Attacking and repairing the winZip encryption scheme

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 Encryptthen-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 AE1, our attacks further underscore the subtlety of designing cryptographically secure software. Categories and Subject Descriptors D.4 [Operating Systems]: Security and Protection; E.3 [Data Encryption]: Code Breaking; H.3 [Information Storage and Retrieval]: General. General Terms Security. Keywords WinZip, Zi...

• Type: Conference
• Year: 2004
• Where: CCS
• Authors: Tadayoshi Kohno
• Keywords: CCS 2004, Easy-to-use Aes Encryption, Encryption Method, Security Privacy, WinZip Encryption Method