Asymmetric public key cryptosystem using digital holographic encryption method

A novel asymmetric public key cryptographic algorithm is proposed by modifying the conventional RSA public key protocol, which can be optically implemented by using the phase-shifting digital holography. The proposed method involves a two-key encryption scheme so that it provides stronger security than the one-key encryption method. Optically, two unknown randomly generated numbers are changed to digital holograms which are used as public keys for asymmetric cryptography. The generated public keys and cipher texts by using them are Fourier transformed digital holograms with 256 gray level quantized intensities which are recorded on CCDs. The original plain text can be decrypted only with correct pairs of public-private keys and the holographic encryption-decryption keys in the proposed algorithm. The proposed optical schematic has an advantage of producing an enhanced asymmetric public key cryptosystem compared to the conventional RSA cryptosystem. The results of computer simulations verify that the proposed method shows the feasibility of application to an asymmetric public key cryptosystem with high security strength.