String Helper

StringExtension.cs

namespace __NAMESPACE__
{
    using System.Text;
    using System.Security.Cryptography;
    using System.Text.RegularExpressions;

    public static class StringExtension
    {
        public static string StripInvalidUnicodeCharacters(this string str)
        {
            if (string.IsNullOrWhiteSpace(str)) return "";

            var invalidCharactersRegex = new Regex("(" 
                + '\xFFFF' + "|"
                + "[\u0000-\u0008]|[\u000b-\u000c]|[\u000f-\u001f]|[\ud800-\udbff](?![\udc00-\udfff]))|((?<![\ud800-\udbff])[\udc00-\udfff])");
            return invalidCharactersRegex.Replace(str, "");
        }

        public static string TrimLeadingZeros(this string str)
        {
            if (string.IsNullOrWhiteSpace(str)) return "";

            var re = new Regex(@"^\s*0+");
            var output = re.Replace(str, "");
            return output;
        }

        private static string ByteArrayToString(byte[] ba)
        {
            StringBuilder hex = new StringBuilder(ba.Length * 2);
            foreach (byte b in ba)
                hex.AppendFormat("{0:x2}", b);
            return hex.ToString();
        }

        public static string Hash(this string input)
        {
            var saltedInput = "__REPLACE_WITH_YOUR_OWN_SALT_HERE__";
            var temp = Encoding.UTF8.GetBytes(saltedInput);
            using (var sha1 = new SHA1Managed())
            {
                var hash = sha1.ComputeHash(temp);
                return ByteArrayToString(hash);
            }
        }
    }
}