Method and apparatus for encryption

DETAILED DESCRIPTION The above-discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the method and apparatus of encrypting optical images and storing these images in memory using random phase encoding of the present invention.
In accordance with the present invention, an encryption technique using random phase encoding in both the input plane and the Fourier plane (or a transform plane) is presented.
Each image is encrypted and can be read out by a unique code or a universal code.
The image to be encrypted is first multiplied by a random phase function.
The Fourier transform of the product of the image and the random phase function is then multiplied by another random phase function in the Fourier domain.
Taking the inverse Fourier transform, an encrypted image in the output plane is obtained.
Each encrypted image can be stored in optical memory.
The encrypted image and the memory are stationary white noise if the two encrypting random phase functions are two independent white sequences uniformly distributed.
This makes it very difficult to decrypt the image and the memory without the knowledge of the phase functions used in the encryption.
The encryption process of the present invention can be done optically or electronically with one or two dimensional functions for encryption.
Further, the image can be phase encoded (optically or digitally) prior to the encryption process, with a phase reading technique employed to obtain the original decrypted image.
Also, a joint transform correlator may be used for the encrytion and/or decryption of the present invention.
It will be appreciated that a variety of well known methods can be used to store or display the encrypted images.
Using different keys to decrypt different memory data allows the memory to be distributed through public channels.
Only the keys are needed to be distributed securely.
This allows many users to share the same encrypted memory without losing the security.
The above-discussed and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings