الملخص

Local networks and the Internet increase day by day, and a large amount of information is transferred across these networks every day resulting in a dramatic increase in the information security threats. Therefore, it was necessary to use the techniques that ensure the security and the confidentiality of the transferred information. Secret writing is a general term which is used to refer to the protection of information from attackers, and it includes two types of widely used technologies: cryptography and steganography. The research has presented a security model that fulfils the requirements of confidentiality and safety of the data transferred between the parties of the communication process. This model includes two phases that aim to provide a high level of confidentiality and security for the secret text. New methods have been used to combine cryptography with steganography to attain a high level of secrecy and security where the secret text was encrypted in an innovative and modified way by encoding DNA (Deoxyribo Nucleic Acid( and hiding the resulting encrypted text inside images by means of EMD) Exploiting Modification Direction) method. This method has been applied on a number of images and texts, and the measurement of PNSR (88.5382, 87.0293, 97.8257), MSE (0.000015, 0.000019, 0.00004), CO (0) and Q-Factor (0.3521,3458,0.3354) values in the resulting hidden images have been yielded good results.