4 ms·
This is interesting. Have you contacted them with your findings? How prevalent are multi-stream docs? Also, they don't discuss discarding any of the initial ke
by NateLawson 16y ago
This is interesting. Have you contacted them with your findings? How prevalent are multi-stream docs?
Also, they don't discuss discarding any of the initial keystream, which means that combined with the block number, this could lead to related-key attacks just as with WEP.
- yuhong 16y agoOh, I forgot to mention that they did use a hash to generate the key, which means that it is not vulnerable to the related-key attacks. "This is interesting. Have you contacted them with your findings? " Yes, I did. I began with David LeBlanc's blog's contact page, and ended up starting an email thread about it. I know they know about it even long before. "How prevalent are multi-stream docs?" Pretty much all encrypted docs are multi-stream. And it is easy to read the streams on Windows, just use the OLE compound storage API.
- yuhong 16y agoBTW, not all data are encrypted in an Office file. Usually only three or four entire streams are encrypted in Word/Excel.