Mitsuo Okada

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We propose and evaluate a privacy-secure image trading framework using blind fingerprinting technique which embeds a user ID using watermark technique. The framework provides a privacy-secure trading even though there is no confidential relation between a content provider and a user. In a conventional fingerprinting scheme, a content provider offers a user(More)
The most common CAPTCHA technique, Gimpy which requires a user to type in twisted characters has following problems. Characters are over twisted because some spammer uses OCR to bypass verification. Type in operation on mobile and tablet devices is difficult where keyboard are not utilized. Our method uses multiple noise images where invisible objects or(More)
—A privacy-secure content trading system based on semi-blind fingerprinting is presented. Semi-blind fingerprinting provides privacy-secure content trading as secure as blind fingerprinting at feasible processing cost with sufficient robustness. This system assures a fair trading for both a content provider and a purchaser which is effective for a market(More)
A user-friendly digital watermark extraction method is proposed in this paper. Watermark in analog paper such as paper currency can be extracted by simply transmitting the light through the paper. On the other hand, most existing digital watermarking methods require an extraction program. However, ordinary people cannot verify the validity of an extraction(More)
—A privacy-secure content trading system based on semi-blind fingerprinting which provides privacy-secure content trading as secure as blind fingerprinting at feasible processing cost with sufficient robustness is evaluated in this paper. This system assures both a content provider and a purchaser of a fair trading which is effective in a market where(More)
In recent years, web services have become a new application over the open, complex internet. In that, web services security issues have become more and more important. But, there is no effective access control method to assure the web service security. This paper proposes a simple and effective formalization of concepts that have to be supported for(More)
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