只取前面一部分就可以了吧try
            {
                using (FileStream f = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read, 8192))
                {
                    hasher.ComputeHash(f);
                    Byte[] hash = hasher.Hash;
                    foreach (Byte hashByte in hash)
                    {
                        buff.Append(string.Format("{0:x2}", hashByte));
                    }
                }
            }完整代码参考:
File Hash Generator Shell Extension