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# 数学代写|密码学代写Cryptography Theory代考|CP3409 Introduction to Cryptography

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## 数学代写|密码学Cryptography Theory代考|Introduction to Cryptography

Cryptography, from the Greek meaning “secret writing,” is the science of making messages unintelligible to all except those for whom the messages are intended. In this way, sensitive or private messages are kept secure and protected from unauthorized or unwanted access by persons or entities other than the intended recipients.
The message intended to be sent is the plaintext. An example of plaintext is
Eyes of the World.
The communications are kept secure by converting the plaintext into ciphertext by a process called encryption. Encryption is achieved through the use of an encryption transformation. An example of an encryption transformation is
$e=$ replace each letter of the plaintext with the letter that is $k$ places to the right in the alphabet, where $k$ is an integer that satisfies $k \in{0,1,2, \ldots, 25}$.
(Note: in the encryption transformation $e$, the alphabet wraps around, and thus, if $k=2$, then the letter $\mathrm{y}$ is replaced with $\mathrm{a}, \mathrm{z}$ is replaced with $\mathrm{b}$, and so on.)

The person sending the plaintext can only encrypt if she has chosen a value for $k$, which is the “key” to encryption. Generally, an encryption key is the additional information required so that plaintext can be converted to ciphertext using an encryption transformation. Given an encryption transformation, the set of all possible encryption keys is the encryption keyspace. For the encryption transformation $e$ given above, the keyspace is ${0,1,2, \ldots, 25}$.

## 数学代写|密码学Cryptography Theory代考|The Players in the Game

We introduce some formal notation for a cryptosystem. We assume the person sending plaintext message $M$ is “Alice,” denoted by $A$, and the intended recipient is “Bob,” denoted by $B$. Let $e$ denote an encryption transformation and let $k_e$ be an encryption key. Let $d$ denote the corresponding decryption transformation with decryption key $k_d$. Let
$$C=e\left(M, k_e\right)$$
denote the encryption of $M$ into ciphertext $C$ using transformation $e$ and key $k_e$. Then
$$M=d\left(C, k_d\right)=d\left(e\left(M, k_e\right), k_d\right)$$
denotes the decryption of $C$ back to $M$. In the example of Section 1.1,
$$M=\text { Eyes of the World, }$$
$e=$ replace each letter of the plaintext with the letter that is $k$ places to the right in the alphabet where $k \in{0,1,2, \ldots, 25}$,
$$k_e=2,$$
and
$C=$ Gagu qh vjg Yqtnf
Thus in formal notation, the encryption-decryption process in Figure $1.1$ can be written as
Gagu qh vjg Yqtnf $=e($ Eyes of the World, 2),
Eyes of the World $=d($ Gagu qh vjg Yqtnf, 2).

## 数学代写|密码学Cryptography Theory代考|Introduction to Cryptography

Eyes of the World。通过一种称为加密的过程将明文转换为密文来保证通信的安全。加密是通过使用加密转换实现的。加密转换的一个例子是
$e=$用字母$k$替换明文中的每一个字母，其中$k$是一个满足$k \in{0,1,2, \ldots, 25}$的整数。
(注意:在加密转换$e$中，字母绕着走，因此，如果$k=2$，则字母$\mathrm{y}$被替换为$\mathrm{a}, \mathrm{z}$被替换为$\mathrm{b}$，以此类推。

## 数学代写|密码学密码学 理论代考|游戏中的玩家

$$C=e\left(M, k_e\right)$$

$$M=d\left(C, k_d\right)=d\left(e\left(M, k_e\right), k_d\right)$$

$$M=\text { Eyes of the World, }$$
$e=$将明文中的每个字母替换为字母$k$，其中$k \in{0,1,2, \ldots, 25}$，
$$k_e=2,$$

$C=$ Gagu qh vjg Yqtnf

Gagu qh vjg Yqtnf $=e($世界之目，2)，

## 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。