PARTIAL ENCRYPTION OF VIDEO FOR COMMUNICATION AND STORAGE
A THESIS SUBMITTED TO
THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES
OF
THE MIDDLE EAST TECHNICAL UNIVERSITY
BY
TURAN Y¨UKSEL
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
IN
THE DEPARTMENT OF COMPUTER ENGINEERING
SEPTEMBER2003
Approval of the Graduate School of Natural and Applied Sciences.
Prof.Dr.Canan¨Ozgen
Director
I certify that this thesis satisfies all the requirements as a thesis for the degree of Master of Science.
Prof.Dr.Ays¸e Kiper
Head of Department This is to certify that we have read this thesis and that in our opinion it is fully adequate,in scope and quality,as a thesis for the degree of Master of Science.
Assoc.Prof.Dr.G¨ozde Bozda˘gıAkar
Co-Supervisor Prof.Dr.Fatos¸T.Yarman Vural
Supervisor
Examining Committee Members
Prof.Dr.A.Enis C¸etin
Prof.Dr.Fatos¸T.Yarman Vural Assoc.Prof.Dr.G¨ozde Bozda˘gıAkar Dr.Cevat S¸ener
Dr.Meltem Turhan Y¨ondem
ABSTRACT
PARTIAL ENCRYPTION OF VIDEO FOR COMMUNICATION AND STORAGE
Y¨uksel,Turan
M.S.,Department of Computer Engineering
Supervisor:Prof.Dr.Fatos¸T.Yarman Vural
Co-Supervisor:Assoc.Prof.Dr.G¨ozde Bozda˘gıAkar
S EPTEMBER2003,66pages
In this study,a new method is proposed to protect video data through partial en-cryption.Unlike previous methods,the bit rate of the encrypted portion can be controlled.In order to accomplish this task,a simple model for the time to break the partial encryption by a chipertext-only attack is defined.Then,the encrypted bit budget distribution strategy maximizing the time subject to the bitrate constraint is found.An algorithm to estimate the model parameters is constructed and it is then implemented over an MPEG-4natural video codec together with the bit budget distribution strategy.The encoder is tested with various image sequences and the output is analyzed.
In addition to the developed video encryption method,afile format is defined to store encryption related side information.
Keywords:Video Encryption,MPEG-4,IPMP.
¨OZ
˙ILET˙IS¸˙IM VE SAKLAMA˙IC¸˙IN KISM˙I V˙IDEO S¸˙IFRELEME
Y¨uksel,Turan
Y¨uksek Lisans,Bilgisayar M¨uhendisli˘gi B¨ol¨um¨u
Tez Y¨oneticisi:Prof.Dr.Fatos¸T.Yarman Vural
Ortak Tez Y¨oneticisi:Doc¸.Dr.G¨ozde Bozda˘gıAkar
E YL¨UL2003,66sayfa
Bu c¸alıs¸mada,video verisinin kısmi s¸ifreleme yoluyla korunmasıic¸in yeni bir y¨ontem ¨onerilmis¸tir.Daha¨onceki y¨ontemlerden farklıolarak,s¸ifrelenmis¸kısmın boyutu-nun kontrol¨u sa˘glanmıs¸tır.Bunu sa˘glayabilmek ic¸in kısmi s¸ifrelemeyi kırmak ic¸in gereken zamanın basit bir modeli tanımlanmıs¸tır.S¸ifrelenen kısmın b¨uy¨ukl¨u˘g¨u kısıtıaltında modeli enb¨uy¨ukleyen bit b¨utc¸esi da˘gıtımıstratejisi bulunmus¸tur.C¸alıs¸ma, model parametrelerinin kestirimi ic¸in de bir algoritma¨onermektedir.Algoritma ve s¸ifrelenmis¸bit b¨utc¸esi da˘gıtımıstratejisi bir MPEG-4do˘gal video kodlayıcı/c¸¨oz¨uc¨u ¨uzerinde gerc¸eklenmis¸ve c¸es¸itli imge dizilerindeki bit da˘gılımıg¨ozlenmis¸tir.
Video s¸ifreleme y¨onteminin yanısıra,c¸alıs¸mada s¸ifreleme yan bilgilerinin saklan-masıic¸in bir dosya bic¸imi de tanımlanmıs¸tır.
Anahtar Kelimeler:Video S¸ifreleme,MPEG-4,IPMP.
