Myung-Hwan Kim

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We propose a new broadcast encryption scheme based on the idea of 'one key per each punctured interval'. Let r be the number of revoked users. In our scheme with p-punctured c-intervals, the transmission overhead is roughly r p+1 as r grows. Our scheme is very flexible with two parameters p and c. We may take p as large as possible if a user device allows a(More)
OBJECTIVE Autoimmune pancreatitis (AIP) is a treatable form of chronic pancreatitis that has been increasingly recognised over the last decade. We set out to better understand the current burden of AIP at several academic institutions diagnosed using the International Consensus Diagnostic Criteria, and to describe long-term outcomes, including organs(More)
We develop a couple of new methods to reduce transmission overheads in broadcast encryption. The methods are based on the idea of assigning one key per each partition using one-way key chains after partitioning the users. One method adopts skipping chains on partitions containing up to p revoked users and the other adopts cascade chains on partitions with(More)
Because acute cholangitis sometimes rapidly progresses to a severe form accompanied by organ dysfunction, caused by the systemic inflammatory response syndrome (SIRS) and/or sepsis, prompt diagnosis and severity assessment are necessary for appropriate management, including intensive care with organ support and urgent biliary drainage in addition to medical(More)
At PKC 2003 Paeng, Jung, and Ha proposed a lattice based public key cryptosystem(PJH). It is originated from GGH, and designed as a hybrid of GGH and NTRUEncrypt in order to reduce the key size. They claimed that PJH is secure against all possible attacks, especially against lattice attacks. However, in this paper, we present a key recovery attack, based on(More)
Since broadcast encryption was first introduced in 1993 by Fiat and Naor, many broadcast encryption schemes have been developed. Among these, schemes based on tree structure and linear structure are notable. The subset difference (SD) scheme and layered subset difference (LSD) scheme based on tree structure have small user-key size and small transmission(More)
The author hereby grants to MIT permission to reproduce and to distribute publicity paper and electronic copies of this thesis document in whole or in part in any medium now known and hereafter created. Abstract In this thesis, we show that single-petaled K-types and quasi-single-petaled K-types for reductive Lie groups generalize petite K-types for split(More)