Information Hiding in Deflate Compressed Files

Abstract

Steganography has been used as a way of secret communication such that no third party can suspect the presence of communication link. The media for steganographic communication kept changing on with the advancement in technology over the time. Compressed les and archives can also serve as a medium to carry hidden information. In this research, a popular compression algorithm DEFLATE has been studied and analyzed for information hiding purposes. DEFLATE is implemented with bu ers and multiple ush modes have been provided to avoid bu er latency issues. In this study the ush operation during compression has been exploited to embed additional information inside a le and two schemes for information hiding in DEFLATE compressed les have been proposed. The proposed schemes embed additional information during the compression process of DEFLATE and produce a steganographic compressed cover le with additional information embedded inside it. The proposed information hiding schemes are secure and provide good information hiding capacity. A ratio of size of the compressed le and embeddable data size has been calculated and a threshold value is de ned. The proposed scheme works well with single le compression and information hiding but can be adapted and implemented to communicate secret information over the network using protocols that support DEFLATE compression.