How to encode or decode password in c# with asp.net

How to encode a password:

private string base64Encode(string sData)
{
try
{

byte[] encData_byte = new byte[sData.Length];
encData_byte = System.Text.Encoding.UTF8.GetBytes(sData);
string encodedData = Convert.ToBase64String(encData_byte);
return encodedData;

}
catch(Exception ex)
{
throw new Exception("Error in base64Encode" + ex.Message);
}
}

How to decode it

public string base64Decode(string sData)
{

System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();
System.Text.Decoder utf8Decode = encoder.GetDecoder();
byte[] todecode_byte = Convert.FromBase64String(sData);
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);
return result;

}

How to use it:

Pass the passwd at the time of registration process to that function and save it in database .at the time of login retrive it and decode it and compare with password entered by user,if satisfy then redirect to another page else will be in correct email or userid or password.

calling function for encode

string pwed = base64encode(val);

calling function for decode

string pwed = base64Decode(val);