Image Stego

Hides UTF-8 text in an image's pixels: a 32-bit length header, then one message bit in the least significant bit of each red, green and blue value, three bits a pixel; the result downloads as a lossless PNG. Decode reads it back; Analyze maps the pixels that differ between two images. Sequential LSB embedding is detectable statistically, as Westfeld and Pfitzmann's chi-square attack showed (1999).

• Andreas Westfeld and Andreas Pfitzmann, “Attacks on Steganographic Systems”, Information Hiding (IH 1999), LNCS 1768 (Springer, 2000), pp. 61–76
• W. Bender, D. Gruhl, N. Morimoto and A. Lu, “Techniques for data hiding”, IBM Systems Journal 35 (3–4), 1996, pp. 313–336