Vulnerability to chosen-cyphertext attacks of optical encryption schemes based on double random phase keys

Universitat de Barcelona, Departament de Física Aplicada i Optica, Diagonal 647, 08028 Barcelona, Spain.
Optics Letters (Impact Factor: 3.29). 08/2005; 30(13):1644-6. DOI: 10.1364/OL.30.001644
Source: PubMed

ABSTRACT We show how optical encryption methods based on double random phase keys are vulnerable to an organized attack of the chosen-ciphertext type. The decryption key can be easily obtained by an opponent who has repeated access to either the encryption or decryption machines. However, we have also devised a solution that prevents the attack. Our results cast doubts on the present security of these techniques.

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    • "On the other hand, in practice, the encryption algorithms can also be realized and implemented in digital forms. In such scenarios, the conventional optical encryption system has shown to be vulnerable to some formulated attacks [25] [26] [27] [28] [29] [30] [31]. "
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    ABSTRACT: In this study, we investigate the integration of compressive sensing (CS) and photon-counting imaging (PCI) techniques with a ptychography-based optical image encryption system. Primarily, the plaintext real-valued image is optically encrypted and recorded via a classical ptychography technique. Further, the sparse-based representations of the original encrypted complex data can be produced by combining CS and PCI techniques with the primary encrypted image. Such a combination takes an advantage of reduced encrypted samples (i.e., linearly projected random compressive complex samples and photon-counted complex samples) that can be exploited to realize optical decryption, which inherently serves as a secret key (i.e., independent to encryption phase keys) and makes an intruder attack futile. In addition to this, recording fewer encrypted samples provides a substantial bandwidth reduction in online transmission. We demonstrate that the fewer sparse-based complex samples have adequate information to realize decryption. To the best of our knowledge, this is the first report on integrating CS and PCI with conventional ptychography-based optical image encryption.
    Journal of optics 06/2015; 17(6). DOI:10.1088/2040-8978/17/6/065704 · 2.06 Impact Factor
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    • "Notice that Fourier transform, Fresnel transform and fractional Fourier transform are all special cases of linear canonical transform (LCT) [7] [8], the concept of LCTbased random phase encoding (LCT-RPE) is used to describe the DRPEs based on them. Cryptanalysis on these exploited LCT-RPE systems has been performed and reported, and it has been well known that known-plaintext attack (KPA) [9] [10], chosen-plaintext attack (CPA) [11] [12] [13] and chosen-ciphertext attack (CCA) [14] pose the greatest security threat. To our knowledge, most of the above reported attack schemes are motivating to reproduce the keys of the optical security systems, and each of them can only deal with one specific security system. "
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    ABSTRACT: We introduce a chosen-plaintext attack scheme on general optical cryptosystems that use linear canonical transform and phase encoding based on correlated imaging. The plaintexts are chosen as Gaussian random real number matrixes, and the corresponding ciphertexts are regarded as prior knowledge of the proposed attack method. To establish the reconstruct of the secret plaintext, correlated imaging is employed using the known resources. Differing from the reported attack methods, there is no need to decipher the distribution of the decryption key. The original secret image can be directly recovered by the attack in the absence of decryption key. In addition, the improved cryptosystems combined with pixel scrambling operations are also vulnerable to the proposed attack method. Necessary mathematical derivations and numerical simulations are carried out to demonstrate the validity of the proposed attack scheme.
    Optics Communications 03/2015; 338. DOI:10.1016/j.optcom.2014.10.050 · 1.45 Impact Factor
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    • "Basically, the motivation of cryptanalysis attacks is to retrieve random phase codes [28] [29] [30] [31] [32] [33]. In our presented work, the random phase codes serve as the system locks and are independent of the ID cards. "
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    ABSTRACT: We introduce a security-enhanced optical verification system using dual phase-only correlation based on a novel correlation algorithm. By employing a nonlinear encoding, the inherent locks of the verification system are obtained in real-valued random distributions, and the identity keys assigned to authorized users are designed as pure phases. The verification process is implemented in two-step correlation, so only authorized identity keys can output the discriminate auto-correlation and cross-correlation signals that satisfy the reset threshold values. Compared with the traditional phase-only-correlation-based verification systems, a higher security level against counterfeiting and collisions are obtained, which is demonstrated by cryptanalysis using known attacks, such as the known-plaintext attack and the chosen-plaintext attack. Optical experiments as well as necessary numerical simulations are carried out to support the proposed verification method.
    Journal of optics 02/2015; 17(2). DOI:10.1088/2040-8978/17/2/025703 · 2.06 Impact Factor
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