Essential secret image sharing scheme with equal-sized shadows generation

A (t, s, k, n) essential secret image sharing scheme (ESIS) shares a secret image between s essential and n-s non-essential shadows, where t essential shadows and total k shadows are needed to recover the secret image. This paper presents a three-layered structure for ESIS by generating equal-sized essential and non-essential shadows for security to prevent the discovery of essential shadows using only the size difference. In the first layer, two criteria of t essential shadows and totally k shadows are needed. The second and third layers generate essential and non-essential shadows to fit the requirement of the (t, s, k, n) thresholds. The proposed scheme is proved to fit ESIS and equal-sized requirements with properly chosen parameters. Theoretical analysis and experimental results show that the proposed scheme is superior to other schemes on the smallest shadow sizes among equal-sized ESIS schemes.