ZIP Attacks with Reduced Known-Plaintext Michael Stay AccessData Corporation 2500 N. University Ave. Ste. 200 Provo, UT 84606 [email protected] published by +Tsehp March 2001 Abstract. In [BK94] Biham and Kocher demonstrated that the PKZIP stream cipher was weak and presented an attack requiring thirteen bytes of plaintext. The deflate algorithm “zippers” now use to compress the plaintext before