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In 1996, the concept of proxy signature was introduced by Mambo, Usuda and Okamoto in M. Mambo et al. (1996). A strong proxy signature scheme has been introduced in B. Lee et al. (2001), which we call LKK (B. Lee, H. Kim, K. Kim) scheme. In Z. Dong et al. (2003), the authors showed that the LKK scheme is vulnerable to their attack. In this paper, based on the vulnerability of the LKK scheme and blind Schnorr signature scheme, we propose a revised proxy signature and a proxy blind signature scheme. The basic idea is to propose the revised scheme resisting their attack and to make it difficult for the original signer to delete a delegation value.

These days in Internet, emerging various applications has become more complicated and needed large bandwidth under the necessity to securely use them. Network bandwidth has increased as much as to support those needs. But it becomes increasingly difficult to utilize them to their full capacity [I]. In other word, up-grading of network bandwidth is not enough solution to enhance performance experienced by end users. There are so many causes including TCP/IP protocol behaviors, application issues and network configuration issues etc. In this paper, I would suggest a new system diagnosis tool to settle specially enhancement of end user & E2E performance. The goals of this tool are to enable an end user & network operator to diagnose an end-host system and E2E performance weak point, offer some advises and optimize the systems by given auto or manual system metrics tuning guideline. And I wish to get an overlay network to understand network characteristics and utilize full network capacity. In this paper, we look over briefly other relative projects and introduce some key metrics to optimize end-host performance