the way to encrypt and decrypt the any string

byte[] encData_byte = new byte[string.Length];

encData_byte = System.Text.Encoding.UTF8.GetBytes(Textbox3.Text);

string encodedData = Convert.ToBase64String(encData_byte);

result= encodedData;

System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();

System.Text.Decoder utf8Decode = encoder.GetDecoder();

byte[] todecode_byte = Convert.FromBase64String(string);

int charCount = utf8Decode.GetCharCount(todecode_byte, 0, todecode_byte.Length);

char[] decoded_char = new char[charCount];

utf8Decode.GetChars(todecode_byte, 0, todecode_byte.Length, decoded_char, 0);

string result = new String(decoded_char);