diff --git a/OpenRa.DataStructures/AssetInfo.cs b/OpenRa.DataStructures/AssetInfo.cs
new file mode 100644
index 0000000000..caa072e462
--- /dev/null
+++ b/OpenRa.DataStructures/AssetInfo.cs
@@ -0,0 +1,33 @@
+using System.IO;
+using System.Linq;
+using System.Security.Cryptography;
+
+namespace OpenRa
+{
+	class AssetInfo
+	{
+		public readonly string Filename;
+		public readonly string Hash;
+
+		public AssetInfo(string filename, string hash)
+		{
+			Filename = filename;
+			Hash = hash;
+		}
+
+		static string GetHash(string filename)
+		{
+			using (var csp = SHA1.Create())
+				return new string(csp.ComputeHash(File.ReadAllBytes(filename))
+					.SelectMany(a => a.ToString("x2")).ToArray());
+		}
+
+		public static AssetInfo FromLocalFile(string filename)
+		{
+			return new AssetInfo(filename, GetHash(filename));
+		}
+
+		/* todo: perf: cache this */
+		public bool IsPresent() { return File.Exists(Filename) && (Hash == GetHash(Filename)); }
+	}
+}
diff --git a/OpenRa.DataStructures/OpenRa.DataStructures.csproj b/OpenRa.DataStructures/OpenRa.DataStructures.csproj
index 1fd76608f7..f794fd193f 100644
--- a/OpenRa.DataStructures/OpenRa.DataStructures.csproj
+++ b/OpenRa.DataStructures/OpenRa.DataStructures.csproj
@@ -14,6 +14,7 @@
     <OldToolsVersion>2.0</OldToolsVersion>
     <UpgradeBackupLocation>
     </UpgradeBackupLocation>
+    <TargetFrameworkVersion>v3.5</TargetFrameworkVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
     <DebugSymbols>true</DebugSymbols>
@@ -33,11 +34,15 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
+    <Reference Include="System.Core">
+      <RequiredTargetFramework>3.5</RequiredTargetFramework>
+    </Reference>
     <Reference Include="System.Data" />
     <Reference Include="System.Drawing" />
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="AssetInfo.cs" />
     <Compile Include="float2.cs" />
     <Compile Include="int2.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />