WIP Windows User Accounts Composite Key integration

ModernKeePassLib/Cryptography/ProtectedData.cs

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+using System;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Windows.Security.Cryptography.DataProtection;
+using Windows.Storage.Streams;
+using ModernKeePassLib.Native;
+
+namespace ModernKeePassLib.Cryptography
+{
+    public static class ProtectedData
+    {
+        public static byte[] Protect(byte[] userData, byte[] optionalEntropy, DataProtectionScope scope)
+        {
+            var provider =
+                new DataProtectionProvider(scope == DataProtectionScope.CurrentUser ? "LOCAL=user" : "LOCAL=machine");
+            // Encode the plaintext input message to a buffer.
+            var buffMsg = userData.AsBuffer();
+
+            // Encrypt the message.
+            IBuffer buffProtected;
+            try
+            {
+                buffProtected = provider.ProtectAsync(buffMsg).GetAwaiter().GetResult();
+            }
+            catch (Exception e)
+            {
+                throw;
+            }
+            
+            return buffProtected.ToArray();
+        }
+
+
+        public static byte[] Unprotect(byte[] userData, byte[] optionalEntropy, DataProtectionScope scope)
+        {
+            var provider =
+                new DataProtectionProvider(scope == DataProtectionScope.CurrentUser ? "LOCAL=user" : "LOCAL=machine");
+            // Decode the encrypted input message to a buffer.
+            var buffMsg = userData.AsBuffer();
+
+            // Decrypt the message.
+            IBuffer buffUnprotected;
+            try
+            {
+                buffUnprotected = provider.UnprotectAsync(buffMsg).GetAwaiter().GetResult();
+            }
+            catch (Exception e)
+            {
+                throw;
+            }
+
+            return buffUnprotected.ToArray();
+        }
+    }
+}