• Proposes SPJEU, a self-sufficient plaintext-related JPEG image encryption scheme that eliminates the need to transmit plaintext-related extra data.
• Uses a unified key to select DC coefficients for homomorphic encryption and group diffusion, with AC coefficients permuted based on run length.
• Resists chosen plaintext attacks while simplifying key management and preserving JPEG format compatibility.
• Achieves minimal file size increment after encryption, balancing security and compression efficiency.