How to Decode a base64 encoded string in C#

The following code sample shows how to Decode a base64 encoded string in C#

public string base64Decode(string data)
{

try {

System.Text.UTF8Encoding encoder = new System.Text.UTF8Encoding();
System.Text.Decoder utf8Decode = encoder.GetDecoder();
byte[] bt= Convert.FromBase64String(data);
int charCount = utf8Decode.GetCharCount(bt, 0, bt.Length);
char[] ch = new char[charCount];
utf8Decode.GetChars(bt, 0, bt.Length, ch , 0);
string result = new String(ch );
return result;
}

catch(Exception e)
{
throw new Exception("Error in base64Decode" + e.Message);
}
}