传统的视觉密码方案是通过直接叠加分享份来恢复秘密图像的,这种解密方式实质上是对分享份进行逻辑或运算, 白像素无法完全恢复,解密效果不理想. 利用异或运算的自反性改进加密方式,并使用与数字图像相同的颜色表示方式,提出一种基于异或解密的(k,n)随机网格视觉密码方案.该方案有两种解密方式: 当没有计算设备时, 使用传统的叠加解密,解密过程简单; 当有计算设备时, 使用异或解密, 需少量计算,但具有更好的视觉质量, 并且当所有分享份都参与异或解密时,可以无损恢复秘密图像. 与已有的视觉密码方案相比,该方案提高了解密图像的视觉质量.

Traditional visual cryptography schemes recover secret images by stacking shares directly. Since the stacking operation can be denoted by logical OR operation and since white pixels can't be fully recovered with these schemes, the decryption effect is not satisfactory. This paper proposes a (k,n) random grid-based visual cryptography scheme based on exclusive OR (XOR) decryption by using reflexivity of XOR for encryption and by applying the same color representation method as digital images. The secret images can be recovered in two situations: when computational devices are not available, the secret images can be recovered by stacking shares directly; when computational devices are available, the secret images can be recovered by XOR operation. With better visual quality, the secret images recovered this way can be lossless since all shares are collected. Compared with existing visual cryptography schemes, better visual quality is obtained with this new scheme.