Checksum failure involving AES encryption
Udo Schuermann
udo at ringlord.com
Tue Apr 17 17:49:08 PDT 2012
I've been working on an external tool to decrypt the contents of ODF
containers, but two files in the container consistently fail their
checksum when decrypted with AES256, even though they actually decrypt
perfectly; the other files have no issues with their checksums. I have
been trying to crawl the LO code for hints (esp.
package/source/manifest/ManifestWriter), but am having some difficulty
understanding the finer points of the code. Could someone more familiar
with it have a look at this, please?
The problematic files in the ODF container are "manifest.rdf" and
"Configurations2/accelerator/current.xml".
Only their checksum fails, the data actually decrypts just fine. Other
files in the container have no problems.
The failure happens only with AES-encryption (no issues when using the
Blowfish cipher).
I have not counted out the possibility that I'm doing something
tremendously stupid, but it does seem like a bug in LO to me, and it
would seem to have appeared with the introduction of AES.
For what it's worth, source to my Java tool/library is at
https://github.com/kuschuermann/rltodfjlib
A ready-to-run binary (for Java 1.6+) is at
http://ringlord.com/rltodfjlib.jar
Running it with "java -jar rltodfjlib.jar -v TestAES.odt" will dump
useful information to the console.
Many thanks!
--Udo.
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