基於視覺密碼之彩色機密隱藏機制

Abstract

傳統的加密法需要大量且複雜的運算才能將秘密訊息予以解密，然而視覺密碼學有別於其他加密機制，其利用秘密分享的概念，將秘密訊息藏至數張分享影像內，解密的動作不需要透過電腦的計算輔助，只需將數張分享影像利用人工加以疊合，藉由人眼便可解讀出機密訊息，在安全性方面，任何一方都無法從任何一張分享影像中解讀出隱藏的機密訊息。目前已有許多研究是透過產生不具意義的亂碼分享影像來確保分享影像不會洩露機密影像的資訊，而本研究透過半色調技術將視覺密碼隱藏在兩張具有意義的分享影像上，有意義的分享影像將不會造成有心人士的猜疑，不僅保有視覺密碼的特性，且亦可應用於複雜度高的彩色影像。Visual cryptography is different from traditional cryptography. Neither time-consuming computation nor complex cryptographic knowledge is needed. Stacking is the only operation required to recover a secret image. Note that the individual image does not give the hackers any information about the secret image. Most researches tried to deal with non-meaningful color share images. Hence, we propose a color secret hiding method based on visual cryptography for hiding a color image in two meaningful color share images in this paper. The color decomposition approach and halftone technology are applied to cope with secret color images. Then the concept of the human visual system is utilized to generate two color meaningful share images.