Compare two text files but one doesn't exist due to permissions - c#-4.0

Question

I am attempting to compare two text files in a Script Task in an SSIS Package. Both files exist in the file system. Both files are in the same directory. However, one does not exist because the permissions setup do not see the file.
The code below is not working. I have tried a few different variations of the code below and the SSIS Package continues to go forward, ultimately failing on a subsequent File System Task because doesn't have access to the file.
I am attempting to capture that the file is not present because the package does not have access to the file, and not because the file isn't there. Originally, I was using File.Exists(), however, that won't work because it returns false whether the file is not there or the package does not have access to it.
string packageName = Dts.Variables["System::PackageName"].Value.ToString();
string taskName = Dts.Variables["System.TaskName"].Value.ToString();
string inputFilePath = Dts.Variables["User::inputFilePath"].Value.ToString();
string processedFilePath = Dts.Variables["User::processedFilePath"].Value.ToString();
bool blnFilesMatch = true;
try
{
int i = 0, j = 0;
// Compare the source and processed files to determine if the contents are different.
using (var f1 = new FileStream(inputFilePath, FileMode.Open))
using (var f2 = new FileStream(processedFilePath, FileMode.Open))
{
do
{
i = f1.ReadByte();
j = f2.ReadByte();
if (i != j)
break;
} while (i != -1 && j != -1);
if (i != j)
blnFilesMatch = false; // Files Differ
else
blnFilesMatch = true; // Files are the same
}
Dts.Variables["User::blnIdenticalFiles"].Value = blnFilesMatch;
Dts.TaskResult = (int)ScriptResults.Success;
}
catch (FileNotFoundException)
{
string tempFileName = "temp_" + packageName + ".txt.";
string tempFilePath = Path.Combine(Path.GetDirectoryName(inputFilePath), tempFileName);
// A file wasn't found. Try to create and delete a temp file to determine whether it was because of permissions or if the file just was not present.
try
{
File.Create(tempFilePath);
File.Delete(tempFilePath);
Dts.Variables["User::blnIdenticalFiles"].Value = false;
}
catch (UnauthorizedAccessException uae)
{
// Permissions cannot create the file.
Dts.Events.FireError(0, packageName + " - " + taskName, uae.Message, string.Empty, 0);
Dts.TaskResult = (int)ScriptResults.Failure;
}
}
catch (Exception ex)
{
Dts.Events.FireError(0, packageName + " - " + taskName, ex.Message, string.Empty, 0);
Dts.TaskResult = (int)ScriptResults.Failure;
}