CLR SQL Assembly: Get the Bytestream?

It's just a hex representation of the dll. This bit should do the trick:

    static string GetHexString(string assemblyPath)
    {
        if (!Path.IsPathRooted(assemblyPath))
            assemblyPath = Path.Combine(Environment.CurrentDirectory, assemblyPath);

        StringBuilder builder = new StringBuilder();
        builder.Append("0x");

        using (FileStream stream = new FileStream(assemblyPath,
              FileMode.Open, FileAccess.Read, FileShare.Read))
        {
            int currentByte = stream.ReadByte();
            while (currentByte > -1)
            {
                builder.Append(currentByte.ToString("X2", CultureInfo.InvariantCulture));
                currentByte = stream.ReadByte();
            }
        }

        return builder.ToString();
    }

You should use the resulting string like so:

string hexString = GetHexString(assemblyPath);
string sql = "CREATE ASSEMBLY [" + assemblyName + "] FROM " + hexString + 
             " WITH PERMISSION_SET = " + somePermissionSet;

Found here, the varbinary can be generated without custom code for generating it, only by using SQL Server Management Studio (SSMS) and a local SQL Server instance.

1. create or alter your assembly in your database using its local path on your local SQL Server.

   use yourBase
   go
   create assembly YourAssemblySqlName from N'YourLocalPath\YourAssemblyFile.dll'
   go
   

2. Browse to your assembly in Object Explorer.

   

3. Script its creation.

   

And SSMS gives you the varbinary.