An Essential-Participant-Involved Secret Sharing Scheme for Encrypted Compression of JPEG Images

With the rapid development of data sharing technologies, an increasing number of images are being stored on cloud servers, particularly in JPEG format. Existing JPEG encryption-compression methods rely on cryptographic keys, where the loss of keys would irrevocably compromise original image content. To enhance loss tolerance in compressed storage, recent studies have extensively explored image encryption methods combining JPEG compression mechanisms with secret image sharing (SIS) and image steganography. However, current secret sharing schemes are limited to equal-weight participants, restricting their flexibility and general applicability in real-world scenarios. In certain applications, a participant's identity or position may warrant special privileges, requiring their share to carry higher value.To address this, we introduce a Galois field-based ((t, s), k, n) Essential secret image sharing (ESIS) scheme for DCT coefficients during compression, proposing a JPEG encryption-compression framework with core participants. Our method enables hierarchical weighted encryption-sharing under JPEG compression, where core shares become mandatory during reconstruction while achieving sufficiently high visual encryption levels. Compared to existing solutions, the proposed approach offers more flexible encryption strategies, advancing secure JPEG transmission and providing a viable privacy-preserving option for joint JPEG encryption-compression mechanisms. Experimental results confirm full compliance with format requirements.