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Mathematical Problems in Engineering
Volume 2012, Article ID 402890, 14 pages
Research Article

Re-Encryption Method Designed by Row Complete Matrix

1Kaohsiung Medical University, Kaohsiung 80708, Taiwan
2Kun Shan University, Yung-Kang 71003, Taiwan
3National Chengchi University, Taipei 11605, Taiwan

Received 20 January 2012; Revised 30 March 2012; Accepted 30 March 2012

Academic Editor: Zheng-Guang Wu

Copyright © 2012 I-Te Chen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


With the prevalence of Internet access, document storage has become a fundamental web service in recent years. One important topic is how to design a secure channel for efficiently sharing documents with another receiver. In this paper, we demonstrate a re-encryption method that is designed with row complete matrices. With this new method, the document owner can share a ciphertext in the cloud with another receiver by sending a serial number to the server and giving the receiver a corresponding key at the same time. This method ensures that the server cannot obtain the information about key and plaintext and that the receiver cannot obtain the original key of the owner either. Only the owner has the knowledge of all the information. Using this re-encryption system, the cloud server can provide a secure file-sharing service without worrying about the shared key management problem. Moreover, the cost of re-encryption will not increase even when the encryption is strengthened with longer encryption keys.