Make the master password decryption about 355% faster by using the Bo…

…uncy Castle library

Tested on a Lumia 640 with a debug build for a db with 5 000 000 rounds :
- 03:38 with the previous method
- 01:01 with Bouncy Castle

Benchmarked on x86 (100 000 rounds, test run 100 times) :
- 47s with the original WinPass method
- 10s with the KeePass desktop client method
- 8s with Bouncy Castle

KeePass.IO/KeePass.IO.csproj

@@ -130,6 +130,10 @@
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>
+    <Reference Include="BouncyCastle.Crypto, Version=1.8.1.0, Culture=neutral, PublicKeyToken=0e99375e54769942">
+      <HintPath>..\packages\BouncyCastle.1.8.1\lib\BouncyCastle.Crypto.dll</HintPath>
+      <Private>True</Private>
+    </Reference>
     <Reference Include="ICSharpCode.SharpZipLib.Portable, Version=0.86.0.51803, Culture=neutral, processorArchitecture=MSIL">
       <HintPath>..\packages\SharpZipLib.Portable.0.86.0.0003\lib\portable-net45+netcore45+wp8+win8+wpa81+MonoTouch+MonoAndroid+Xamarin.iOS10\ICSharpCode.SharpZipLib.Portable.dll</HintPath>
       <Private>True</Private>

KeePass.IO/Utils/PasswordData.cs

@@ -1,10 +1,10 @@
 using System;
-using System.Security.Cryptography;
 using System.Text;
 using KeePass.IO.Data;
 using Windows.Security.Cryptography.Core;
 using Windows.Security.Cryptography;
-using Windows.Storage.Streams;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Crypto.Engines;
 
 namespace KeePass.IO.Utils
 {
@@ -44,23 +44,22 @@ public PasswordData(string password, byte[] keyFile)
 
         public byte[] TransformKey(byte[] transformSeed, int rounds)
         {
+            var block = BufferEx.Clone(_hash);
+
+            var cipher = new AesEngine();
+            cipher.Init(true, new KeyParameter(transformSeed));
+
             var aesEcb = SymmetricKeyAlgorithmProvider
                 .OpenAlgorithm(SymmetricAlgorithmNames.AesEcb);
             var key = aesEcb.CreateSymmetricKey(
                 CryptographicBuffer.CreateFromByteArray(transformSeed));
 
-            IBuffer blockBuffer = CryptographicBuffer
-                .CreateFromByteArray(_hash);
-
-            for (var i = 0; i < rounds; i++)
+            for (int i = 0; i < rounds; i++)
             {
-                blockBuffer = CryptographicEngine
-                    .Encrypt(key, blockBuffer, null);
+                cipher.ProcessBlock(block, 0, block, 0);
+                cipher.ProcessBlock(block, 16, block, 16);
             }
 
-            byte[] block = null;
-            CryptographicBuffer.CopyToByteArray(blockBuffer, out block);
-
             return BufferEx.GetHash(block);
         }
     }

KeePass.IO/packages.config

@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
+  <package id="BouncyCastle" version="1.8.1" targetFramework="wp81" />
   <package id="SharpZipLib.Portable" version="0.86.0.0003" targetFramework="wp81" />
 </packages>