M) mod M) + A);
    end;
end;

function EncryptionVigenere(text, key: string): string;
var
  numbers, keyNumbers: TArray<Integer>;
  encrypted: TArray<Integer>;
  i: Integer;
begin
  numbers := TextToNumbersDecimation(text);
  keyNumbers := TextToNumbersDecimation(key);
  SetLength(encrypted, Length(text));
  for i := 0 to Length(text) - 1 do
    encrypted[i] := (numbers[i] + (Ord(key[i mod Length(key) + 1]) - 1040)) mod 33;
  Result := NumbersToTextDecimation(encrypted, 1040, 33);
end;

function DecryptionVigenere(encryptedText, key: string): string;
var
  numbers, keyNumbers: TArray<Integer>;
  decrypted: TArray<Integer>;
  i: Integer;
begin
  numbers := TextToNumbersDecimation(encryptedText);
  keyNumbers := TextToNumbersDecimation(key);
  SetLength(decrypted, Length(encryptedText));
  for i := 0 to Length(encryptedText) - 1 do
    decrypted[i] := (numbers[i] - (Ord(key[i mod Length(key) + 1]) - Ord('А'))) mod 33;
  Result := NumbersToTextDecimation(decrypted, Ord('А') + 848, 33);
end;

function EncryptionDecimationMethod(text: string; key: Integer): string;
var
  numbers: TArray<Integer>;
  encryptedNumbers: TArray<Integer>;
  i: Integer;
begin
  numbers := TextToNumbers(text, ord('A'));
  SetLength(encryptedNumbers, Length(numbers));
  for i := 0 to Length(numbers) - 1 do
    encryptedNumbers[i] := (numbers[i] * key) mod 26;
  Result := NumbersToText(encryptedNumbers, Ord('A'), 26);
end;

function ModInverse(a, m: Integer): Integer;
var
  i: Integer;
begin
  a := a mod m;
  for i := 1 to m do
    if (a * i) mod m = 1 then
      Exit(i);
  Result := -1;
end;

function DecryptionDecimationMethod(encryptedText: string; key: Integer): string;
var
  numbers: TArray<Integer>;
  decryptedNumbers: TArray<Integer>;
  inverseKey: Integer;
  i: Integer;
begin
  numbers := TextToNumbers(encryptedText, ord('A'));
  inverseKey := ModInverse(key, 26);
  if inverseKey = -1 then
  begin
    ShowMessage('Невозможно найти обратный ключ.');
    Exit('');
  end;
  SetLength(decryptedNumbers, Length(numbers));
  for i := 0 to Length(numbers) - 1 do
    decryptedNumbers[i] := (numbers[i] * inverseKey) mod 26;
  Result := NumbersToText(decryptedNumbers, Ord('A'), 26);
end;

procedure CheckAndCorrectText(var Text: TMemo; Lang: TLanguage);
var
    I, J: Integer;
    Buf: String;
    A: Char;
    B: Integer;
begin

    for I := 0 to Text.Lines.Count - 1 do
    begin
        Buf := '';
        for J := 1 to Length(Text.Lines[I]) do
        begin
            case (Lang) of
                TRus:
                begin
                    A := Text.Lines[i][j];
                    B := Ord(A);
                    if (B = 1025) or (B = 1105) or ((B >= 1040) and (B <= 1103)) or (B = 32) then
                    begin
                        Buf := Buf + Text.Lines[I][J];
                    end;
                end;
                TEng:
                begin
                    if (Text.Lines[I][J] in ['A'..'Z','a'..'z', ' ']) then
                    begin
                        Buf := Buf + Text.Lines[I][J];
                    end;
                end;
            end;
        end;
        Text.Lines[i] := (Buf);
    end;
end;

procedure TForm_TI_1.ButInstructionClick(Sender: TObject);
begin
    ShowMessage('Метод децимаций: текст на английском, ключ - число. Алгоритм Виженера: текст на русском, ключ - слово.');
end;

