【摘要】 Ｍ．Ｎａｏｒ和Ａ．Ｓｈａｍｉｒ于１９９４年提出了一种新的密钥分享方案，即可视密码术（ＶｉｓｕａｌＣｒｙｐｔｏｇｒａｐｈｙ）．本文将此密码技术改进为叠像术，用有意义的明文图像代替原来的随机噪声图象，使之更具安全性．更多还原

【Abstract】 A new secret sharing scheme, visual cryptography, was proposed by Moni Naor and Adi Shamir in 1994.We present a new shceme named image covering, in which the subkey image with random noise is replaced by meaningful text image.更多还原