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Get the MD5 hash of a file in .Net

2 Comments

MSDN has a page on how to get the MD5 hash of a string.

Easy enough, but if you follow their example exactly for a file and use File.ReadAllText() to get the string, you will get the wrong MD5 string for binary files. Instead, use File.ReadAllBytes() to bypass encoding issues. (This also applies to SHA1 hashing.)

private static string GetMD5Hash(string filePath)
        {
            byte[] computedHash = new MD5CryptoServiceProvider().ComputeHash(File.ReadAllBytes(filePath));
            var sBuilder = new StringBuilder();
            foreach (byte b in computedHash)
            {
                sBuilder.Append(b.ToString("x2").ToLower());
            }
            return sBuilder.ToString();
        }

2 thoughts on “Get the MD5 hash of a file in .Net”

  2. Nice example. I’ve used it recently, but maybe consider using a Stream instead of File.ReadAllBytes as this will allow you to handle files bigger than the 2GB internal memory limit.

    Reply

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