Application of linear block codes in cryptography

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dc.contributor.author Esmaeili, Mostafa
dc.date.accessioned 2019-03-19T18:27:51Z
dc.date.available 2019-03-19T18:27:51Z
dc.date.copyright 2019 en_US
dc.date.issued 2019-03-19
dc.identifier.uri http://hdl.handle.net/1828/10655
dc.description.abstract Recently, there has been a renewed interest in code based cryptosystems. Amongst the reasons for this interest is that they have shown to be resistant to quantum at- tacks, making them candidates for post-quantum cryptosystems. In fact, the National Institute of Standards and Technology is currently considering candidates for secure communication in the post-quantum era. Three of the proposals are code based cryp- tosystems. Other reasons for this renewed interest include e cient encryption and decryption. In this dissertation, new code based cryptosystems (symmetric key and public key) are presented that use high rate codes and have small key sizes. Hence they overcome the drawbacks of code based cryptosystems (low information rate and very large key size). The techniques used in designing these cryptosystems include random bit/block deletions, random bit insertions, random interleaving, and random bit ipping. An advantage of the proposed cryptosystems over other code based cryp- tosystems is that the code can be/is not secret. These cryptosystems are among the rst with this advantage. Having a public code eliminates the need for permutation and scrambling matrices. The absence of permutation and scrambling matrices results in a signi cant reduction in the key size. In fact, it is shown that with simple random bit ipping and interleaving the key size is comparable to well known symmetric key cryptosystems in use today such as Advanced Encryption Standard (AES). The security of the new cryptosystems are analysed. It is shown that they are immune against previously proposed attacks for code based cryptosystems. This is because scrambling or permutation matrices are not used and the random bit ipping is beyond the error correcting capability of the code. It is also shown that having a public code still provides a good level of security. This is proved in two ways, by nding the probability of an adversary being able to break the cryptosystem and showing that this probability is extremely small, and showing that the cryptosystem has indistinguishability against a chosen plaintext attack (i.e. is IND-CPA secure). IND-CPA security is among the primary necessities for a cryptosystem to be practical. This means that a ciphertext reveals no information about the corresponding plaintext other than its length. It is also shown that having a public code results in smaller key sizes. en_US
dc.language English eng
dc.language.iso en en_US
dc.rights Available to the World Wide Web en_US
dc.subject cryptography en_US
dc.subject linear block codes en_US
dc.subject random bit deletion en_US
dc.subject random bit insertion en_US
dc.subject random interleaving en_US
dc.subject code based encryption en_US
dc.subject post-quantum encryption en_US
dc.title Application of linear block codes in cryptography en_US
dc.type Thesis en_US
dc.contributor.supervisor Gulliver, T. Aaron
dc.degree.department Department of Electrical and Computer Engineering en_US
dc.degree.level Doctor of Philosophy Ph.D. en_US
dc.identifier.bibliographicCitation M. Esmaeili and T. A. Gulliver, "Joint channel coding-cryptography based on random insertions and deletions in QC-LDPC codes,'' IET Communications, vol. 9, no. 12, pp. 1555--1560, 2015. en_US
dc.identifier.bibliographicCitation M. Esmaeili, M. Dakhilalian, and T. A. Gulliver, "New secure channel coding scheme based on randomly punctured quasi-cyclic low-density parity check codes," IET Communications, vol. 8, no. 14, pp. 2556--2562, 2014. en_US
dc.identifier.bibliographicCitation M. Esmaeili and T. A. Gulliver, "A secure code based cryptosystem via random insertions, deletions, and errors,'' IEEE Communications Letters, vol. 20, no. 5, pp. 870--873, 2016. en_US
dc.identifier.bibliographicCitation M. Esmaeili, T.A. Gulliver, "Code-based security with random interleaving,'' IET Communications, vol. 11, no. 8, pp. 1195--1198, Jun. 2017. en_US
dc.description.scholarlevel Graduate en_US

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