Vulnerability in the WinZip implimentation of AES?

Dave Howe DaveHowe at
Mon May 17 12:37:08 EDT 2004

 Abstract: WinZip is a popular compression utility for Microsoft Windows
computers, the latest version of which is advertised as having
"easy-to-use AES encryption to protect your sensitive data." We exhibit
several attacks against WinZip's new encryption method, dubbed "AE-2" or
"Advanced Encryption, version two." We then discuss secure alternatives.
Since at a high level the underlying WinZip encryption method appears
secure (the core is exactly Encrypt-then-Authenticate using AES-CTR and
HMAC-SHA1), and since one of our attacks was made possible because of the
way that WinZip Computing, Inc.~decided to fix a different security
problem with its previous encryption method AE-1, our attacks further
underscore the subtlety of designing cryptographically secure software.

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