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Enhance parsing DrmIon files 

Adding support for parsing plaintext in DrmIon files.

This is needed by my kindle project. When downloading an ebook with my package it gives me a metadata file wich is DrmIon encoded. This file containes plaintext instead of encrypted pages.
This commit is contained in:
mkb79 2021-02-22 14:16:15 +01:00
parent 76a47e0dd0
commit fd51422a36
1 changed files with 24 additions and 4 deletions
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28
DeDRM_plugin/ion.py
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@ -993,6 +993,7 @@ class DrmIon(object):
elif self.ion.gettypename() in ["com.amazon.drm.EncryptedPage@1.0", "com.amazon.drm.EncryptedPage@2.0"]:
decompress = False
decrypt = True
ct = None
civ = None
self.ion.stepin()
@ -1006,7 +1007,23 @@ class DrmIon(object):
civ = self.ion.lobvalue()
if ct is not None and civ is not None:
self.processpage(ct, civ, outpages, decompress)
self.processpage(ct, civ, outpages, decompress, decrypt)
self.ion.stepout()
elif self.ion.gettypename() in ["com.amazon.drm.PlainText@1.0", "com.amazon.drm.PlainText@2.0"]:
decompress = False
decrypt = False
plaintext = None
self.ion.stepin()
while self.ion.hasnext():
self.ion.next()
if self.ion.gettypename() == "com.amazon.drm.Compressed@1.0":
decompress = True
if self.ion.getfieldname() == "data":
plaintext = self.ion.lobvalue()
if plaintext is not None:
self.processpage(plaintext, None, outpages, decompress, decrypt)
self.ion.stepout()
self.ion.stepout()
@ -1017,9 +1034,12 @@ class DrmIon(object):
def print_(self, lst):
self.ion.print_(lst)
def processpage(self, ct, civ, outpages, decompress):
aes = AES.new(self.key[:16], AES.MODE_CBC, civ[:16])
msg = pkcs7unpad(aes.decrypt(ct), 16)
def processpage(self, ct, civ, outpages, decompress, decrypt):
if decrypt:
aes = AES.new(self.key[:16], AES.MODE_CBC, civ[:16])
msg = pkcs7unpad(aes.decrypt(ct), 16)
else:
msg = ct
if not decompress:
outpages.write(msg)