encrypt or decrypt pdf file

pip install pypdf2

The code:

import PyPDF2
pdfFile = open('example.pdf', 'rb')
pdfReader = PyPDF2.PdfFileReader(pdfFile)
pdfWriter = PyPDF2.PdfFileWriter()
for pageNum in range(pdfReader.numPages):
pdfWriter.addPage(pdfReader.getPage(pageNum))
pdfWriter.encrypt('password')
resultPdf = open('encrypted_output.pdf', 'wb')
pdfWriter.write(resultPdf)
resultPdf.close()