[.net] How do I find the PublicKeyToken for a particular dll?

I need to recreate a provider in my web.config file that looks something like this:

<membership defaultProvider="AspNetSqlMemProvider">
  <providers>
    <clear/>
    <add connectionStringName="TRAQDBConnectionString" applicationName="TRAQ" minRequiredPasswordLength="7" minRequiredNonalphanumericCharacters="0"
         name="AspNetSqlMemProvider"
         type="System.Web.Security.SqlMembershipProvider, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"
    />
  </providers>
</membership>

However, I get a runtime error saying this assembly cannot be loaded, and I think it is because I have the wrong PublicKeyToken. How do I look up the PublicKeyToken for my assembly?

Alternatively, am I going entirely the wrong way with this?

Using sn.exe utility:

sn -T YourAssembly.dll

or loading the assembly in Reflector.

Just adding more info, I wasn't able to find sn.exe utility in the mentioned locations, in my case it was in C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\bin

You can also check by following method.

Go to Run : type the path of DLL for which you need public key. You will find 2 files : 1. __AssemblyInfo_.ini 2. DLL file

Open this __AssemblyInfo_.ini file in notepad , here you can see Public Key Token.

I use Windows Explorer, navigate to C:\Windows\assembly , find the one I need. From the Properties you can copy the PublicKeyToken.

This doesn't rely on Visual Studio or any other utilities being installed.

Assembly.LoadFile(@"C:\Windows\Microsoft.NET\Framework\v4.0.30319\system.data.dll").FullName

Will result in

System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089

If you have the DLL added to your project, you can open the csproj file and see the Reference tag.

Example:

<Reference Include="System.Web.Mvc, Version=3.0.0.1, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL" />

sn -T <assembly> in Visual Studio command line. If an assembly is installed in the global assembly cache, it's easier to go to C:\Windows\assembly and find it in the list of GAC assemblies.

On your specific case, you might be mixing type full name with assembly reference, you might want to take a look at MSDN.

As @CRice said you can use the below method to get a list of dependent assembly with publicKeyToken

public static int DependencyInfo(string args) 
{
    Console.WriteLine(Assembly.LoadFile(args).FullName);
    Console.WriteLine(Assembly.LoadFile(args).GetCustomAttributes(typeof(System.Runtime.Versioning.TargetFrameworkAttribute), false).SingleOrDefault());
    try {
        var assemblies = Assembly.LoadFile(args).GetReferencedAssemblies(); 

        if (assemblies.GetLength(0) > 0)
        {
            foreach (var assembly in assemblies)
            {
                Console.WriteLine(" - " + assembly.FullName + ", ProcessorArchitecture=" + assembly.ProcessorArchitecture);             
            }
            return 0;
        }
    }
    catch(Exception e) {
        Console.WriteLine("An exception occurred: {0}", e.Message);
        return 1;
    } 
    finally{}

    return 1;
}

i generally use it as a LinqPad script you can call it as

DependencyInfo("@c:\MyAssembly.dll"); from the code

Answer is very simple use the .NET Framework tools sn.exe. So open the Visual Studio 2008 Command Prompt and then point to the dll’s folder you want to get the public key,

Use the following command,

sn –T myDLL.dll

This will give you the public key token. Remember one thing this only works if the assembly has to be strongly signed.

Example

C:\WINNT\Microsoft.NET\Framework\v3.5>sn -T EdmGen.exe

Microsoft (R) .NET Framework Strong Name Utility  Version 3.5.21022.8
Copyright (c) Microsoft Corporation.  All rights reserved.

Public key token is b77a5c561934e089