The anonymous channels have been the essence of numerous protocols that include anonymous message passing between peers. The mixnet structure is one way to accomplish the anonymity . Since the publication of the Chaumian mixnet, there have been many practical implementations. There are two main approaches to implement mixnets: the decryption (Chaumian) and the re-encryption mixnets. In this paper we analyze four types of mixnets, of which one decryption and three re-encryption types. They were implemented in the Java programing language and evaluated on several criterias as: the number of messages, the total number of nodes, the number of threshold nodes, and the key length of underlying crypto system. In the results section we compare the results from the practical tests to answer the research question, which type of mixnets has better features.

Abstract. This paper introduces PandA, a software framework for Pairings and Arithmetic. It is designed to bring together advances in the efficient computation of cryptographic pairings and the development and implementation of pairing-based protocols. The intention behind the PandA framework is to give protocol designers and implementors easy access to a toolbox of all functions needed for implementing pairing-based cryptographic protocols, while making it possible to use state-of-the-art algorithms for pairing computation and group arithmetic. PandA offers an API in the C programming language and all arithmetic operations run in constant time to protect against timing attacks. The framework also makes it easy to consistently test and benchmark the lower level functions used in pairing-based protocols. As an example of how easy it is to implement pairing-based protocols with PandA, we use BonehLynn-Shacham (BLS) signatures. Our PandA-based implementation of BLS needs only 434640 cycles for signature generation and 5832584 cycles for signature verification on one core of an Intel i5-3210M CPU. This includes full protection against timing attacks and compression of public keys and signatures.

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