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|Title: ||Constructing highly efficient signcryption with strong anonymity and low message expansion rate|
|Other Titles: ||Gao xiao qian mi : qi ni ming yu di xun xi peng zhang lü zhi jian zao fa|
高效簽密 : 其匿名與低訊息膨脹率之建造法
|Authors: ||Li, Chung Ki (李頌圻)|
|Department: ||Department of Computer Science|
|Degree: ||Master of Philosophy|
|Issue Date: ||2009|
|Publisher: ||City University of Hong Kong|
|Subjects: ||Computer security.|
Data encryption (Computer science)
|Notes: ||CityU Call Number: QA76.9.A25 L526 2009|
viii, 111 p. 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2009.
Includes bibliographical references (p. 104-111)
|Abstract: ||Signcryption is an efficient and powerful cryptographic primitive which can
do encryption and signature in one logical step. Both confidentiality and unforgebility
are the crucial security requirements for signcryption. Besides that
some other security requirements may be needed for practical use. For example,
Boyen defined a security requirement called ciphertext anonymity for
Identity-Based signcryption. This property can assure that all the signcrypted
texts are anonymous, hiding the identities of both sender and receiver. This
feature favors applications like e-voting and e-auction. Due to the importance
of anonymity, many works has been done on building and cryptanalyzing signcryption
schemes with anonymity. However, no provably secure scheme under
the conventional certificate-based public key setting is known yet.
In the very first paper of Signcryption proposed by Zheng in 1997, it mentioned
that signcryption could reduce the cost of traditional sign-then-encrypt
construction. Here, the cost involves both computational cost and message
expansion rate (MER), where MER is a way for measuring the size difference
between the message and the ciphertext. However, most of the signcryption
papers only focus on discussing computational time of their constructions, little
has been addressed on MER, it is not known of a highly efficient signcryption
scheme in terms of MER can be built which is comparable to Zheng’s seminal scheme while reaching the strongest security level ever defined for signcryption
under the conventional certificate based public key setting.
In this thesis, we provide affirmative answers to these two questions. Firstly,
we construct an anonymous signcryption which hides the identities of both
sender and receiver while achieving probably security with the strongest notions.
Furthermore, we address the signer’s anonymity against the verifiers by
proposing a ring signcryption scheme. The scheme ensure that neither any
third parties nor the receiver can tell which member inside the ring actually
generated the ring signcryption. We also provide formal security models and
Secondly, we give a detailed study on MER and propose a novel construction
and two instantiations. This generic construction relies on a special class
of public key encryption schemes which can have the encryption randomness
recovered during decryption. One of our instantiations achieves a comparable
MER and higher security level than Zheng’s original scheme. In particular,
our scheme achieves provable insider security for both confidentiality and unforgebility.
By using a similar idea, we construct another concrete signcryption
scheme which reaches the lowest MER among all the known signcryption
schemes, regardless which public key cryptographic setting we are considering.
Moreover our scheme also achieves the strongest security notions ever defined
namely public verifiability, insider confidentiality and insider unforgebility.
According to our research results, we believe that signcryption schemes
nowadays are efficient and secure enough for application running on low bandwidth
environment and resource limited devices such as smart cards, mobile
phones and pocket pcs.|
|Online Catalog Link: ||http://lib.cityu.edu.hk/record=b2374875|
|Appears in Collections:||CS - Master of Philosophy |
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