create short string from long string

GetUniqueId.cs

    public static class UtilityFunction
    {
        public static string GetUniqueId(string input)
        {
            string result = string.Empty;
            char[] chars = new char[]
                                {
                                'a','b','c','d','e','f','g','h',
                                'i','j','k','l','m','n','o','p',
                                'q','r','s','t','u','v','w','x',
                                'y','z','0','1','2','3','4','5',
                                '6','7','8','9','A','B','C','D',
                                'E','F','G','H','I','J','K','L',
                                'M','N','O','P','Q','R','S','T',
                                'U','V','W','X','Y','Z'
                                };
            byte[] bytes = Encoding.UTF8.GetBytes(input);
            MD5 md5 = MD5.Create();
            byte[] md5Bytes = md5.ComputeHash(bytes);
            string strMd5Result = BitConverter.ToString(md5Bytes).Replace("-", string.Empty);

            for (int i = 0; i < 1; i++)
            {
                int intMd5SubStr = Convert.ToInt32(strMd5Result.Substring(i * 8, 8), 16);
                Console.WriteLine(intMd5SubStr);

                for (int j = 0; j < 6; j++)
                {
                    int intMask = 31;   //0x001F
                    result += chars[intMask & intMd5SubStr];
                    intMd5SubStr >>= 5;
                }
            }

            return result;
        }
    }