Optical color image encryption based on fingerprint key and phase-shifting digital holography

https://doi.org/10.1016/j.optlaseng.2021.106550Get rights and content

Highlights

  • The fingerprint and three-step phase-shifting digital holography are introduced to implement optical color image encryption.

  • The fingerprint is served as secret key directly.

  • The parameters of chaotic Lozi map, linear canonical transform and Fresnel transform can provide additional security to the proposed encryption scheme.

Abstract

In this paper, an optical color image encryption scheme based on fingerprint key and three-step phase-shifting digital holography is proposed. In the proposed encryption scheme, the fingerprint is served as secret key directly, and the random phase masks generated from the fingerprint using secure hash algorithm and chaotic map are just used as interim variables. With the help of the fingerprint-based random phase masks located in the linear canonical transform domain and the three-step phase-shifting digital holography, the primary color image that is hidden into a greyscale carrier image can be encrypted into three noise-like holograms. Since the fingerprint key shared by the sender and authorized receiver is strongly linked with the user and need not be transmitted via the networks, the security of the proposed encryption scheme will be enhanced greatly. In addition, the parameters of chaotic map and linear canonical transform can also provide additional security to the proposed encryption scheme. Numerical simulations and analysis have been carried out to verify the feasibility, security and robustness of the proposed encryption scheme.

Introduction

With the rapid development of the Internet and modern communication techniques, digital images can be widely spread all over the world via open networks. The protection of image information against illegal copying and distribution has become extremely important. This has led to the extensive study of image encryption, authentication and watermarking techniques. Over the past few years, various image encryption techniques have been proposed [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26]. Among them, optical image encryption techniques have attracted significant interest due to their inherent capability of parallel processing and hiding information in many different dimensions. Among optical image encryption techniques, the double random phase encoding (DRPE) in Fourier transform (FT) domain [5] proposed by Réfrégier and Javidi is the most representative one. In this DRPE-based encryption scheme, the primary image can be encrypted into a noise-like pattern by two statistically independent random phase masks located at the input plane and the Fourier plane, respectively. Subsequently, the DRPE has been successfully extended to some other transform domains, such as the fractional Fourier transform (FrFT) domain [6,7], the Fresnel transform (FrT) domain [8,9], the Gyrator transform (GT) domain [10,11] and the linear canonical transform (LCT) domain [12,13].

Since the cipher image obtained by the DRPE-based encryption scheme is complex valued, it is necessary to use the digital holography to record both the amplitude and phase information of the cipher image. Meng et al. [14] and Li [15] proposed two grayscale image encryption schemes in which a two-step phase-shifting digital holography with an arbitrary known phase step was used to record the cipher images encrypted by the DRPE in FrT domain and GT domain, respectively. Li et al. [16] proposed a binary/greyscale image encryption scheme in which the cipher image encrypted by the DRPE in FrT domain is first recorded as two on-axis quadrature-phase holograms by a two-step-only quadrature phase-shifting digital holography, and then compressed to a one-dimensional signal using compressive sensing. Muniraj et al. [17] proposed a robust encryption technique by combining the photon-counted imaging with a classical quadratic phase-based in-line digital holographic system, in which the position-phase-shifting digital holography was used to record the photon-limited cipher image encrypted by the DRPE in LCT domain. Su et al. [18] proposed an image/video encryption scheme in which a single shot digital holography was used to record the cipher image encrypted by the chaos-based random phase encoding (CRPE) in cascaded FrT domain.

