C # MD5 file Verification

Private string GetMd5Hash (string pathName)
{
String strResult = "";
String strHashData = "";
Byte [] arrbytHashValue;

System. IO. FileStream oFileStream = null;

System. Security. Cryptography. MD5CryptoServiceProvider oMD5Hasher =
New System. Security. Cryptography. MD5CryptoServiceProvider ();

Try
{
OFileStream = new System. IO. FileStream (pathName, System. IO. FileMode. Open,
System. IO. FileAccess. Read, System. IO. FileShare. ReadWrite );

ArrbytHashValue = oMD5Hasher. ComputeHash (oFileStream); // calculate the hash value of the specified Stream object

OFileStream. Close ();

// A String consisting of a hex pair separated by a hyphen, where each pair represents the corresponding element of the value; for example, F-2C-4A"

StrHashData = System. BitConverter. ToString (arrbytHashValue );

// Replace-
StrHashData = strHashData. Replace ("-","");

StrResult = strHashData;
}

Catch (System. Exception ex)
{
MessageBox. Show (ex. Message );
}
Return strResult;
}