Introduction A fundamental objective of cryptography is to enable two persons to communicate over an insecure channel (a public channel such as the internet) in such a way that any other person is unable to recover their message (called the plaintext ) from what is sent in its place over the channel (the ciphertext ). The transformation of the plaintext into the ciphertext is called encryption , or enciphering. Encryption-decryption is the most ancient cryptographic activity (ciphers already existed four centuries b.c.), but its nature has deeply changed with the invention of computers, because the cryptanalysis (the activity of the third person, the eavesdropper, who aims at recovering the message) can use their power. The encryption algorithm takes as input the plaintext and an encryption key K E , and it outputs the ciphertext. If the encryption key is secret, then we speak of conventional cryptography , of private key cryptography , or of symmetric cryptography . In practice, the principle of conventional cryptography relies on the sharing of a private key between the sender of a message (often called Alice in cryptography) and its receiver (often called Bob). If, on the contrary, the encryption key is public, then we speak of public key cryptography . Public key cryptography appeared in the literature in the late 1970s.

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Boolean Models and Methods in Mathematics, Computer Science, and Engineering: Boolean Functions for Cryptography and Error-Correcting Codes

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Handbook of magma functions

Form a privacy perspective most concerns against the common use of biometrics arise from the storage and misuse of biometric data. Biometric cryptosystems and cancelable biometrics represent emerging technologies of biometric template protection addressing these concerns and improving public confidence and acceptance of biometrics. In addition, biometric cryptosystems provide mechanisms for biometric-dependent key-release. In the last years a significant amount of approaches to both technologies have been published. A comprehensive survey of biometric cryptosystems and cancelable biometrics is presented. State-of-the-art approaches are reviewed based on which an in-depth discussion and an outlook to future prospects are given.

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A survey on biometric cryptosystems and cancelable biometrics

We demonstrate a new approach to known-plaintext attack on an optical encryption scheme based on double random phase keys. With this attack an opponent can access both random phase keys with the help of the phase retrieval technique. This demonstration shows that an optical encryption scheme based on double random encoding is vulnerable to known-plaintext attack.

Known-plaintext attack on optical encryption based on double random phase keys

Face recognition is increasingly deployed as a means to unobtrusively verify the identity of people. The widespread use of biometrics raises important privacy concerns, in particular if the biometric matching process is performed at a central or untrusted server, and calls for the implementation of Privacy-Enhancing Technologies. In this paper we propose for the first time a strongly privacy-enhanced face recognition system, which allows to efficiently hide both the biometrics and the result from the server that performs the matching operation, by using techniques from secure multiparty computation. We consider a scenario where one party provides a face image, while another party has access to a database of facial templates. Our protocol allows to jointly run the standard Eigenfaces recognition algorithm in such a way that the first party cannot learn from the execution of the protocol more than basic parameters of the database, while the second party does not learn the input image or the result of the recognition process. At the core of our protocol lies an efficient protocol for securely comparing two Pailler-encrypted numbers. We show through extensive experiments that the system can be run efficiently on conventional hardware.

Privacy-Preserving Face Recognition

The braid groups are infinite non-commutative groups naturally arising from geometric braids The aim of this article is twofold One is to show that the braid groups can serve as a good source to enrich cryptography The feature that makes the braid groups useful to cryptography includes the followings: (i) The word problem is solved via a fast algorithm which computes the canonical form which can be efficiently manipulated by computers (ii) The group operations can be performed efficiently (iii) The braid groups have many mathematically hard problems that can be utilized to design cryptographic primitives The other is to propose and implement a new key agreement scheme and public key cryptosystem based on these primitives in the braid groups The efficiency of our systems is demonstrated by their speed and information rate The security of our systems is based on topological, combinatorial and group-theoretical problems that are intractible according to our current mathematical knowledge The foundation of our systems is quite different from widely used cryptosystems based on number theory, but there are some similarities in design

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New Public-Key Cryptosystem Using Braid Groups

Kwangwoon UniversityDepartment of Electronic Engineering447-1, Wolge-Dong, Nowon-GuSeoul 139-701South KoreaAbstract. We propose a new optical image encryption technique basedon exclusive-OR (XOR) operations for a security system that controls theentrance of authorized persons. The basic idea is that we convert agray-level image to eight bit planes for image encryption. We use theXOR operation that is commonly used such as the well-known encryp-tion method. The input image is encrypted by performing optical XORoperations with the key bit stream that are generated by digital encryp-tion algorithms. The gray level input image is converted to eight bitplanes, which are represented on a liquid crystal device (LCD). The keydata represented on different LCDs is reproduced to eight bit planes by alenslet array. The optical XOR operations between the key data and thebit planes are performed by the polarization encoding method. The re-sults of XOR operations, which are detected by a CCD camera, areconverted to an encrypted gray-level image and the image is used as aninput to the binary phase extraction joint transform correlator (BPEJTC)for comparison with reference images. We present some simulation re-sults that verify the proposed method.

Optical image encryption based on XOR operations

Information Security and Cryptology – ICISC 2004

Most public key cryptosystems have been constructed based on abelian groups up to now. We propose a new public key cryptosystem built on finite non abelian groups in this paper. It is convertible to a scheme in which the encryption and decryption are much faster than other well-known public key cryptosystems, even without no message expansion.

Furthermore a signature scheme can be easily derived from it, while it is difficult to find a signature scheme using a non abelian group.

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New Public Key Cryptosystem Using Finite Non Abelian Groups

Most public key cryptosystems have been constructed based on abelian groups up to now. We propose a new public key cryptosystem built on finite non abelian groups in this paper. It is convertible to a scheme in which the encryption and decryption are much faster than other well-known public key cryptosystems, even without no message expansion. Furthermore a signature scheme can be easily derived from it, while it is difficult to find a signature scheme using a non abelian group.

Choonsik Park

Papers

New Public-Key Cryptosystem Using Braid Groups

Optical image encryption based on XOR operations

Information Security and Cryptology – ICISC 2004

New Public Key Cryptosystem Using Finite Non Abelian Groups

New public key cryptosystem using finite non Abelian groups