Question

I would like to ask if this hashing technique is good enough for asp.net?

I plan to save the hashed password in a single field called ‘password’ and then hash the user input password on the login page and see if it matches

Here is the code:

public const int SALT_BYTES = 24;
    public const int HASH_BYTES = 24;
    public const int PBKDF2_ITERATIONS = 1000;

    public const int ITERATION_INDEX = 0;
    public const int SALT_INDEX = 1;
    public const int PBKDF2_INDEX = 2;

    /// <summary>
    /// Creates a salted PBKDF2 hash of the password.
    /// </summary>
    /// <param name="password">The password to hash.</param>
    /// <returns>The hash of the password.</returns>
    public static string CreateHash(string password)
    {
        // Generate a random salt
        RNGCryptoServiceProvider csprng = new RNGCryptoServiceProvider();
        byte[] salt = new byte[SALT_BYTES];
        csprng.GetBytes(salt);

        // Hash the password and encode the parameters
        byte[] hash = PBKDF2(password, salt, PBKDF2_ITERATIONS, HASH_BYTES);
        return PBKDF2_ITERATIONS + ":" +
           Convert.ToBase64String(salt) + ":" +
           Convert.ToBase64String(hash);
    }

    /// <summary>
    /// Validates a password given a hash of the correct one.
    /// </summary>
    /// <param name="password">The password to check.</param>
    /// <param name="goodHash">A hash of the correct password.</param>
    /// <returns>True if the password is correct. False otherwise.</returns>
    public static bool ValidatePassword(string password, string goodHash)
    {
        // Extract the parameters from the hash
        char[] delimiter = { ':' };
        string[] split = goodHash.Split(delimiter);
        int iterations = Int32.Parse(split[ITERATION_INDEX]);
        byte[] salt = Convert.FromBase64String(split[SALT_INDEX]);
        byte[] hash = Convert.FromBase64String(split[PBKDF2_INDEX]);

        byte[] testHash = PBKDF2(password, salt, iterations, hash.Length);
        return SlowEquals(hash, testHash);
    }

    /// <summary>
    /// Compares two byte arrays in length-constant time. This comparison
    /// method is used so that password hashes cannot be extracted from 
    /// on-line systems using a timing attack and then attacked off-line.
    /// </summary>
    /// <param name="a">The first byte array.</param>
    /// <param name="b">The second byte array.</param>
    /// <returns>True if both byte arrays are equal. False otherwise.</returns>
    private static bool SlowEquals(byte[] a, byte[] b)
    {
        uint diff = (uint)a.Length ^ (uint)b.Length;
        for (int i = 0; i < a.Length && i < b.Length; i++)
            diff |= (uint)(a[i] ^ b[i]);
        return diff == 0;
    }

    /// <summary>
    /// Computes the PBKDF2-SHA1 hash of a password.
    /// </summary>
    /// <param name="password">The password to hash.</param>
    /// <param name="salt">The salt.</param>
    /// <param name="iterations">The PBKDF2 iteration count.</param>
    /// <param name="outputBytes">The length of the hash to generate, in bytes.</param>
    /// <returns>A hash of the password.</returns>
    private static byte[] PBKDF2(string password, byte[] salt, int iterations, int outputBytes)
    {
        Rfc2898DeriveBytes pbkdf2 = new Rfc2898DeriveBytes(password, salt);

        pbkdf2.IterationCount = iterations;
        return pbkdf2.GetBytes(outputBytes);
    }

If there are ways I can I improve this it would be awesome if you could point out certain codes that I could replace.

The code is from: http://crackstation.net/hashing-security.htm#aspsourcecode

Sir/Ma’am Thank you++ 😀

Answer 1

The code you mentioned above looks good. I did not find any salt though.

I would like to mention following code to generate salted HASH.

See if it can help you out for the same.

 ''' <summary>
''' Gets the hash of the string.
''' </summary>
''' <param name="pPassword">Provided password to encrypt</param>
Private Function GetHash(ByVal pPassword As String) As String
    Dim sHashedString As String
    dim sSalt1 as string = "YourSalt"
    dim sSalt2 as string = "YourSalt"
    Dim sSaltedString = sSalt1 & pPassword & sSalt2

    Try
        sHashedString = ConvertByteArrayToString(New System.Security.Cryptography.SHA1CryptoServiceProvider().ComputeHash(System.Text.ASCIIEncoding.ASCII.GetBytes(sSaltedString)))
    Catch oException As Exception
        sHashedString = String.Empty
    End Try

    Return sHashedString
End Function

''' <summary>
''' Converts the byte array to string.
''' </summary>
''' <param name="arrInput">The arr input.</param><returns></returns>
Private Function ConvertByteArrayToString(ByVal arrInput() As Byte) As String
    Dim i As Integer
    Dim sOutput As New System.Text.StringBuilder(arrInput.Length)

    For i = 0 To arrInput.Length - 1
        sOutput.Append(arrInput(i).ToString("X2"))
    Next

    Return sOutput.ToString()
End Function

You can simply provide password to generate encrypted string.
This function is lighter compared to other functions i tried.
You can simply compare password as string while validating it. No need to add any other functions or methods for validation.