### 数学代写|密码学作业代写Cryptography & Cryptanalysis代考|Brief History of Visual Cryptography

statistics-lab™ 为您的留学生涯保驾护航 在代写密码学Cryptography & Cryptanalysis方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写密码学Cryptography & Cryptanalysis代写方面经验极为丰富，各种代写密码学Cryptography & Cryptanalysis相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

## 数学代写|密码学作业代写Cryptography & Cryptanalysis代考|Online Transaction Security

Nowadays, online transaction is one of the major transaction methods due to the widely use of e-commerce. Such transactions include online banking, online payment on an e-commerce platform, payment by scanning a $Q R$ code using a payment App, and payment using an online social network App. For these transactions to be secure, one must ensure that both the hardware and the software are secure so that there are no Trojan horses residing in it. A Trojan horse is a malicious program, in hardware or in software, residing in a client or a sever, trying to compromise the security of a computer system or a communication system.

However, considering the diverse sources of Apps and softwares installed on a computer or cellphone, one cannot guarantee that his/her device is Trojan-free. Using such insecure devices, how to ensure that the transaction is safe? A Trojan horse may

monitor all messages from bank sever to a user’s device and may be able to modify these messages. There are two common attacks on the communication between the bank sever and the client computer, as illustrate in Fig. 1.1. In Fig. 1.1a, an honest user Alice uses her computer to send a message to the bank sever, asking it to transfer $100 \$$to Bob. But this message is intercepted by a Trojan horse residing in her computer. Here we denote the Trojan horse as Tom. Trojan horse modified Alice’s message to be ‘Transfer 100 \$$ to Tom’. In a second scenario, as shown in Fig. 1.1b, the Trojan horse Tom pretends to be Alice, and sends a message to bank sever, asking it to transfer 100 from Alice’s account to Tom’s account. The first scenario asks for message authentication to ensure that the messages between the sever and the client are not modified. The second scenario asks for person identification, so that the sever can ensure that it is talking to the right person. Visual cryptography provides solutions to combating these attacks, thus can ensure that we can make online transactions on an insecure device, such as computer, smart phone, smart card terminal, etc. This protocol was first proposed by Naor and Finkas [34] and was further developed by Borchert and Reinhardt in [6], and by Pape in [37]. We briefly outline their solutions to authentication and identification in the following steps. 1. Before the transaction starts, the bank sever generates a random grid (random black/white dots) as the first share, which is then printed on a transparency, and distributed to Alice. Alternatively, the random grid image can be sent to Alice in a secure email, and Alice can print it out on a transparency. Such a transparency can be seen in Fig. 1.2a. ## 数学代写|密码学作业代写Cryptography & Cryptanalysis代考|Privacy Protection Another application of VC is privacy protection. Personal privacy, such as biometric data (fingerprint, face template, finger vein, iris, etc.), medical information and personal financial information, contains sensitive personal information that should be owned only to the owner himself/herself. The issue here is that, these information is also important to access control and disease diagnosis. So, privacy protection addresses the ways to protect personal privacy without hindering legitimate usage of these information. Visual cryptography provides solutions to privacy protection in several scenarios. This subsection reviews some applications in privacy protection for biometric data and medical data$[1,2,4,39,56]$. The biometric feature is unique and cannot be easily changed during life time. So, unlike password, once it is leaked, one cannot come up with another one. But face and fingerprint are used so common today, such as paying by face scanning. For these applications, there are two steps involved: the enrollment step and the authentication step. During the enrollment step, the biometric data is recorded and the features are extracted. These features, usually referred to as template, are stored in a database. During authentication, such as entrance control by fingerprint recognition, a live fingerprint is taken from the visitor and the biometric features are extracted. These live features are then compared with the template stored in the database. The biometric templates are usually stored in a central database owned by a company [39]. Any successful attack to these databases may lead to leakage of user’s privacy. Ross and Othman proposed to use$\mathrm{VC}$to split a biometric image into two shares to protect privacy. For example, for fingerprint recognition, this idea is shown in Fig. 1.3. During enrollment step, the fingerprint