Open encrypted pdf issue

[Olek-HZQ]

Summary of the issue

Open encrypted pdf issue

Environment

windows 11

iTextSharp.LGPLv2.Core version: 3.4.17
.NET Core SDK version: .net 6
IDE: vs 2022

Example code/Steps to reproduce:

var reader = new iTextSharp.text.pdf.PdfReader(sourcePdfPath, Encoding.UTF8.GetBytes("password"));

Output:

Message: 
iTextSharp.text.exceptions.UnsupportedPdfException : Unknown encryption type R = 5

Stack Trace: 

PdfReader.readDecryptedDocObj() line 4265
PdfReader.ReadDocObj() line 2907
PdfReader.ReadPdf() line 3138
PdfReader.ctor(String filename, Byte[] ownerPassword) line 161

Exception message: Unknown encryption type R = 5
Full Stack trace:   Stack Trace: 
PdfReader.readDecryptedDocObj() line 4265
PdfReader.ReadDocObj() line 2907
PdfReader.ReadPdf() line 3138
PdfReader.ctor(String filename, Byte[] ownerPassword) line 161