In this dissertation we try to achieve secrecy enhancement in communications by resorting
to both cryptographic and information theoretic secrecy tools and metrics. Our objective
is to unify tools and measures from cryptography community with techniques and metrics
from information theory community that are utilized to provide privacy and confidentiality
in communication systems. For this purpose we adopt encryption techniques accompanied
with privacy amplification tools in order to achieve secrecy goals that are determined based
on information theoretic and cryptographic metrics.
Every secrecy scheme relies on a certain advantage for legitimate users over adversaries
viewed as an asymmetry in the system to deliver the required security for data transmission.
In all of the proposed schemes in this dissertation, we resort to either inherently existing asymmetry in the system or proactively created advantage for legitimate users over a passive eavesdropper to further enhance secrecy of the communications. This advantage is manipulated by means of privacy amplification and encryption tools to achieve secrecy goals for the
system evaluated based on information theoretic and cryptographic metrics.
In our first work discussed in Chapter 2 and the third work explained in Chapter 4, we
rely on a proactively established advantage for legitimate users based on eavesdroppers lack of knowledge about a shared source of data. Unlike these works that assume an errorfree
physical channel, in the second work discussed in Chapter 3 correlated erasure wiretap
channel model is considered. This work relies on a passive and internally existing advantage
for legitimate users that is built upon statistical and partial independence of eavesdroppers channel errors from the errors in the main channel. We arrive at this secrecy advantage for legitimate users by exploitation of an authenticated but insecure feedback channel.
From the perspective of the utilized tools, the first work discussed in Chapter 2 considers
a specific scenario where secrecy enhancement of a particular block cipher called Data Encryption
standard (DES) operating in cipher feedback mode (CFB) is studied. This secrecy enhancement is achieved by means of deliberate noise injection and wiretap channel encoding as a technique for privacy amplification against a resource constrained eavesdropper. Compared to the first work, the third work considers a more general framework in terms of both metrics and secrecy tools. This work studies secrecy enhancement of a general cipher based on universal hashing as a privacy amplification technique against an unbounded adversary. In this work, we have achieved the goal of exponential secrecy where information leakage to adversary, that is assessed in terms of mutual information as an information theoretic measure and Eves distinguishability as a cryptographic metric, decays at an exponential rate. In the second work generally encrypted data frames are transmitted through Automatic Repeat reQuest (ARQ) protocol to generate a common random source between legitimate users that later on is transformed into information theoretically secure keys for encryption by means of privacy amplification based on universal hashing.
Towards the end, future works as an extension of the accomplished research in this dissertation
are outlined. Proofs of major theorems and lemmas are presented in the Appendix.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-06042013-134734 |
| Date | 18 June 2013 |
| Creators | Sowti Khiabani, Yahya |
| Contributors | Wei, Shuangqing, Naraghi-Pour, Morteza, Liang, Xue-Bin, Gu, Guoxiang, Pawlowski, Suzanne D. |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-06042013-134734/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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