title: Key-space analysis of double random phase encryption technique.
abstract: We perform a numerical analysis on the double random phase encryption/decryption 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.
authors.affiliation: College of Engineering, Mathematics, and Physical Sciences, School of Electrical, Electronic, and Mechanical Engineering, University College Dublin, Ireland.
authors.forename: David S
authors.initials: DS
authors.lastname: Monaghan
authors.forename: Unnikrishnan
authors.initials: U
authors.lastname: Gopinathan
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Naughton
authors.forename: John T
authors.initials: JT
authors.lastname: Sheridan