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XOR based optical encryption with noise performance modeling and application to image transmission over wireless IP lan
Author(s)
Zhang, Bo
Date Issued
2004
Type
Thesis
Publisher
Peninsula Technikon
Abstract
Encryption was used whenever someone wanted to send a secret message to
someone. The quality of the algorithm and key combination were the factors that
ensured the strength of the system. However, until there were some automation one
could not use complex methods for encryption because it simply took too long to
encrypt and decrypt messages (even worse for images), manually. Optical
technologies have recently been employed in encryption. Compared with traditional
computer and electrical systems, optical technologies offer primarily two types of
benefits, namely optical systems have an inherent capability for parallel processing,
that is, rapid transmission of information, and information can be hidden in any of
several dimensions, such as phase or spatial frequency. Optical systems therefore
have an excellent capability for encoding information.
In this project an image encryption technique was developed using exclusive-OR
(XOR) operations in the optical domain before the captured image entered a digital
computer network for further processing. A gray-level image of the object to be
encrypted was converted a binary format and a pixel by pixel exclusive OR operation
was performed on it with a random key-bit by making use of polarization encoding in
LCD technology, before the encrypted binary image was detected by a CCD. The
image may also be used as an input to a computer for comparison with a database.
However, noise alters the encrypted bit and the value of the noisy encrypted bit is no
longer binary. In this research the encryption techniques was evaluated and tested for
applicability to encrypt and decrypt successfully. The noise performance was tested
and compared.
The technique was applied for image transmission over a wireless IP broadband link.
Images (optical and thermal) captured from telemedicine application was transmitted
and decrypted with reasonable success in this application.
someone. The quality of the algorithm and key combination were the factors that
ensured the strength of the system. However, until there were some automation one
could not use complex methods for encryption because it simply took too long to
encrypt and decrypt messages (even worse for images), manually. Optical
technologies have recently been employed in encryption. Compared with traditional
computer and electrical systems, optical technologies offer primarily two types of
benefits, namely optical systems have an inherent capability for parallel processing,
that is, rapid transmission of information, and information can be hidden in any of
several dimensions, such as phase or spatial frequency. Optical systems therefore
have an excellent capability for encoding information.
In this project an image encryption technique was developed using exclusive-OR
(XOR) operations in the optical domain before the captured image entered a digital
computer network for further processing. A gray-level image of the object to be
encrypted was converted a binary format and a pixel by pixel exclusive OR operation
was performed on it with a random key-bit by making use of polarization encoding in
LCD technology, before the encrypted binary image was detected by a CCD. The
image may also be used as an input to a computer for comparison with a database.
However, noise alters the encrypted bit and the value of the noisy encrypted bit is no
longer binary. In this research the encryption techniques was evaluated and tested for
applicability to encrypt and decrypt successfully. The noise performance was tested
and compared.
The technique was applied for image transmission over a wireless IP broadband link.
Images (optical and thermal) captured from telemedicine application was transmitted
and decrypted with reasonable success in this application.
Additional information
Thesis (MTech (Information Technology))--Peninsula Technikon, 2004
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