procedure TForm_TI_1.ButOpenFileClick(Sender: TObject);
var
    Path, InputStr, Error: String;
    F: TextFile;
    IsCorrect: Boolean;
begin
    if (OpenDialog.Execute) then
    begin
        Path := OpenDialog.FileName;
        AssignFile(F, Path);
        try
            Reset(F);
            try
                while not(EoF(F)) do
                begin
                    Readln(F, InputStr);
                    if not(InputStr.IsEmpty) then
                    begin
                        MemoPlainText.Lines.Insert(MemoPlainText.Lines.Count, UTF8ToAnsi(InputStr));
                    end;
                end;
            finally
                CloseFile(F);
            end;
        except
            IsCorrect := false;
            Error := 'Ошибка при считывании данных из файла. ';
            ShowMessage(Error);
        end;
    end;
end;

procedure TForm_TI_1.ButSaveFileClick(Sender: TObject);
Var
    F: TextFile;
    Path: String;
    i: integer;
begin
    If SaveDialog.Execute() Then
    Begin
        Path := SaveDialog.FileName;
        AssignFile(F, Path);
        Try
            Rewrite(F);
            Try
                for I := 0 to MemoCiphertext.Lines.Count - 1 do
                    Writeln(F, MemoCiphertext.Lines[i]);
            Finally
                CloseFile(F);
            End;
        Except
            ShowMessage('Ошибка при записи!');
        End;

    End;
end;

procedure TForm_TI_1.ButtonDecryptionClick(Sender: TObject);
var
    KeyDecimation, i: Integer;
    KeyVigenere, Temp: String;
begin
    MemoCipherText.Clear;
    if (RadioButtonDecimationMethod.Checked) then
    begin
        CheckAndCorrectText(MemoPlaintext, TEng);
        try
            KeyDecimation := StrToInt(EditKey.Text);
            for I := 0 to MemoPlaintext.Lines.Count - 1 do
            begin
                Temp := DecryptionDecimationMethod(MemoPlaintext.Lines[i], KeyDecimation);
                MemoCiphertext.Lines.Insert(MemoCiphertext.Lines.Count, Temp);
            end;
        except
            ShowMessage('Ошибка! Проверьте значение ключа!');
        end;
    end
    else
    begin
        if (RadioButtonVigenereCipher.Checked) then
        begin
            CheckAndCorrectText(MemoPlaintext, TRus);
            KeyVigenere := EditKey.Text;
            for I := 0 to MemoPlaintext.Lines.Count - 1 do
            begin
                Temp := DecryptionVigenere(MemoPlaintext.Lines[i], KeyVigenere);
                MemoCiphertext.Lines.Insert(MemoCiphertext.Lines.Count, Temp);
            end;
        end
        else
            ShowMessage('Не выбран шифр!');
    end;
end;

procedure TForm_TI_1.ButtonEncryptionClick(Sender: TObject);
var
    KeyDecimation, i: Integer;
    KeyVigenere, Temp, A: String;
begin
    MemoCipherText.Clear;
    if (RadioButtonDecimationMethod.Checked) then
    begin
        CheckAndCorrectText(MemoPlaintext, TEng);
        try
            KeyDecimation := StrToInt(EditKey.Text);
            for I := 0 to MemoPlaintext.Lines.Count - 1 do
            begin
                Temp := EncryptionDecimationMethod((MemoPlaintext.Lines[i]), KeyDecimation);
                MemoCiphertext.Lines.Insert(MemoCiphertext.Lines.Count, Temp);
            end;
        except
            ShowMessage('Ошибка! Проверьте значение ключа!');
        end;
    end
    else
    begin
        if (RadioButtonVigenereCipher.Checked) then
        begin
            CheckAndCorrectText(MemoPlaintext, TRus);
            KeyVigenere := EditKey.Text;
            for I := 0 to MemoPlaintext.Lines.Count - 1 do
            begin
                A :=  MemoPlaintext.Lines[i];
                Temp := EncryptionVigenere(A, KeyVigenere);
                MemoCiphertext.Lines.Insert(MemoCiphertext.Lines.Count, Temp);
            end;
        end
        else
            ShowMessage('Не выбран шифр!');
    end;
end;

procedure TForm_TI_1.EditKeyChange(Sender: TObject);
begin
    if (EditKey.Text <> '') then
    begin
        ButtonEncryption.Enabled := true;
        ButtonDecryption.Enabled := true;
    end
    else
    begin
        ButtonEncryption.Enabled := false;
        ButtonDecryption.Enabled := false;
    end;
end;

end.