Showing papers by "Hyoung Joong Kim published in 2013"

Secure Mobile Credit Card Payment Protocol based on Certificateless Signcryption

Abstract: The increase of the smartphone users has popularized the mobile payment and the mobile credit card users are rapidly getting increased. The mobile credit cards that currently used provide its users with the service through downloading mobile credit card information into USIM. The mobile credit card saved in USIM has the minimized information for the security and is based on PKI. However certificate-based payment system has a complicated procedure and costs a lot of money to manage the certificates and CRL(Certificate Revocation List). Furthermore, It can be a obstacle to develop local e-commerce in Korea because it is hard for foreigners to use them. We propose the secure and efficient mobile credit card payment protocol based on certificateless signcryption which solve the problem of certificate use.

Compressing JPEG compressed image using reversible data hiding technique

Abstract: Since the concept of reversible data hiding technique was introduced, many researchers have applied it for authentication of uncompressed images. In this paper, an algorithm is introduced to compress JPEG files again without any loss in image quality. The proposed method can modify an entire segment of VLC codeword sequence to embed a bit of data. The modified codewords may destroy the correlation, or the smoothness, between neighboring pixels of the recovered image. The data extractor utilizes the smoothness change to know the hidden data. For this, a novel smoothness measurement function which uses both inter- and intra-MAD values is proposed. When the smoothness change is small, two consecutive segments are concatenated to extract correct data with higher smoothness sensitivity. As a result, compression ratio or embedding capacity is increased in most natural images.