CODEWITHSUNDEEP
c#character-encodingmd5
LoveFortyDown
LoveFortyDown

Reputation: 1021

C# - MD5 hash not matching expected value

I am trying to generate a MD5 hash in C#, but I cannot retrieve the string that I am expecting.

Using an MD5 Hash Generator, the string Hello World! returns a hash of ed076287532e86365e841e92bfc50d8c.

Using this code:

string hash;
using (MD5 md5 = MD5.Create())
{
    hash = Encoding.UTF8.GetString(md5.ComputeHash(Encoding.Default.GetBytes("Hello World!")));
}

returns �\ab�S.�6^����\r� which is problematic.

I suspect this is an issue to do with my encoding of the string. How can I retrieve the expected value?

Edit: As you can see, I do not have much (any) experience with using the MD5 hash - the aim of this question is to educate myself, rather than use the code to secure information.

Upvotes: 2

Views: 2690

Answers (3)

CodeTherapist
CodeTherapist

Reputation: 2806

The ComputeHash() returns a byte array. You have to convert that byte array into a string in hex notation.

public string CalculateMD5Hash(string input)
{
        // step 1, calculate MD5 hash from input
        using(MD5 md5 = System.Security.Cryptography.MD5.Create())
        {
           byte[] inputBytes = System.Text.Encoding.UTF8.GetBytes(input);
           byte[] hash = md5.ComputeHash(inputBytes);

           // step 2, convert byte array to hex string
           StringBuilder sb = new StringBuilder(2 * hash.Length);
           for (int i = 0; i < hash.Length; i++)
           {
              // use "x2" for all lower case.
              sb.Append(hash[i].ToString("X2"));
           }
           return sb.ToString();
        }
}

Upvotes: 2

Dmitrii Bychenko
Dmitrii Bychenko

Reputation: 186728

If you want string represenatation of the hash, you have to encode its byte[] representation:

using System.Security.Cryptography;
...
public string MD5Hash(String input) {
  using (MD5 md5 = MD5.Create()) {
    return String.Concat(md5
      .ComputeHash(Encoding.UTF8.GetBytes(input))
      .Select(item => item.ToString("x2")));
  }
}

...
// hash == "ed076287532e86365e841e92bfc50d8c"
String hash = MD5Hash("Hello World!");

Upvotes: 1

schnaader
schnaader

Reputation: 49719

ComputeHash() returns a byte array. Use a method to convert it to your desired hex format, e.g. BitConverter.ToString and some string manipulatino to get rid of the hyphens:

    string hash;
    using (MD5 md5 = MD5.Create())
    {
        hash = BitConverter.ToString(md5.ComputeHash(Encoding.Default.GetBytes("Hello World!")));
    }
    hash = hash.Replace("-", "");

Output: ED076287532E86365E841E92BFC50D8C

Upvotes: 2

Related Questions