Optical encryption of digital data

Brackenbury, Linda E. M.; Bell, Kenneth M.

doi:10.1364/ao.39.005374

Cited by 10 publications

(11 citation statements)

References 9 publications

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“…This demand has led to ever faster and more powerful encryption systems being continually developed. Optical encryption [5][6][7][8][9][10][11] is one such solution to this problem. Optical encryption is particularly interesting, as it offers the possibility of high-speed parallel encryption of two-dimensional image data.…”

Section: Introductionmentioning

confidence: 99%

Key-space analysis of double random phase encryption technique

et al. 2007

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We perform a numerical analysis on the double random phase encryption͞decryption technique. The key-space of an encryption technique is the set of possible keys that can be used to encode data using that technique. In the case of a strong encryption scheme, many keys must be tried in any brute-force attack on that technique. Traditionally, designers of optical image encryption systems demonstrate only how a small number of arbitrary keys cannot decrypt a chosen encrypted image in their system. However, this type of demonstration does not discuss the properties of the key-space nor refute the feasibility of an efficient brute-force attack. To clarify these issues we present a key-space analysis of the technique. For a range of problem instances we plot the distribution of decryption errors in the key-space indicating the lack of feasibility of a simple brute-force attack.

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Section: Introductionmentioning

confidence: 99%

Key-space analysis of double random phase encryption technique

et al. 2007

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“…In a system with 256ϫ 256 pixels and 16 quantization levels there are R = 1.6ϫ 10 78,913 possible keys in the key space. The large number of keys that have 10% of the pixels correct is 4.3ϫ 10 9,249 ; however this is only 2.6ϫ 10 −293 % of the total number of keys, R. Clearly this is an extremely small percentage of the total.…”

Section: B Parametermentioning

confidence: 96%

“…Information security based on optical encryption [5][6][7][8][9][10][11][12][13] is of particular interest, as it offers the possibility of highspeed parallel encryption of 2D image data. One such method of optical encryption is known as the double random phase encryption (DRPE) technique [5].…”

Section: Introductionmentioning

confidence: 99%

Statistical investigation of the double random phase encoding technique

et al. 2009

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The amplitude-encoding case of the double random phase encoding technique is examined by defining a cost function as a metric to compare an attempted decryption against the corresponding original input image. For the case when a cipher-text pair has been obtained and the correct decryption key is unknown, an iterative attack technique can be employed to ascertain the key. During such an attack the noise in the output field for an attempted decryption can be used as a measure of a possible decryption key's correctness. For relatively small systems, i.e., systems involving fewer than 5 ϫ 5 pixels, the output decryption of every possible key can be examined to evaluate the distribution of the keys in key space in relation to their relative performance when carrying out decryption. However, in order to do this for large systems, checking every single key is currently impractical. One metric used to quantify the correctness of a decryption key is the normalized root mean squared (NRMS) error. The NRMS is a measure of the cumulative intensity difference between the input and decrypted images. We identify a core term in the NRMS, which we refer to as the difference parameter, d. Expressions for the expected value (or mean) and variance of d are derived in terms of the mean and variance of the output field noise, which is shown to be circular Gaussian. These expressions assume a large sample set (number of pixels and keys). We show that as we increase the number of samples used, the decryption error obeys the statistically predicted characteristic values. Finally, we corroborate previously reported simulations in the literature by using the statistically derived expressions.

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“…Optical encryption [5][6][7][8][9][10][11] is one such form on information security and is particularly interesting as it offers the possibility of high-speed parallel encryption of two dimensional (2-D) image data. *Corresponding author: e-mail: john.sheridan@ucd.ie; Tel:+353-(0) 1-716-1927 Fax:+353-(0)1-283-0921…”

Section: Introductionmentioning

confidence: 99%

Cost function statistical analysis in double random phase encoding

Monaghan

Gopinathan

Situ

et al. 2008

Optics and Photonics for Information Processing II

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We examine the Amplitude-Encoding (AE) case of the Double Random Phase Encoding (DRPE) technique. A cost function is the function we use to evaluate an attempted decryption with our original input image. For systems with a relatively small key-space we can evaluate the output of every key to get an overall idea of the spread of these keys in key-space. However for larger systems this is not practical. Based on a normalised root mean squared cost function we wish to identify expressions for the mean and variance of the output (decrypted) intensity for a sample set of keys in a large system (256x256 pixels).

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Optical encryption of digital data

Cited by 10 publications

References 9 publications

Key-space analysis of double random phase encryption technique

Key-space analysis of double random phase encryption technique

Statistical investigation of the double random phase encoding technique

Cost function statistical analysis in double random phase encoding

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