check sum

Question

how can i generate checksum for given input so that i can store it in database and match again later. kindly give some example with code to explain.

Sunny Sharma · Answer

then it all should belong to how you're hashing the things up. If you're using MD5 and you use same string to hash, it will yeild the same result every time, that's the purpose of MD5 and how it works. See the sample below, as many time you run it, it will produce the same hash: -------------------------------------------------------- static void Main(string[] args) { MD5 md5 = MD5.Create(); byte[] hash = md5.ComputeHash(Encoding.UTF8.GetBytes("Sunny" + "Kumar")); foreach (byte b in hash) { Console.Write(b.ToString("X2")); } Console.ReadLine(); } -------------------------------------------------------- Hope it helps. Share your code if problem persists. Happy Coding :)

nishant ranjan · Answer

thanks..

Sunny Sharma · Answer

Hi Niranjan, I think you already know the answer of this question. A Hash cannot be decrypted in any way and this is what hashing fundamental says. So, to re-phrase your answer, the best way is to hash and match, it's not possible to reverse the hash back to actual string. Cheers!!

nishant ranjan · Answer

ok .. its giving the unique number i.e. "82A0C3FE2309B5E8FCD6B209E0A41F94" is there any way to decrypt it, i mean to say that if we have "82A0C3FE2309B5E8FCD6B209E0A41F94" then can i decrypt it to get "Sunny Kumar" is it possible. i know the best way to hash and then match but can we do that. let me know how if possible

nishant ranjan · Answer

see my requirement is that i hv a table with column say rollno,name address,dob,phone... checksum my requirement is that when i insert row then a checksum based on column rollno,name and dob should be generated and store in checksum column of that row i.e, string i=rollno+name+dob; md5.ComputeHash(i); // something like this i am able to generate but each time i am getting new value, so next time when i generate checksum for that row and match with checksum value in that row than it will be differnet. kindly suggest

Sunny Sharma · Answer

Hi Nishant, You may use this class to get the checksum, store it where you like and later check back. ----------------------------------------- public string GetChecksum() { FileStream file = new FileStream(FilePath, FileMode.Open); MD5 md5 = new MD5CryptoServiceProvider(); byte[] computedHash = md5.ComputeHash(file); file.Close(); StringBuilder sb = new StringBuilder(); foreach (byte t in computedHash) { sb.Append(t.ToString("x2")); } return sb.ToString(); } ------------------------------------------ Hope it helps. Cheers!

check sum

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