In the threshold decryption phase, given that t (or more) participants agree to decrypt a ciphertext c, they follow two steps.
An optical cascaded GT architecture, in which two POM ciphertexts and decryption phase keys are displayed in the input planes of GTs, respectively, can be employed for decryption.
During the decryption phase based on the root or child node, unless v i possesses the required secret shares, the decryption process output ⊥.
Thus, we consider only the encryption and decryption phase and accordingly compare the proposed identity-based cryptographic scheme with [3, 4, 5, 6, 13, 15].
It is to be noted that encryption algorithmic phase and decryption algorithmic phase are the dominating process in terms of computation cost than setup and extract phases as they are executed only once.
For decryption, the key phase mask is fractional transformed and multiplied with the EFJPS and its inverse FRT is calculated.
The asymmetric (decryption) keys, random phase mask, and transformation angle of gyrator transform serve as main keys.
For the decryption, an iterative phase retrieval algorithm, together with a filter operation, is applied to extract the primary color images from the diffraction intensity map.
The individual decryption key, random phase key, asymmetric keys, transformation angles, control parameters, and initial conditions significantly enhance the security of the system and thus ensure the resistance against existing attacks.
To show the advantages of this structured phase mask (SPM) over the random phase mask (RPM), both the encryption and decryption behaviors of the SPM and RPM are compared.
