Improvement of an Encryption Scheme for Binary Images

Chung and Chang proposed an encryption scheme for binary images based on two-dimensional run-encoding (2DRE) and scan patterns. In this paper, we indicate that their scheme is still not secure and efficient enough. Hence, an improvement scheme is proposed. There are two contributions in the proposed improvement scheme. One is to exchange the sequence of compression and encryption. The other is to adopt XOR and substitution operations for encryption. Hence, the improvements on encryptio n time, compression ratio and security are possible.