الفهرس 
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Abstract
Information security has always been important in all aspects of life. It can be all the more important as technology continues to control various operations in the day-to-day life. Cryptography provides a layer of security in cases, where the medium of transmission is susceptible to interception, by translating a message into a form that cannot be read by an unauthorized third party. The work started by studying the old and advanced ciphering and deciphering techniques. Computer programs are designed using the MatlabR2009b language to perform algorithms and to assess their performance. It was found that the Blowfish is the more sophisticated one. Therefore, a development for Blowfish algorithm is introduced to enhance its operation. The ultimate objective presented in this thesis is to develop the Blowfish that is low power, bigb-throughput, real-time, reliable and secure algorithm and in addition to making estimation of algorithms more difficult called Triple-key Blowfish. Triple-key Blowfish is based on repeating the algorithm of the Blowfish three times with three different keys to make the estimation process more difficult to detect the plain text from received cipher text. Generation of the Triple-key Blowfish is explained in the following three steps. The first step is called Key Generation using random value keys to generate new value of p-array and new value of S-box. The second step is encryption with new version of three different Keys, and the third step is decryption using the same three different keys reported previously. A series of experiments was implemented using the developed the Triple-key Blowfis ” algorithm and applied to different types of data (text and Image). In these experiments, the encrypted and decrypted files were the same. Two different tests had used for the developed algorithm and it was found the value of security has been increase approximately 200%.