Yuji Suga

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Fast (k, n)-threshold secret sharing schemes with exclusive-OR operations have proposed by Kurihara et al. and Fujii et al. independently. Their method are ideal that share size is equal to the size of the data to be distributed with the benefits that can be handled very fast for using only XOR operation at distribution and restoration processes. In these(More)
Fast (k, n)-threshold secret sharing schemes with exclusive-OR operations have proposed by Kurihara et al. and Fujii et al. independently. Their method are ideal that share size is equal to the size of the data to be distributed with the benefits that can be handled very fast for using only XOR operation at distribution and restoration processes. In these(More)
In current content delivery service, contents are usually encrypted for access control mechanism, so several key distribution schemes have been proposed. In this paper, we propose a new key derivation scheme for hierarchy-based access control. We assume that content consumers are listed in digraph structure, and all nodes are assigned seeds(pre-keys) for(More)
A visual secret sharing scheme with an access structure based on a given graph has been proposed, and can be considered an extension of (2, n)-threshold visual secret sharing schemes. Ateniese et al. presented a decomposition method in which a dealer decomposes a given graph into star graphs, with qualified participants (vertices in a given graph) who have(More)
Fast (k, n)-threshold secret sharing schemes with exclusive-OR operations have proposed by Kurihara et al. And Fujii et al. Independently. Their method are ideal that share size is equal to the size of the data to be distributed with the benefits that can be handled very fast for using only XOR operation at distribution and restoration processes. Moreover(More)
This paper discusses forward secrecy functionality, which has come into the spotlight due to a series of news reports regarding the NSA. SSL/TLS server support for forward secrecy was introduced at major sites such as SNS at the end of last year, so servers enabling forward secrecy are increasing. This paper shows SSL/TLS servers status survey about(More)
In current content delivery cloud services, contents are usually encrypted for access control mechanism, so several key distribution/management schemes have been proposed. This paper proposes efficient key derivation schemes for the stream contents (or sequential contents) on cloud storage/delivery services, for example spreading video contents with time(More)