For most of the DRPE-based encryption schemes mentioned above, the secret keys are not strongly linked with the user. If the secret keys are lost or stolen, the security of the encryption schemes will be threatened. To avoid this type of threat, the fingerprint biometric features which can be used for user authentication have been introduced to enhance the security of DRPE-based encryption schemes. Verma et al. proposed a symmetric encryption scheme [19] and an asymmetric encryption scheme [20] by combining the biometric keys with the DRPE in FT domain and phase-truncated FT, respectively. In these two encryption schemes, the biometric keys are generated from the fingerprint using the digital holography. Zhu et al. [21] proposed a computational ghost imaging encryption scheme based on fingerprint phase mask, in which the phase mask keys were generated from the fingerprint using the digital holography and chaotic Logistic map. Yan et al. [22] proposed an encryption scheme for multi-depth objects based on optical heterodyne technique and fingerprint, in which the encryption keys were derived from the product of the fingerprint and random phase masks. Su et al. [23] proposed a greyscale image encryption scheme based on pattern-illuminated Fourier ptychography and chaotic fingerprint phase mask, in which the random phase mask keys were generated from the fingerprint using the chaotic Duffing map.

In this paper, an optical color image encryption scheme based on fingerprint key and three-step phase-shifting digital holography is proposed. In this proposed encryption scheme, the random phase masks generated from the fingerprint using secure hash algorithm (SHA-256) [24] and chaotic Lozi map [27] are just used as interim variables, and the fingerprint is served as secret key directly. The proposed encryption scheme can provide two security levels for the primary color image. In the first security level, the primary color image is hidden into a greyscale carrier image by the discrete wavelet transform (DWT). And in the second security level, the modified carrier image is first Fresnel transformed, and then encrypted into three noise-like holograms by the fingerprint-based random phase encoding (FRPE) in LCT domain and three-step phase-shifting digital holography. Since the fingerprint shared by the sender and authorized receiver is strongly linked with the user, and need not be transmitted via the open networks, the security of the proposed encryption scheme will be enhanced greatly. The management of the secret key will also become convenient to some extent. Moreover, the parameters of chaotic Lozi map, LCT and FrT can also provide additional security to the proposed encryption scheme. The rest of this paper is organized as follows. In Section 2, the generation process of the fingerprint-based random phase masks, the encryption and decryption process of the proposed encryption scheme will be described in detail. In Section 3, numerical simulations will be carried out to validate the performance of the proposed encryption scheme. Finally, the conclusion will be summarized in Section 4.

Section snippets

Generation of the fingerprint-based random phase masks

The generation process of the fingerprint-based random phase masks mainly comprises the following steps:

  • Step 1: Calculate the hash value of the fingerprint using the SHA-256, and a 256-bit hash value expressed as a hexadecimal number array can be obtained as follows:H=[h1,h2,,h64]

  • Step 2: Use some elements of the array H to generate the initial values of the chaotic Lozi map through the following way:{x=x0+hex2dec(H(hi:hi+7))×1016y=y0+hex2dec(H(hj:hj+7))×1016

  • where i,j=1,257; x0,y0 and x,y

Results and analysis

To verify the feasibility, security and robustness of the proposed encryption scheme, a series of numerical simulations have been conducted on a Matlab R2014a platform. To conduct these numerical simulations, the color image “Baboon” with size of 256 □ 256 shown in Fig. 2(a) is chosen as the primary image to be encrypted. The greyscale image “Barbara” with size of 512 □ 512 shown in Fig. 2(b) is chosen as the carrier image. Fig. 2(c) shows the fingerprint that is acted as the secret key. The

Conclusions

In this paper, we present an optical color image encryption scheme based on fingerprint key and three-step phase-shifting digital holography. In this proposed encryption scheme, the fingerprint serves as secret key directly, and the random phase masks generated from the fingerprint using the hash algorithm and chaotic map are just used as interim variables. Since the fingerprint key shared by the sender and the authorized receiver is strongly linked with the user and need not be transmitted via

Declaration of Competing Interest

The authors declare that there is no conflict of interest regarding the publication of this paper.

Acknowledgments

This work was supported by National Natural Science Foundation of China (61572063 and 61401308), Natural Science Foundation of Hebei Province (F2020201025, F2019201151, F2018210148 and F2016201142), Science Research Project of Hebei Province (BJ2020030, QN2016085 and QN2017306), Foundation of President of Hebei University (XZJJ201909), and Advanced Talents Incubation Program of Hebei University (521000981370). This work was also supported by the High Performance Computing Center of Hebei

References (27)

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