AES 256 and fix obsoleted KeePass function

Author: N6UDP

KeyManagerUI/Certmanager.cs

@@ -45,9 +45,9 @@ public byte[] EncryptMsg(Byte[] msg, X509Certificate2Collection recipientCerts)
                 //  Instantiate an EnvelopedCms object with the ContentInfo
                 //  above.
                 //  Has default SubjectIdentifierType IssuerAndSerialNumber.
-                //  Has default ContentEncryptionAlgorithm property value
-                //  RSA_DES_EDE3_CBC.
-                EnvelopedCms envelopedCms = new EnvelopedCms(contentInfo);
+                //  Force usage of AES256 instead of 3DES
+                Oid aes256 = Oid.FromFriendlyName("aes256", OidGroup.EncryptionAlgorithm);
+                EnvelopedCms envelopedCms = new EnvelopedCms(contentInfo, new AlgorithmIdentifier(aes256));
 
                 //  Formulate a CmsRecipient object collection that
                 //  represent information about the recipients 

KeyManagerUI/KeyManagerUI.csproj

@@ -9,8 +9,9 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>KeyManagerUI</RootNamespace>
     <AssemblyName>KeyManagerUI</AssemblyName>
-    <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.5.2</TargetFrameworkVersion>
     <FileAlignment>512</FileAlignment>
+    <TargetFrameworkProfile />
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>

KeyManagerUI/KeyManagerUIClass.cs

@@ -147,7 +147,7 @@ byte[] GetExistingKey(IOConnectionInfo ioc)
                 // fall back on opening a local file
                 // FUTURE ENHANCEMENT: allow user to enter a URL and name/pwd as well
 
-                OpenFileDialog ofd = UIUtil.CreateOpenFileDialog("KeePassX509Provider", UIUtil.CreateFileTypeFilter(CertProtKeyFileExtension, "x05KeyFile", true), 1, CertProtKeyFileExtension, false /* multi-select */, true);
+                OpenFileDialog ofd = (OpenFileDialog)UIUtil.CreateOpenFileDialog("KeePassX509Provider", UIUtil.CreateFileTypeFilter(CertProtKeyFileExtension, "x05KeyFile", true), 1, CertProtKeyFileExtension, false /* multi-select */, string.Empty).FileDialog;
 
                 if (ofd.ShowDialog() != DialogResult.OK)
                 {