Visual Encryption for Securing Air-to-Ground Digital Image Transmission

  • Abdulrahman Al Hadhrami

Student thesis: Master's Thesis


Image and video applications are prevalent in today's world, ranging from social media, all the way to surveillance systems. With the increasing demand of image applications in the recent years, the importance of securing image transmissions continues to increase, which is reflected in the field of image encryption and visual cryptography. The nature of encryption requirements of image applications also evolves, with new constraints and parameters to be factored in for the new types of systems. For example, image size can drastically increase due to higher resolution of wide area surveillance systems. Many encryption schemes exist today that are neither domain-specific, meaning they are not tailored to take advantage of domain-specific benefits nor data type-specific, meaning they are not customized to work with images specifically, and just treat the data as a collection of octets; have very demanding requirements to work ideally; or are not flexible to be selective of the parts of data to be encrypted. Visual cryptography is an interesting and important approach to the encryption of images. It is keyless in nature, because it divides the image into multiple shares that, when combined, reconstruct the original image. In its original formulation, it does not even require a computer for the decryption to be performed. However, using it for transmitting digital images requires computer-managed communication, which may introduce an overhead for communicating the different shares securely in separate channels. Selective encryption is a remarkable method of decreasing the computational overhead of the encryption process, by selecting only parts of the image to actually be encrypted. There are many interesting methodologies for how the selection process is achieved. This work envisages a selective keyless image encryption technique using a single share, which is targeted mainly to wide area surveillance applications. It provides all benefits of visual cryptography being architecturally keyless, while maintaining a single communication channel for sending a single share, and uses selective encryption to encrypt only parts of each image.
Date of AwardMay 2018
Original languageAmerican English
SupervisorErnesto Damiani (Supervisor)


  • Visual Cryptography
  • Image Encryption
  • Selective Encryption
  • Wide Area Surveillance.

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