针对印刷过程中印刷电路很容易产生短路、断路、毛刺等缺陷问题,提出一种基于ORB(oriented FAST and rotated Brief)算法的印刷电路检测方法。首先,针对原始ORB特征匹配算法出现大量误匹配的问题,提出了一种基于空间距离的提纯法对匹配对进行提纯;其次,利用提纯后的匹配点计算待测图像和模板图像的仿射变换矩阵;再次,利用图像差分检测法对印刷电子屏印刷电路检测。结果表明:该算法在速度与精度方面均有提高。
（k, n） halftone visual cryptography （HVC） is proposed based on Shamir＇ s secret sharing （HVCSSS）, and through this method a binary secret image can be hided into n halftone images, and the secret image can be revealed from any k halftone images. Firstly, using Shamir＇ s secret sharing, a binary secret image can be shared into n meaningless shares; secondly, hiding n shares into n halftone images through self-hiding method; and then n extracted shares can be obtained from n halftone images through self-decrypt method; finally, picking any k shares from n extracted shares, the secret image can be revealed by using Lagrange interpolation. The main contribution is that applying Shamir＇ s secret sharing to realize a （k, n） HVC, and this method neither requires code book nor suffers from pixel expansion. Experimental results show HVCSSS can realize a （k, n） HVC in gray-scale and color halftone images, and correct decoding rate （CDR） of revealed secret image can be guaranteed.
后量子时代,基于格理论的公钥密码被认为是最有前途的抵抗量子计算机攻击的公钥密码体制.然而,相对于格上公钥加密体制和数字签名方案的快速发展,基于格上困难问题的密钥协商协议成果却较少.因此,现阶段如何构建格上安全的密钥协商协议是密码学领域具有挑战性的问题之一.针对上述问题,基于环上带错误学习问题困难假设,采用调和技术构造了一种新的认证密钥协商协议RAKA(authenticated key agreement protocol based on reconciliation technique),该方案采用格上陷门函数技术提供了单向认证功能,并且在Ring-LWE假设下证明是安全的.与现有的基于LWE的密钥协商协议相比,该方案的共享会话密钥减小为2nlog q,效率更高;同时,由于该方案的安全性是基于格上困难问题,因此可以抵抗量子攻击.
