CRYPTANALYSIS ON SCHWARTZ GRAPHICAL ENCRYPTION METHOD
Yuan-Chung Chin, PeCheng Wang, Jing‐Jang Hwang · Cryptologia · 1993
This paper discusses the chosen-plaintext attack and the known-plaintext attack on a graphical encryption method for encryption of computer data proposed by Charles Schwartz of the University of California at Berkeley in 1991. In cracking the Schwartz encryption method, this paper proposes what we call a mask approach. Using this approach, both chosen-plaintext attack and known-plaintext attack can break the Schwartz method. The mask approach is successful because the Schwartz method uses (1) exclusive-or (xor) operations, and (2) a process that is plaintext-independent.