MD5 file processing

Question

Good morning all,

I'm working on an MD5 file integrity check tool in C#.

How long should it take for a file to be given an MD5 checksum value? For example, if I try to get a 2gb .mpg file, it is taking around 5 mins+ each time. This seems overly long.

Am I just being impatient?

Below is the code I'm running

public string getHash(String @fileLocation)
    {
        FileStream fs = new FileStream(@fileLocation, FileMode.Open);

        HashAlgorithm alg = new HMACMD5();
        byte[] hashValue = alg.ComputeHash(fs);

        string md5Result = "";

        foreach (byte x in hashValue)
        {
            md5Result += x;
        }           

        fs.Close();           

        return md5Result;           
    }

Any suggestions will be appreciated.

Regards

Another time, use a StringBuilder instead of normal string concat. It's waaaay faster :) — f2lollpll, Mar 20 '12 at 19:12

score 7 · Accepted Answer · edited May 23 '17 at 11:55

7

See this on how to calculate file hash value in a most efficient way. You basically have to wrap FileStream into a BufferedStream and than feed that into HMACMD5.ComputeHash(Stream) overload:

HashAlgorithm hmacMd5 = new HMACMD5();
byte[] hash;

using(Stream fileStream = new FileStream(fileLocation, FileMode.Open))
    using(Stream bufferedStream = new BufferedStream(fileStream, 1200000))
        hash = hmacMd5.ComputeHash(bufferedStream);

edited May 23 '17 at 11:55

Community

1
1

answered Aug 28 '09 at 09:15

Anton Gogolev

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Hi Anton, this seems promising however I'm having a few problems trying to implement your solution. Am I right in thinking that BufferedStream wraps FileStream and both are in their own using statements? Also, in your solution, aren't both classes using the same variable 'stream'.. to double check, this is correct? VC# complained about this. Regards – Ric Aug 28 '09 at 10:39
Why are you using HMACMD5 instead of MD5? The former is supposed to be used for validation purposes. – Billy ONeal Apr 20 '10 at 05:33

MD5 file processing

1 Answers1