Optical encryption methods based on double random phase encryption (DRPE) have been shown to be vulnerable to different types of attacks. The Fourier plane random phase mask (RPM), which is the most important key, can be cracked with a single impulse function attack. Such an attack is viable because the Fourier transform of a delta function is a unity function. Formation of a unity function can be avoided if RPMs are placed in front of both lenses in a 4-f optical setup, thereby protecting the DRPE from an impulse attack. We have performed numerical simulations to verify the proposed scheme. Resistance of this scheme is checked against the brute force and the impulse function attacks. The experimental results validate the feasibility of the scheme.
© 2009 Optical Society of America
Fourier Optics and Signal Processing
Original Manuscript: February 2, 2009
Revised Manuscript: March 31, 2009
Manuscript Accepted: April 1, 2009
Published: April 15, 2009
Pramod Kumar, Joby Joseph, and Kehar Singh, "Impulse attack-free four random phase mask encryption based on a 4-f optical system," Appl. Opt. 48, 2356-2363 (2009)