Microsoft reuses RC4 keys in Office

[Steven M. Bellovin]

http://infoworld.com/article/05/01/19/HNmsofficeflaw_1.html
http://eprint.iacr.org/2005/007.pdf 

When you encrypt a file in MS Office, the program hashes the 
user-supplied password and an IV to produce an RC4 key.  However, if 
you create a second version of the document, it doesn't generate a new 
IV.  The consequences are obvious to readers of this list....

		--Prof. Steven M. Bellovin, http://www.cs.columbia.edu/~smb



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