Secure string usage covered with SecureString class and getted values by using 3 different ways

Author: hakanyavaseng

Advanced-C#-Programming/23_SecureString-Memory-Security/23_SecureString-Memory-Security.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>_23_SecureString_Memory_Security</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

Advanced-C#-Programming/23_SecureString-Memory-Security/Program.cs

@@ -0,0 +1,38 @@
+using System.Runtime.InteropServices;
+using System.Security;
+
+Console.WriteLine();
+
+#region Usage of SecureString
+
+string bankCardNumber = "1234 5678 9012 3456";
+SecureString secureBankCardNumber = new();
+
+foreach (char c in bankCardNumber)
+    secureBankCardNumber.AppendChar(c);
+
+secureBankCardNumber.MakeReadOnly();
+
+//secureBankCardNumber.AppendChar('7'); // Throws InvalidOperationException because it is read-only after line 13
+#endregion
+
+#region Getting the value of SecureString
+
+//First way
+IntPtr bstr = Marshal.SecureStringToBSTR(secureBankCardNumber);
+var value = Marshal.PtrToStringUni(bstr);
+Console.WriteLine(value);
+
+//Second way
+IntPtr bstr2 = Marshal.SecureStringToBSTR(secureBankCardNumber);
+var value2 = Marshal.PtrToStringAuto(bstr2);
+Console.WriteLine(value2);
+
+//Third way
+IntPtr bstr3 = Marshal.SecureStringToBSTR(secureBankCardNumber);
+char[] chars = new char[secureBankCardNumber.Length];
+Marshal.Copy(bstr3, chars, 0, secureBankCardNumber.Length);
+string value3 = string.Join("", chars);
+Marshal.ZeroFreeBSTR(bstr3);
+Console.WriteLine(value3);
+#endregion

Advanced-C#-Programming/Advanced-C#-Programming.sln

@@ -43,7 +43,9 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "20_Reflection", "20_Reflect
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "21_IObservable-IObserver", "21_IObservable-IObserver\21_IObservable-IObserver.csproj", "{B287980D-96C5-47DB-B46B-0A34ACB9C9E7}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "22_Random-Number-Generation", "22_Random-Number-Generation\22_Random-Number-Generation.csproj", "{1ECE838F-9763-43FF-9A5C-6CD38DE3D08B}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "22_Random-Number-Generation", "22_Random-Number-Generation\22_Random-Number-Generation.csproj", "{1ECE838F-9763-43FF-9A5C-6CD38DE3D08B}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "23_SecureString-Memory-Security", "23_SecureString-Memory-Security\23_SecureString-Memory-Security.csproj", "{4D10EB63-A912-4DC8-B0FD-EFE48F988554}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
@@ -135,6 +137,10 @@ Global
 		{1ECE838F-9763-43FF-9A5C-6CD38DE3D08B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{1ECE838F-9763-43FF-9A5C-6CD38DE3D08B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{1ECE838F-9763-43FF-9A5C-6CD38DE3D08B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4D10EB63-A912-4DC8-B0FD-EFE48F988554}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4D10EB63-A912-4DC8-B0FD-EFE48F988554}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4D10EB63-A912-4DC8-B0FD-EFE48F988554}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4D10EB63-A912-4DC8-B0FD-EFE48F988554}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE