ASP.Net Base64 decode & encode yapmak için.

VB.Net kodları
    Public Shared Function base64Encode(inputText As String) As String
        Dim bytesToEncode As Byte() = Encoding.UTF8.GetBytes(inputText)
        Dim encodedText As String = Convert.ToBase64String(bytesToEncode)
        Return encodedText
    End Function

    Public Shared Function basse64Decode(encodedText As String) As String
        Dim decodedBytes As Byte() = Convert.FromBase64String(encodedText)
        Dim decodedText As String = Encoding.UTF8.GetString(decodedBytes)
        Return decodedText
    End Function

C# kodları
public static string base64Encode(string inputText)
{
	byte[] bytesToEncode = Encoding.UTF8.GetBytes(inputText);
	string encodedText = Convert.ToBase64String(bytesToEncode);
	return encodedText;
}

public static string basse64Decode(string encodedText)
{
	byte[] decodedBytes = Convert.FromBase64String(encodedText);
	string decodedText = Encoding.UTF8.GetString(decodedBytes);
	return decodedText;
}