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1

A Reliable Real-time Multicast Authentication Protocol with Provable Accuracy

Chang C. C., Cheng T. F.

Fundamenta Informaticae

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2014

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Vol. 131, nr 2

167--186

EN

With the rapid development of network technologies and the continuing growth of the online population, the distribution of streamed media on the Internet has become a cause for concern. In order to securely deliver large-scale message streams, various multicast authentication protocols have been proposed. Recently, Abdellatif et al. proposed a real-time multicast authentication protocol called LAR1. The LAR1 protocol has low computation and communication overheads and uses the erasure code function to deal with the packet loss problem. However, through careful analyses, we find that their scheme cannot resist impersonation attacks on signers and only partially solves the packet loss problem. Moreover, there are still some design weaknesses. Then, we propose a more secure multicast authentication protocol, called IMA, with almost the same computation overheads and lower communication overheads. We adopt the BAN logic to demonstrate the authentication accuracy of our proposed scheme. Comparisons of other related works show that our proposed IMA protocol maintains efficiency and is more secure. Therefore, our proposed protocol is more suitable for practical applications.

2

Data Compressor for VQ Index Tables

Lu T.-C., Chang C. C.

Fundamenta Informaticae

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2005

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Vol. 65, nr 4

353--371

EN

The vector quantization (VQ) compression scheme has been well accepted as an efficient image compression technique. However, the compression bit rate of the VQ scheme is limited. In order to improve its efficiency, in this paper, we shall propose a new lossless data compression scheme to further condense the VQ index table. The proposed scheme exploits the inter-block correlations in the index table to re-encode the indices. Unlike the well known existing re-encoding schemes such as SOC and STC, the proposed scheme uses a smaller number of compression codes to encode every index that coincides with another on the predefined path. Compared with VQ, SOC and STC, the proposed scheme performs better in terms of compression bit rate.

3

An Image Hiding Scheme Based on Multi-bit-reference Substitution Table Using Dynamic Programming Strategy

Chan C.-S., Chang C. C.

Fundamenta Informaticae

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2005

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Vol. 65, nr 4

291--305

EN

Simple least-significant-bit (LSB) substitution is the most straightforward way to embed the secret image in the host image. Based on the simple LSB substitution, the method using substitution table is proposed to improve the quality of the stego-image. In this paper, we shall bring up a new method that uses the un-embedded host pixel bits to partition the host pixel into different planes. This way, we can derive the optimal substitution table for each plane. By combining the optimal substitution tables, we can obtain the final result that we call the multi-bit-reference substitution table. After transforming the secret data according multi-bit-reference substitution table, we can embed the transformed secret data in the host image so that the host image will be degraded possibly less. The experimental results show that our method leads to good results.