Collision in double-phase encryption based on fractional Fourier transform
Guohai Situ, Giancarlo Pedrini, Wolfgang Osten · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2009
Collision is a situation that occurs when two or more distinct inputs into a security system produce identical outputs, which is undesirable in security applications such as watermarking and authentication. In this report we present a study of the collision property of double random-phase encoding (DRPE) in the fractional Fourier (FRT) domain. For a decade, optical security systems operating in the FRT domain is said to have a larger key space and therefore higher security. However we find that it is still possible to produce meaningful collision from the cyphertext or a watermarking embedded in a host image even without any knowledge about the fractional orders or the random phase keys.