Efficient Authenticated Encryption Schemes with Public Verifiability

An authenticated encryption scheme allows messages to be encrypted and authenticated simultaneously. In 2003, Ma and Chen proposed such a scheme with public verifiability. That is, in their scheme the receiver can efficiently prove to a third party that a message is indeed originated from a specific sender. In this paper, we first identify two security weaknesses in the Ma-Chen authenticated encryption scheme. Then, based on the Schnorr signature, we proposed an efficient and secure improved scheme such that all the desired security requirements are satisfied.Comment: Early version appears in the Proc. of The 60th IEEE Vehicular Technology Conference (VTC 2004-Fall) - Wireless Technologies for Global Security. IEEE, 200

Combining message encryption and authentication

The first part of the paper explains the need for combining message encryption and authentication. We begin with the example to emphasize the fact that privacy‡ does not imply authenticity. Then we prove, one needs both privacy and authenticity, even if one's aim is just getting privacy. In the second part we present an overview of different methods for providing authenticated encryption (AE) i.e. generic compositions, single-pass modes and two-pass combined modes. We analyze what are the advantages and disadvantages of different AE constructions. In the third part of the paper we focus on nonce§ based authenticated encryption modes. Our motivation is the wish to know the methodology of designing authenticated encryption mode of operation. We take into consideration a few most important properties, e.g. parallelizability, memory requirements and pre-processing capability. We analyze possibilities of choice of underlying encryption and authentication components and their order in a message we also try to answer. What does single-key mode really mean? Finally we mention the importance of provable security theory in the security of authenticated encryption modes

Building Secure and Anonymous Communication Channel: Formal Model and its Prototype Implementation

Various techniques need to be combined to realize anonymously authenticated communication. Cryptographic tools enable anonymous user authentication while anonymous communication protocols hide users' IP addresses from service providers. One simple approach for realizing anonymously authenticated communication is their simple combination, but this gives rise to another issue; how to build a secure channel. The current public key infrastructure cannot be used since the user's public key identifies the user. To cope with this issue, we propose a protocol that uses identity-based encryption for packet encryption without sacrificing anonymity, and group signature for anonymous user authentication. Communications in the protocol take place through proxy entities that conceal users' IP addresses from service providers. The underlying group signature is customized to meet our objective and improve its efficiency. We also introduce a proof-of-concept implementation to demonstrate the protocol's feasibility. We compare its performance to SSL communication and demonstrate its practicality, and conclude that the protocol realizes secure, anonymous, and authenticated communication between users and service providers with practical performance.Comment: This is a preprint version of our paper presented in SAC'14, March 24-28, 2014, Gyeongju, Korea. ACMSAC 201

Customizable Sponge-Based Authenticated Encryption Using 16-bit S-boxes

Authenticated encryption (AE) is a symmetric key cryptographic scheme that aims to provide both confidentiality and data integrity. There are many AE algorithms in existence today. However, they are often far from ideal in terms of efficiency and ease of use. For this reason, there is ongoing effort to develop new AE algorithms that are secure, efficient, and easy to use. The sponge construction is a relatively new cryptographic primitive that has gained popularity since the sponge-based K ECCAK algorithm won the SHA-3 hashing competition. The duplex construction, which is closely related to the sponge, pro- vides promising potential for secure and efficient authenticated encryption. In this paper we introduce a novel authenticated encryption algorithm based on the duplex construction that is targeted for hardware implementation. We provide explicit customization guidelines for users who desire unique authenticated encryption solutions within our security margins. Our substitution step uses 16 × 16 AES-like S-boxes which are novel because they are the largest bijective S-boxes to be used by an encryption scheme in the literature and are still efficiently implementable in both hardware and software

Real-time encryption and authentication of medical video streams on FPGA

This work presents an FPGA-based solution for the encryption and authentication of video streams of surgeries. The most important is minimal latency. To achieve this, a block cipher with an authenticated mode of operation is used. We choose to use AES128 with Galois/Counter Mode (GCM), because the this mode of operation is patent-free and it allows for random read access. This solution minimizes the overhead on the existing critical path to a single XOR operation. Our solution supports the broadcasting of the video stream. When a new receiver announces itself, it should receive the active keys of the sender. Therefore, a key transport protocol is used to establish a key between the sender and the announcing receiver. A proof-of-concept implementation of the proposed solution has been implemented and tested. While the complete video stream is encrypted and authenticated, the demonstrator confirms that the added latency, which is around 23 s, could not be noticed by the human eye. Random read access and the key establishment protocol provide a flexible solution

Revisiting Deniability in Quantum Key Exchange via Covert Communication and Entanglement Distillation

We revisit the notion of deniability in quantum key exchange (QKE), a topic that remains largely unexplored. In the only work on this subject by Donald Beaver, it is argued that QKE is not necessarily deniable due to an eavesdropping attack that limits key equivocation. We provide more insight into the nature of this attack and how it extends to other constructions such as QKE obtained from uncloneable encryption. We then adopt the framework for quantum authenticated key exchange, developed by Mosca et al., and extend it to introduce the notion of coercer-deniable QKE, formalized in terms of the indistinguishability of real and fake coercer views. Next, we apply results from a recent work by Arrazola and Scarani on covert quantum communication to establish a connection between covert QKE and deniability. We propose DC-QKE, a simple deniable covert QKE protocol, and prove its deniability via a reduction to the security of covert QKE. Finally, we consider how entanglement distillation can be used to enable information-theoretically deniable protocols for QKE and tasks beyond key exchange.Comment: 16 pages, published in the proceedings of NordSec 201