Can pdfplumber read a copy-protected PDF?

[indigoviolet]

I get an error like this:

File ~/dev/plus/python/.venv/lib/python3.11/site-packages/pdfplumber/pdf.py:93, in PDF.open(cls, path_or_fp, pages, laparams, password, strict_metadata, repair)
     90     path = None
     92 try:
---> 93     return cls(
     94         stream,
     95         path=path,
     96         pages=pages,
     97         laparams=laparams,
     98         password=password,
     99         strict_metadata=strict_metadata,
    100         stream_is_external=stream_is_external,
    101     )
    103 except PSException:
    104     if not stream_is_external:

File ~/dev/plus/python/.venv/lib/python3.11/site-packages/pdfplumber/pdf.py:44, in PDF.__init__(self, stream, stream_is_external, path, pages, laparams, password, strict_metadata)
     41 self.laparams = None if laparams is None else LAParams(**laparams)
     42 self.password = password
---> 44 self.doc = PDFDocument(PDFParser(stream), password=password or "")
     45 self.rsrcmgr = PDFResourceManager()
     46 self.metadata = {}

File ~/dev/plus/python/.venv/lib/python3.11/site-packages/pdfminer/pdfdocument.py:744, in PDFDocument.__init__(self, parser, password, caching, fallback)
    742         id_value = (b"", b"")
    743     self.encryption = (id_value, dict_value(trailer["Encrypt"]))
--> 744     self._initialize_password(password)
    745 if "Info" in trailer:
    746     self.info.append(dict_value(trailer["Info"]))

File ~/dev/plus/python/.venv/lib/python3.11/site-packages/pdfminer/pdfdocument.py:771, in PDFDocument._initialize_password(self, password)
    769 if factory is None:
    770     raise PDFEncryptionError("Unknown algorithm: param=%r" % param)
--> 771 handler = factory(docid, param, password)
    772 self.decipher = handler.decrypt
    773 self.is_printable = handler.is_printable()

File ~/dev/plus/python/.venv/lib/python3.11/site-packages/pdfminer/pdfdocument.py:358, in PDFStandardSecurityHandler.__init__(self, docid, param, password)
    356 self.param = param
    357 self.password = password
--> 358 self.init()
    359 return

File ~/dev/plus/python/.venv/lib/python3.11/site-packages/pdfminer/pdfdocument.py:362, in PDFStandardSecurityHandler.init(self)
    361 def init(self) -> None:
--> 362     self.init_params()
    363     if self.r not in self.supported_revisions:
    364         error_msg = "Unsupported revision: param=%r" % self.param

File ~/dev/plus/python/.venv/lib/python3.11/site-packages/pdfminer/pdfdocument.py:501, in PDFStandardSecurityHandlerV4.init_params(self)
    499 self.cfm = {}
    500 for k, v in self.cf.items():
--> 501     f = self.get_cfm(literal_name(v["CFM"]))
    502     if f is None:
    503         error_msg = "Unknown crypt filter method: param=%r" % self.param

TypeError: 'PDFObjRef' object is not subscriptable

Several other libraries and command line tools (pdftotext, pdfly, Google Chrome) can read and copy text from this PDF. Any suggestions?

[jsvine]

Thanks. Are you able to share the PDF? And is there a password associated with the PDF?

It's possible, based on the helpful traceback you've shared, that the issue stems from pdfminer.six (this library's main dependency), but having the PDF would help figure that out.

[indigoviolet]

Thanks for the response.

Unfortunately I am unable to share the PDF - I haven't found a good way to redact it for sharing (because I cannot annotate it either). I also do not have a password for the PDF.

[jsvine]

Thanks for the follow-up @indigoviolet. For now, I'm going to (unfortunately) assume that this is an issue with pdfminer.six and largely out of pdfplumber's control. If you are able to locate another-but-sharable PDF with similar issues, do reach out.