Hash string in c#

I have a problem when trying get a hash string in c#.

I already tried a few websites, but most of them are using files to get the hash. Others that are for strings are a bit too complex. I found examples for Windows authentication for web like this:

FormsAuthentication.HashPasswordForStoringInConfigFile(tbxPassword.Text.Trim(), "md5")

I need to use a hash to make a string that contains a filename more secure. How can I do that?

Example:

string file  = "username";
string hash = ??????(username); 

Should I use another hashing algorithm and not "md5"?

Solution 1:

using System.Security.Cryptography;

public static byte[] GetHash(string inputString)
{
    using (HashAlgorithm algorithm = SHA256.Create())
        return algorithm.ComputeHash(Encoding.UTF8.GetBytes(inputString));
}

public static string GetHashString(string inputString)
{
    StringBuilder sb = new StringBuilder();
    foreach (byte b in GetHash(inputString))
        sb.Append(b.ToString("X2"));

    return sb.ToString();
}

Additional Notes

• Since MD5 and SHA1 are obsolete and insecure algorithms, this solution uses SHA256. Alternatively, you can use BCrypt or Scrypt as pointed out in comments.
• Also, consider "salting" your hashes and use proven cryptographic algorithms, as pointed out in comments.

Solution 2:

The fastest way, to get a hash string for password store purposes, is a following code:

    internal static string GetStringSha256Hash(string text)
    {
        if (String.IsNullOrEmpty(text))
            return String.Empty;

        using (var sha = new System.Security.Cryptography.SHA256Managed())
        {
            byte[] textData = System.Text.Encoding.UTF8.GetBytes(text);
            byte[] hash = sha.ComputeHash(textData);
            return BitConverter.ToString(hash).Replace("-", String.Empty);
        }
    }

Remarks:

• if the method is invoked often, the creation of sha variable should be refactored into a class field;
• output is presented as encoded hex string;

Solution 3:

I don't really understand the full scope of your question, but if all you need is a hash of the string, then it's very easy to get that.

Just use the GetHashCode method.

Like this:

string hash = username.GetHashCode();