4356

4104

كارشناسي ارشد

معماري كامپيوتر

اصفهان :دانشگاه صنعتي اصفهان ،دانشكده برق وكامپيوتر

1387

نه ،99،[II]ص : مصور ،جدول ،نمودار

ص.ع.به: فارسي وانگليسي

شاد رخ سماوي

شادرخ سماوي ،محمود مدرس هاشمي

20/12/87

مهدي برنجكوب ،مسعود عمومي

مهندسي برق و كامپيوتر

ID4104

به فارسي وانگليسي: قابل رويت در نسخه ديجيتال

AbstractNowadays with the fast pace of internet growth and more communications among peoplewe see that the security of information exchange has become an important issue Use ofcryptography can provide high levels of security but the characteristics of the encryptedmessage can cause problems and provoke unauthorized access Therefore there is ademand for means of communications with higher levels of security than cryptography One of the suggested secure means of information exchange is steganography This is anart and science of covert communication The main goal of steganography is to establishcommunications without anyone suspecting the existence of the link With all the effortsthat is spent in designing a steganographic algorithm the process of data hiding createsdetectable effects in the cover medium which alters the statistical and visual characteristicsof the medium These effects in turn provoke suspicions of the enemy and hence effortsare initiated to reveal the secret message Consequently next to steganography methodsthere are the so called steganalysis algorithms Some of these steganalysis algorithms aredevised to attack one specific data hiding method On the other hand there are methodsthat use a set of extracted characteristics from the cover and stego media to detect theexistence of the hidden data regardless of the applied steganography method In this research we showed that the slightest alterations to the smooth regions in a stegoimage can reveal the existence of hidden data Hence it is required to perform the hidingin the complex regions of an image To prove this claim steganography was performed inhalftone images as well as in grayscale ones For each type of image a different algorithmis offered Each of the suggested algorithms is independent of the other but both are basedon the complexity issue In other words these algorithms perform the data hiding only inthe complex regions of an image and both are capable of correctly extracting the hiddendata The suggested algorithms are tested against a number of known steganalysisalgorithms The implementation results and our experiments prove the functionality andcorrectness of these methods

شاد رخ سماوي

شادرخ سماوي ،محمود مدرس هاشمي

مهدي برنجكوب ،مسعود عمومي