目的为了解决当前混沌图像加密技术忽略了随机序列产生的时间延迟现象,且难以克服其自身迭代的周期性,使其序列的自相关性不理想,导致密文安全性不佳等问题。方法引入级联耦合混沌半导体环形激光器,设计基于物理随机位生成器与混沌像素...目的为了解决当前混沌图像加密技术忽略了随机序列产生的时间延迟现象,且难以克服其自身迭代的周期性,使其序列的自相关性不理想,导致密文安全性不佳等问题。方法引入级联耦合混沌半导体环形激光器,设计基于物理随机位生成器与混沌像素交叉互换的图像加密算法。首先引入SHA-256散列函数,利用明文像素值,生成一个256位的密钥,并将其分割为一系列的8位子密钥;利用这些子密钥来计算Logistic-Sine复合映射的初始条件,以输出一组随机序列;根据混沌序列,定义像素交叉互换机制,对输入明文进行预处理,消除相邻像素之间的相关性;基于级联耦合混沌半导体环形激光器,充分利用其自身的时间延迟与交叉反馈的特性,设计物理随机位生成器,以同步输出考虑时间延迟的控制矩阵与随机位流;将Logistic-Sine复合映射输出的混沌序列转换为一个过渡矩阵,联合控制矩阵,定义像素混淆机制,彻底改变明文的像素位置;最后,利用随机位流,设计像素联系扩散函数,改变图像的像素值。结果实验结果显示,与当前混沌加密技术相比,所提算法具有更高的安全性与鲁棒性,能够有效抗击明文攻击,相应的密文熵值约为7.9958,且NPCR(7)Number of Pixel Change Rate(8)、UACI(Unified Average Changing Intensity)分别为99.50%、33.46%。结论所提加密算法具有较高的安全性和抗攻击能力,能够安全保护图像在网络中传输,在信息防伪等领域具有较好的应用价值。展开更多
Although the Japan Society of Obstetrics and Gynecology (JSOG) endorses new-type PGD using CGH for only carriers of balanced chromosomal translocations, it is against the ethical guidelines of the JSOG to decide whe...Although the Japan Society of Obstetrics and Gynecology (JSOG) endorses new-type PGD using CGH for only carriers of balanced chromosomal translocations, it is against the ethical guidelines of the JSOG to decide whether or not embryos should be implanted due to aneuploidy discovered as a result of new-type PGD. In the author's opinion, it should be at the discretion of the JSOG's own randomized controlled trials, which should involve multiple facilities, whether or not a scientific basis can be found for the value of the new-type PGD in cases of recurrent miscarriage, in cases of implantation failure, and in cases where the women are of advanced maternal age. Dr. Netsu's 36 cases of selective reduction may be against the Japanese Maternal Health Protection Law that prohibits abortion due to congenital disease, but with the backdrop that there are many abortions that are performed as a result of parental convenience in Japan, it is difficult to understand the difference between the over 300,000 abortions that are performed every year in Japan and Dr. Netsu's prescribed surgery which is designed to selectively reduce fetuses with congenital disease for the purpose of evading physical danger for women with multiple gestations.展开更多
文摘目的为了解决当前混沌图像加密技术忽略了随机序列产生的时间延迟现象,且难以克服其自身迭代的周期性,使其序列的自相关性不理想,导致密文安全性不佳等问题。方法引入级联耦合混沌半导体环形激光器,设计基于物理随机位生成器与混沌像素交叉互换的图像加密算法。首先引入SHA-256散列函数,利用明文像素值,生成一个256位的密钥,并将其分割为一系列的8位子密钥;利用这些子密钥来计算Logistic-Sine复合映射的初始条件,以输出一组随机序列;根据混沌序列,定义像素交叉互换机制,对输入明文进行预处理,消除相邻像素之间的相关性;基于级联耦合混沌半导体环形激光器,充分利用其自身的时间延迟与交叉反馈的特性,设计物理随机位生成器,以同步输出考虑时间延迟的控制矩阵与随机位流;将Logistic-Sine复合映射输出的混沌序列转换为一个过渡矩阵,联合控制矩阵,定义像素混淆机制,彻底改变明文的像素位置;最后,利用随机位流,设计像素联系扩散函数,改变图像的像素值。结果实验结果显示,与当前混沌加密技术相比,所提算法具有更高的安全性与鲁棒性,能够有效抗击明文攻击,相应的密文熵值约为7.9958,且NPCR(7)Number of Pixel Change Rate(8)、UACI(Unified Average Changing Intensity)分别为99.50%、33.46%。结论所提加密算法具有较高的安全性和抗攻击能力,能够安全保护图像在网络中传输,在信息防伪等领域具有较好的应用价值。
文摘Although the Japan Society of Obstetrics and Gynecology (JSOG) endorses new-type PGD using CGH for only carriers of balanced chromosomal translocations, it is against the ethical guidelines of the JSOG to decide whether or not embryos should be implanted due to aneuploidy discovered as a result of new-type PGD. In the author's opinion, it should be at the discretion of the JSOG's own randomized controlled trials, which should involve multiple facilities, whether or not a scientific basis can be found for the value of the new-type PGD in cases of recurrent miscarriage, in cases of implantation failure, and in cases where the women are of advanced maternal age. Dr. Netsu's 36 cases of selective reduction may be against the Japanese Maternal Health Protection Law that prohibits abortion due to congenital disease, but with the backdrop that there are many abortions that are performed as a result of parental convenience in Japan, it is difficult to understand the difference between the over 300,000 abortions that are performed every year in Japan and Dr. Netsu's prescribed surgery which is designed to selectively reduce fetuses with congenital disease for the purpose of evading physical danger for women with multiple gestations.