Framework for Efficient Medical Image Encryption Using Dynamic S-Boxes and Chaotic Maps

Abstract

Protecting patient privacy and medical records is a legal requirement. Traditional encryption methods fall short of handling the large volume of medical image data and their peculiar statistical properties. In this paper, we propose a generic medical image encryption framework based on a novel arrangement of two very efficient constructs, dynamic substitution boxes (S-boxes) and chaotic maps. The arrangement of S-box substitution before and after chaotic substitution is shown to successfully resist chosen plaintext and chosen ciphertext attacks. Special precautions are taken to fend off the reset attack against pseudorandom number generators. We show how to implement the generic framework using any key-dependent dynamic Sbox construction method and any chaotic map. Experimental results show that the proposed framework successfully passes all security tests regardless of the chaotic map used for implementation. Based on speed analysis, we recommend the use of the classical Baker map or Henon map to achieve encryption throughput approaching 90 MB/s on a modern PC without hardware acceleration. INDEX TERMS bijective substitution box, chaotic map, image encryption.

A Novel Parallelizable Chaotic Image Encryption Scheme Based on Elliptic Curves

“…Several image encryption schemes depend on chaotic masking without scrambling such as [6][7][8][9][10][11]. The scheme proposed in [6] generates a chaotic sequence to XOR with plain image pixels and then applies a dynamic S-box substitution to produce the cipher image.…”

“…Evidently, the computational speed of chaotic maps is a crucial factor in determining the throughput of a chaotic encryption scheme. The recent work of [10] studies the performance of several classical and modern chaotic maps for image encryption and compares their computational efficiency. The authors introduced an image encryption framework with provable security characteristics by combining chaotic masking and dynamic substitution boxes.…”

“…The use of dynamic key-dependent S-boxes adds another layer of confusion, which increases key space and improves security of image encryption schemes [42]. The framework of [10] is a recent example of image encryption employing dynamic S-boxes.…”

“…In [11], for instance, the algorithm starts with an initial bijective S-box and uses the generated sequence of pseudorandom numbers to iteratively swap elements of the initial S-box to construct the final S-box. In [10], the algorithm filters repeated numbers out of the sequence to produce a sequence of unique random numbers that represent the final S-box. In [43], a Fisher-Yates shuffle modifies the initial S-box to generate a uniformly distributed random S-box.…”

“…To encrypt a plain image, the sender uses a PRNG to generate a pair of image-dependent nonce values, ( , ). The first nonce value, , is used along with the S-box key, , to construct a dynamic key-dependent S-box, , using any S-box construction method, which satisfies the requirements of efficiency, dynamicity and key-dependence [10]. The other nonce value, , is converted to a random EC point, = , which is added in parallel to the initial point sequence to generate a modified point sequence, ⟨ ⟩ =1 = ⟨ + ⟩ =1 .…”