SecureStringHelper.cs

using System;
using System.Runtime.InteropServices;
using System.Security;

namespace NETworkManager.Utilities;

public static class SecureStringHelper
{
    public static string ConvertToString(SecureString secureString)
    {
        var valuePtr = IntPtr.Zero;

        try
        {
            valuePtr = Marshal.SecureStringToGlobalAllocUnicode(secureString);
            return Marshal.PtrToStringUni(valuePtr);
        }
        finally
        {
            Marshal.ZeroFreeGlobalAllocUnicode(valuePtr);
        }
    }

    public static SecureString ConvertToSecureString(string clearText)
    {
        if (clearText == null)
            throw new ArgumentNullException(nameof(clearText));

        var securePassword = new SecureString();

        foreach (var c in clearText)
            securePassword.AppendChar(c);

        securePassword.MakeReadOnly();
        return securePassword;
    }
}