Create MD5 hash from a string

Hash.cs

using System;
using System.Text;
using System.Security.Cryptography;

static public string GetMd5Sum(string str){
    Encoder enc = System.Text.Encoding.Unicode.GetEncoder();

    byte[] unicodeText = new byte[str.Length * 2];
    enc.GetBytes(str.ToCharArray(), 0, str.Length, unicodeText, 0, true);

    MD5 md5 = new MD5CryptoServiceProvider();
    byte[] result = md5.ComputeHash(unicodeText);

    StringBuilder sb = new StringBuilder();
    for (int i=0;i<result.Length;i++)
    {
        sb.Append(result[i].ToString("X2"));
    }
    
    return sb.ToString();
}