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Correct user pass padding, fix PDFStream export

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This commit is contained in:
NoDRM 2021-12-27 14:23:26 +01:00
parent c11db59150
commit 80f511ade9
2 changed files with 17 additions and 7 deletions
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1
DeDRM_plugin/__init__.py
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@ -867,6 +867,7 @@ class DeDRM(FileTypePlugin):
elif pdf_encryption == "FOPN_fLock" or pdf_encryption == "FOPN_foweb":
print("{0} v{1}: FileOpen encryption '{2}' is unsupported.".format(PLUGIN_NAME, PLUGIN_VERSION, pdf_encryption))
print("{0} v{1}: Try the standalone script from the 'Tetrachroma_FileOpen_ineptpdf' folder in the Github repo.".format(PLUGIN_NAME, PLUGIN_VERSION))
return path_to_ebook
else:
print("{0} v{1}: Encryption '{2}' is unsupported.".format(PLUGIN_NAME, PLUGIN_VERSION, pdf_encryption))
return path_to_ebook

23
DeDRM_plugin/ineptpdf.py
View File

@ -67,6 +67,7 @@ from io import BytesIO
from decimal import Decimal
import itertools
import xml.etree.ElementTree as etree
import traceback
# Wrap a stream so that output gets flushed immediately
# and also make sure that any unicode strings get
@ -1740,12 +1741,19 @@ class PDFDocument(object):
k = b''.join(bytes([c ^ i]) for c in hash )
x = ARC4.new(k).decrypt(x)
# TODO: remove the padding string from the end of the data!
for ct in range(1, len(x)):
new_x = x[:ct]
enc_key = self.check_user_password(new_x, docid, param)
if enc_key is not None:
return enc_key
# "x" is now the padded user password.
# If we wanted to recover / extract the user password,
# we'd need to trim off the padding string from the end.
# As we just want to get access to the encryption key,
# we can just hand the password into the check_user_password
# as it is, as that function would be adding padding anyways.
# This trick only works with V4 and lower.
enc_key = self.check_user_password(x, docid, param)
if enc_key is not None:
return enc_key
return False
@ -2553,7 +2561,7 @@ class PDFSerializer(object):
### are no longer useful, as we have extracted all objects from
### them. Therefore leave them out from the output.
if obj.dic.get('Type') == LITERAL_OBJSTM and not gen_xref_stm:
self.write('(deleted)')
self.write(b'(deleted)')
else:
data = obj.get_decdata()
self.serialize_object(obj.dic)
@ -2587,6 +2595,7 @@ def decryptBook(userkey, inpath, outpath, inept=True):
serializer.dump(outf)
except Exception as e:
print("error writing pdf: {0}".format(e))
traceback.print_exc()
return 2
return 0