Secure chaos-based substitution with diffusion for highly auto-correlated data in image encryption

researchers. By using chaotic maps based random S-box selection, multiple substitution boxes can be used to reduce the correlation among the adjacent pixels of an image but this key dependent nature of substitution methodology makes it vulnerable to chosen plain text attack (CPA). To address these issues, a substitution methodology based on propagating cipher block chaining (PCBC) with a new diffusion technique has been proposed. PCBC is known to be CPA resistant. The effect of first round diffusion is being transferred to next round of diffusion, when first pixel is replaced by last pixel XORed with first the pixel of image. Extensive analyses indicate that proposed solution is secure and achieves best results.