Hiding in encrypted images: a three tier security data hiding technique

This paper presents a new crypto domain data hiding technique based on Intermediate Significant Bit Plane Embedding (ISBPE). The cover image is encrypted; the information to be secured is scrambled, and then embedded in the Intermediate Significant Bit (ISB) planes of encrypted cover image, at the locations determined by a Pseudorandom Address Vector (PAV). The pseudorandom embedding of the scrambled data in the ISB planes of encrypted image results in a three tier security of the data to be secured. The ISBPE embedding results in an important advantage that the proposed scheme becomes completely robust to commonly employed attack of Least Significant Bit (LSB) removal/replacement. A novel concept of embedding a very small size fragile watermark in addition to the secret information has been used which facilitates early tamper detection. This feature could save crucial processor time in critical situations of national security issues/warfare etc. Experimental results show that the proposed scheme is more robust to various signal processing attacks like Joint Picture Expert Group compression, Additive White Gaussian Noise and ‘salt and pepper’ noise as compared to conventional LSB based embedding techniques. Comparison results with some well-known techniques show that besides providing high degree of security and robustness to various malicious attacks the proposed technique is capable of embedding a fairly large amount of secret data in the host image while maintaining a good stego-image quality.