image is split into two meaningless shares by VC encoding algorithm. Each share contains totally random patterns and is stored in a separate database. Even if one of the database is attacked, only one share is leaked to the attacker. However, from only one share, it is not possible to gain any information about the fingerprint. During authentication process, such as person verification, the two fingerprint shares are loaded from the two databases. After VC decoding, one may reconstruct the fingerprint enrolled, i.e., the template. Then this template is matched to a live fingerprint. Using such a system, the privacy of the fingerprint is ensured even though one of the database is not secure. In general, for$(k, n)$-threshold$\mathrm{VC}$, this system may resist successful attacks to up to$k-1$databases. Similar system can also be used in securing medical or health care data$[4,56]$. Yang et al. considered the scenarin that two or more hnspitals need to share their medical images, such as CT (computed tomography), X-ray, etc. But sharing these images between two private systems directly is usually difficult. On the other side, uploading all images to a public system is insecure. Yang et al. proposed to use a random grid type algorithm to generate the two shares of the medical image. Referring to Fig. 1.4, hospital 1 has a medical equipment. After the medical equipment generates the medical image, it uses a random key$K$to generate the the first share image, the master share. Using master share and the medical image, the VC encoding algorithm can generate the second share, which is called the key share. The master share is not totally random, but is generated by a pseudo random number generator. Anyone having the key$K$can generate the master share. The Master share, or the key$K$, is stored in private database 1 in hospital 1. The key share is uploaded to public system. Thus, leakage of key share from the public system won’t lead to lose of private information. When another hospital, hospital 2, needs to access the medical image, and after authentication, the key share is sent to private system in hospital 2 . The key$K$, which is significantly shorter than the master share, is also sent to the private system 2 . Using this key, private system 2 can generate the master share. Finally, private system 2 is able to stack the two shares to recover the medical image. This system has two advantageous features. First, the medical image is secure to information leakage from the public database. Second, only the key that is used to generate the master share needs to be sent, which is fast and efficient. ## 数学代写|密码学作业代写Cryptography & Cryptanalysis代考|Barcode Security QR code is widely used for online and offline payment, especially in China and other east Asian countries. A QR code is a two-dimensional bar code, which can store numbers, URL, or even text. In [17], Fang designed a VC scheme to share a QR code. The QR code image is used as the secret image to VC encoder. The two shares contain random binary pattern, but the function patterns are reserved. By scanning one share, the scanning App cannot find anything and reports a decoding failure. But after stacking the shares, the contents of the QR code can be decoded by a standard QR decoder. Similar ideas are also used in$[11,14]$. A secret QR code is split into several share QR codes. Each share$Q R$code is a legitimate one. So each$Q R$code can be scanned and decoded. The decoded message is irrelevant to the secret message. Once we stack all the shares, we get another QR code image. Scanning this QR image, we may decode the secret message. The advantage of Chow’s and Cheng’s scheme over Fang’s is the cover$\overline{Q R}$codes. which behave like normal$\overline{\mathrm{QR}}$code. as illustrated in Fig. 1.5. ## 密码学代写 ## 数学代写|密码学作业代写Cryptography & Cryptanalysis代考|Online Transaction Security 如今，由于电子商务的广泛应用，网上交易成为主要的交易方式之一。此类交易包括网上银行、电子商务平台上的在线支付、扫描支付问R使用支付应用程序的代码，以及使用在线社交网络应用程序的支付。为了使这些交易安全，必须确保硬件和软件都是安全的，这样其中就没有特洛伊木马。特洛伊木马是一种恶意程序，存在于硬件或软件中，驻留在客户端或服务器中，试图破坏计算机系统或通信系统的安全性。 但是，考虑到计算机或手机上安装的应用程序和软件的来源多种多样，不能保证他/她的设备没有木马。使用这种不安全的设备，如何保证交易安全？特洛伊木马可能 监控从银行服务器到用户设备的所有消息，并且可能能够修改这些消息。银行服务器与客户端计算机之间的通信有两种常见的攻击方式，如图 1.1 所示。在图 1.1a 中，诚实用户 Alice 使用她的计算机向银行服务器发送一条消息，要求它进行转账100$给鲍勃。但这条消息被她电脑中的特洛伊木马截获。在这里，我们将特洛伊木马表示为 Tom。特洛伊木马将 Alice 的消息修改为“Transfer”100\$给汤姆’。在第二种情况下，如图 1.1b 所示，特洛伊木马 Tom 伪装成 Alice，并向银行服务器发送一条消息，要求它从 Alice 的账户向 Tom 的账户转账 100。第一个场景要求进行消息认证，以确保服务器和客户端之间的消息不被修改。第二种情况要求进行人员识别，以便服务器可以确保它正在与正确的人交谈。

1. 在交易开始之前，银行服务器会生成一个随机网格（随机黑/白点）作为第一个份额，然后将其打印在透明胶片上，然后分发给 Alice。或者，随机网格图像可以通过安全电子邮件发送给 Alice，Alice 可以将其打印在透明胶片上。这种透明度可以在图 1.2a 中看到。

## 数学代写|密码学作业代写Cryptography & Cryptanalysis代考|Privacy Protection

VC 的另一个应用是隐私保护。个人隐私，例如生物特征数据（指纹、面部模板、手指静脉、虹膜等）、医疗信息和个人财务信息，包含敏感的个人信息，本应只属于所有者本人。这里的问题是，这些信息对于访问控制和疾病诊断也很重要。因此，隐私保护解决了在不妨碍这些信息的合法使用的情况下保护个人隐私的方法。

## 有限元方法代写

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## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。