Hybrid crypto secures images

The challenge to encrypting communications successfully is having a secure way to transmit the key that decrypts the information once it reaches its destination.

Researchers from National Chung Cheng University and National Yunlin University of Science and Technology in Taiwan have devised a way to encrypt in a single communication an image and the secret session key that unlocks the image.

The method could make it easier to provide secure applications like video streaming, teleconferencing, video on demand and electronic commerce over the Web, according to the researchers.

The scheme calls for encrypting using the standard double random phase algorithm that can be decrypted using a session key. The session key is encrypted using a standard public-private key scheme, and embedded in the image.

Public and private keys are two sides of a mathematical problem that is easy to solve one way and difficult to solve the other way. This mathematical oddity makes it possible for a public key to be freely available, but its related private key kept secret. The public key can be used to encrypt messages that can only be decrypted using the recipient's private key.

The recipient extracts the session key, decrypts it using his private key, then uses the session key to decrypt the image.

The crypto system could be used in practical applications in two to five years, according to the researchers. The work appeared in the August, 2003 issue of Optical Engineering.