diff --git a/4sem/isaip/01/PlayfairCypher/.gitignore b/4sem/isaip/01/PlayfairCypher/.gitignore
new file mode 100644
index 0000000..a0d6a36
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/.gitignore
@@ -0,0 +1,8 @@
+.idea/
+.vscode/
+.vs/
+
+bin/
+obj/
+
+*.user
\ No newline at end of file
diff --git a/4sem/isaip/01/PlayfairCypher/App.axaml b/4sem/isaip/01/PlayfairCypher/App.axaml
new file mode 100644
index 0000000..38963db
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/App.axaml
@@ -0,0 +1,12 @@
+
+
+
+
+
+
+
+
+
diff --git a/4sem/isaip/01/PlayfairCypher/App.axaml.cs b/4sem/isaip/01/PlayfairCypher/App.axaml.cs
new file mode 100644
index 0000000..eab8225
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/App.axaml.cs
@@ -0,0 +1,29 @@
+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Markup.Xaml;
+using PlayfairCypher.ViewModels;
+using PlayfairCypher.Views;
+
+namespace PlayfairCypher
+{
+ public class App : Application
+ {
+ public override void Initialize()
+ {
+ AvaloniaXamlLoader.Load(this);
+ }
+
+ public override void OnFrameworkInitializationCompleted()
+ {
+ if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+ {
+ desktop.MainWindow = new MainWindow
+ {
+ DataContext = new MainWindowViewModel(),
+ };
+ }
+
+ base.OnFrameworkInitializationCompleted();
+ }
+ }
+}
\ No newline at end of file
diff --git a/4sem/isaip/01/PlayfairCypher/Assets/avalonia-logo.ico b/4sem/isaip/01/PlayfairCypher/Assets/avalonia-logo.ico
new file mode 100644
index 0000000..da8d49f
Binary files /dev/null and b/4sem/isaip/01/PlayfairCypher/Assets/avalonia-logo.ico differ
diff --git a/4sem/isaip/01/PlayfairCypher/Models/PlayfairCrypto.cs b/4sem/isaip/01/PlayfairCypher/Models/PlayfairCrypto.cs
new file mode 100644
index 0000000..c416c65
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/Models/PlayfairCrypto.cs
@@ -0,0 +1,161 @@
+// ReSharper disable StringLiteralTypo
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace PlayfairCypher.Models {
+ public class PlayfairCrypto {
+ private static readonly HashSet EnAlphabet = new("ABCDEFGHIKLMNOPQRSTUVWXYZ");
+
+ public string Encrypt(string keyword, string text) {
+ var keyTable = GenerateTable(keyword);
+ var pairs = FormPairs(text);
+
+ var data = new StringBuilder(32);
+
+ foreach (var pair in pairs) {
+ var idx1 = FindCharIndex(ref keyTable, pair[0]);
+ var idx2 = FindCharIndex(ref keyTable, pair[1]);
+
+ var x1 = idx1 / 5; // x for rows
+ var y1 = idx1 % 5; // and y for cols
+ var x2 = idx2 / 5;
+ var y2 = idx2 % 5;
+
+ char c1, c2;
+ if (y1 == y2) {
+ c1 = keyTable[WrapIndex(x1 + 1), y1];
+ c2 = keyTable[WrapIndex(x2 + 1), y1];
+ }
+ else if (x1 == x2) {
+ c1 = keyTable[x1, WrapIndex(y1 + 1)];
+ c2 = keyTable[x1, WrapIndex(y2 + 1)];
+ }
+ else {
+ c1 = keyTable[x1, y2];
+ c2 = keyTable[x2, y1];
+ }
+
+ data.Append(c1).Append(c2);
+ }
+
+ return data.ToString();
+ }
+
+ public string Decrypt(string keyword, string text) {
+ var keyTable = GenerateTable(keyword);
+ var pairs = FormPairs(text);
+
+ var data = new StringBuilder(32);
+
+ foreach (var pair in pairs) {
+ var idx1 = FindCharIndex(ref keyTable, pair[0]);
+ var idx2 = FindCharIndex(ref keyTable, pair[1]);
+
+ var x1 = idx1 / 5; // x for rows
+ var y1 = idx1 % 5; // and y for cols
+ var x2 = idx2 / 5;
+ var y2 = idx2 % 5;
+
+ char c1, c2;
+ if (y1 == y2) {
+ c1 = keyTable[WrapIndex(x1 - 1), y1];
+ c2 = keyTable[WrapIndex(x2 - 1), y1];
+ }
+ else if (x1 == x2) {
+ c1 = keyTable[x1, WrapIndex(y1 - 1)];
+ c2 = keyTable[x1, WrapIndex(y2 - 1)];
+ }
+ else {
+ c1 = keyTable[x1, y2];
+ c2 = keyTable[x2, y1];
+ }
+
+ data.Append(c1).Append(c2);
+ }
+
+ return data.ToString();
+ }
+
+ private char[,] GenerateTable(string keyword) {
+ char[,] table = new char[5,5];
+
+ keyword = ClearKeyword(keyword);
+ for (var i = 0; i < keyword.Length; i++) {
+ table[i / 5,i % 5] = keyword[i];
+ }
+
+ var kwcSet = new HashSet(keyword);
+ var autoAlphabet = EnAlphabet.Except(kwcSet).ToList();
+ for (var i = keyword.Length; i < 25; i++) {
+ table[i / 5,i % 5] = autoAlphabet[i-keyword.Length];
+ }
+
+ return table;
+ }
+
+ private static string ClearKeyword(string keyword) {
+ string data = "";
+
+ keyword = keyword.Replace("J", "I");
+ foreach (var kwc in keyword) {
+ if (!EnAlphabet.Contains(kwc) || kwc == ' ' || data.Contains(kwc)) {
+ continue;
+ }
+
+ data += kwc;
+ }
+
+ return data;
+ }
+
+ private static int FindCharIndex(ref char[,] table, char c) {
+ for (var i = 0; i < 25; i++) {
+ if (table[i / 5, i % 5] == c) {
+ return i;
+ }
+ }
+
+ throw new ArgumentOutOfRangeException($"Character '{c}' not fount in table");
+ }
+
+ private static List FormPairs(string text) {
+ List data = new ();
+
+ text = text.Replace("J", "I");
+ var cc = text[0];
+ for (var i = 1; i < text.Length; i++) {
+ if (cc != '\0' && !EnAlphabet.Contains(cc)) {
+ cc = '\0';
+ }
+ if (cc == '\0') {
+ cc = text[i];
+ }
+ else if (cc == text[i]) {
+ data.Add("" + cc + "X");
+ cc = text[i];
+ }
+ else {
+ data.Add("" + cc + text[i]);
+ cc = '\0';
+ }
+ }
+
+ if (cc != '\0') {
+ data.Add("" + cc + "X");
+ }
+
+ return data;
+ }
+
+ private static int WrapIndex(int idx) {
+ if (idx < 0) {
+ idx += 5;
+ }
+
+ return idx % 5;
+ }
+ }
+}
\ No newline at end of file
diff --git a/4sem/isaip/01/PlayfairCypher/PlayfairCypher.csproj b/4sem/isaip/01/PlayfairCypher/PlayfairCypher.csproj
new file mode 100644
index 0000000..39da8f3
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/PlayfairCypher.csproj
@@ -0,0 +1,17 @@
+
+
+ WinExe
+ net5.0
+ enable
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/4sem/isaip/01/PlayfairCypher/PlayfairCypher.sln b/4sem/isaip/01/PlayfairCypher/PlayfairCypher.sln
new file mode 100644
index 0000000..dff9bc5
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/PlayfairCypher.sln
@@ -0,0 +1,16 @@
+
+Microsoft Visual Studio Solution File, Format Version 12.00
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "PlayfairCypher", "PlayfairCypher.csproj", "{5AAEBCD9-0ADD-4C76-B1B4-92569D82970B}"
+EndProject
+Global
+ GlobalSection(SolutionConfigurationPlatforms) = preSolution
+ Debug|Any CPU = Debug|Any CPU
+ Release|Any CPU = Release|Any CPU
+ EndGlobalSection
+ GlobalSection(ProjectConfigurationPlatforms) = postSolution
+ {5AAEBCD9-0ADD-4C76-B1B4-92569D82970B}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+ {5AAEBCD9-0ADD-4C76-B1B4-92569D82970B}.Debug|Any CPU.Build.0 = Debug|Any CPU
+ {5AAEBCD9-0ADD-4C76-B1B4-92569D82970B}.Release|Any CPU.ActiveCfg = Release|Any CPU
+ {5AAEBCD9-0ADD-4C76-B1B4-92569D82970B}.Release|Any CPU.Build.0 = Release|Any CPU
+ EndGlobalSection
+EndGlobal
diff --git a/4sem/isaip/01/PlayfairCypher/Program.cs b/4sem/isaip/01/PlayfairCypher/Program.cs
new file mode 100644
index 0000000..8b03d21
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/Program.cs
@@ -0,0 +1,14 @@
+using Avalonia;
+using Avalonia.ReactiveUI;
+
+namespace PlayfairCypher {
+ internal static class Program {
+ public static void Main(string[] args) {
+ BuildAvaloniaApp().StartWithClassicDesktopLifetime(args);
+ }
+
+ private static AppBuilder BuildAvaloniaApp() {
+ return AppBuilder.Configure().UsePlatformDetect().LogToTrace().UseReactiveUI();
+ }
+ }
+}
\ No newline at end of file
