基于状态参数的安全数码相机模型

A New Secure Digital Camera Model Based on State Parameter

现有安全数码相机不能识别二次获取图像且必须直接参与含水印数字照片的认证过程.针对上述问题,本文从含水印数字照片的密钥生成与传递方式入手,提出一种基于状态参数的新型安全数码相机模型.该模型通过设计相机密钥设置函数———级联-混沌映射,隐蔽地生成安全数码相机的相机密钥,然后以相机密钥和照片拍摄时相机的取景模式、焦距、拍摄时间等状态参数为明文数据,利用Hash函数计算出含水印数字照片的密钥,讨论分析了该模型中密钥的保密性和难伪造性,建立了相机与密钥的多对一非线性映射关系.实验结果表明,相机密钥或状态参数改变时,密钥的变化量近似均匀分布.

The current secure digital camera （SDC） model can not identify the secondary capture image and have to validate the integrity of watermarked images taken by it. To address these problems, a state parameter based SDC model is proposed by generating and transferring secret key which is used to produce a watermarked image. The cascade chaotic mapping is used to generate the camera key for the proposed SDC model. By the application of the plaintext data including camera key and state parameters in the image creation, such as viewfinder mode, focus, and time, the secret key is produced by Hash function. The confidentiality and anti-counterfeiting of secret key for the proposed SDC model were validated and one to many nonlinear mapping between the camera and the secret key was established. Experimental results demonstrate that the bit number variation of secret key follows approximately uniform distribution when the camera key or scene parameter is changed.