diff --git a/4sem/isaip/01/PlayfairCypher/ViewLocator.cs b/4sem/isaip/01/PlayfairCypher/ViewLocator.cs
new file mode 100644
index 0000000..f7d27af
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/ViewLocator.cs
@@ -0,0 +1,33 @@
+using System;
+using Avalonia.Controls;
+using Avalonia.Controls.Templates;
+using PlayfairCypher.ViewModels;
+using ReactiveUI;
+
+namespace PlayfairCypher
+{
+ public class ViewLocator : IDataTemplate
+ {
+ public bool SupportsRecycling => false;
+
+ public IControl Build(object data)
+ {
+ var name = data.GetType().FullName!.Replace("ViewModel", "View");
+ var type = Type.GetType(name);
+
+ if (type != null)
+ {
+ return (Control) Activator.CreateInstance(type)!;
+ }
+ else
+ {
+ return new TextBlock {Text = "Not Found: " + name};
+ }
+ }
+
+ public bool Match(object data)
+ {
+ return data is ReactiveObject;
+ }
+ }
+}
\ No newline at end of file
diff --git a/4sem/isaip/01/PlayfairCypher/ViewModels/MainWindowViewModel.cs b/4sem/isaip/01/PlayfairCypher/ViewModels/MainWindowViewModel.cs
new file mode 100644
index 0000000..25a4687
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/ViewModels/MainWindowViewModel.cs
@@ -0,0 +1,69 @@
+using System;
+using System.Collections.Generic;
+using System.Reactive.Disposables;
+using System.Text;
+using Avalonia.Controls;
+using PlayfairCypher.Models;
+using ReactiveUI;
+
+namespace PlayfairCypher.ViewModels {
+ public class MainWindowViewModel : ReactiveObject {
+ private string _keyword = "";
+ private string _inputText = "";
+ private string _outputText = "";
+ private bool _isEncrypting = true;
+
+ private readonly PlayfairCrypto _cryptor;
+
+ public MainWindowViewModel() {
+ _cryptor = new PlayfairCrypto();
+ }
+
+ public string Keyword {
+ get => _keyword;
+ set {
+ this.RaiseAndSetIfChanged(ref _keyword, value.ToUpper());
+ CalculateCypher();
+ }
+ }
+
+ public string InputText {
+ get => _inputText;
+ set {
+ this.RaiseAndSetIfChanged(ref _inputText, value.ToUpper());
+ CalculateCypher();
+ }
+ }
+
+ public string OutputText {
+ get => _outputText;
+ set => this.RaiseAndSetIfChanged(ref _outputText, value.ToUpper());
+ }
+
+ public bool IsEncrypting {
+ get => _isEncrypting;
+ set {
+ this.RaiseAndSetIfChanged(ref _isEncrypting, value);
+ InputText = OutputText;
+ }
+ }
+
+ public void ClearForm() {
+ InputText = "";
+ Keyword = "";
+ }
+
+ void CalculateCypher() {
+ if (InputText.Length == 0) {
+ OutputText = "";
+ return;
+ }
+ if (Keyword.Length == 0) {
+ OutputText = "Error: Keyword is empty";
+ return;
+ }
+
+ OutputText = IsEncrypting? _cryptor.Encrypt(Keyword.Trim(), InputText.Trim()) : _cryptor.Decrypt(Keyword.Trim(), InputText.Trim());
+ }
+ }
+}
\ No newline at end of file
diff --git a/4sem/isaip/01/PlayfairCypher/Views/MainWindow.axaml b/4sem/isaip/01/PlayfairCypher/Views/MainWindow.axaml
new file mode 100644
index 0000000..67bf65e
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/Views/MainWindow.axaml
@@ -0,0 +1,33 @@
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/4sem/isaip/01/PlayfairCypher/Views/MainWindow.axaml.cs b/4sem/isaip/01/PlayfairCypher/Views/MainWindow.axaml.cs
new file mode 100644
index 0000000..ffe3db2
--- /dev/null
+++ b/4sem/isaip/01/PlayfairCypher/Views/MainWindow.axaml.cs
@@ -0,0 +1,18 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace PlayfairCypher.Views {
+ public class MainWindow : Window {
+ public MainWindow() {
+ InitializeComponent();
+#if DEBUG
+ this.AttachDevTools();
+#endif
+ }
+
+ private void InitializeComponent() {
+ AvaloniaXamlLoader.Load(this);
+ }
+ }
+}
\ No newline at end of file