密码学的类型
“Cryptography is the standard of encrypting all the data and information by converting Plain text into cipher text for secure communication.”
“密码学是通过将纯文本转换为密文以进行安全通信来加密所有数据和信息的标准。”
Encryption is the key to secure all our data and information while we communicate with others over any transmission channel. Now, you might be thinking why this encryption matters a lot?
加密是在我们通过任何传输渠道与他人通信时保护我们所有数据和信息安全的关键。 现在，您可能在想为什么这种加密很重要？
Data is something that is important in each field. It may include your personal identity, your financial stats, your bank account details, or anything else. No one wants that their data should be accessed by any unauthorized user. But unfortunately, there are adversaries present in the market to snatch that information in a very smart way.
数据在每个领域都很重要。 它可能包括您的个人身份，您的财务统计数据，您的银行帐户详细信息或其他任何信息。 没有人希望任何未经授权的用户都可以访问其数据。 但是不幸的是，市场上有对手以非常聪明的方式抢走这些信息。
There are a lot of hackers and unauthorized users who want access to public data, so they can mislead that information for their benefits. For this purpose, Cryptography standards were introduced to protect our data from such threats.
有许多黑客和未经授权的用户想要访问公共数据，因此他们可能会误导该信息以利于他们。 为此，引入了密码学标准以保护我们的数据免受此类威胁。
In this topic, we will cover what actually Cryptography is, how does it work, and what are its algorithm types. But before moving on, let us discuss some related terms:
在本主题中，我们将介绍密码学到底是什么，密码学如何工作以及其算法类型是什么。 但是在继续之前，让我们讨论一些相关的术语：
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Plain Text: The message which we send to the receiver. For e.g.- “Hello”
纯文本：我们发送给接收者的消息。 例如：“你好”
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Cipher Text: Conversion of that plain text into a non-readable format. For e.g.- “[email protected]#$5”
密文：将纯文本转换为不可读的格式。 例如：“ [受电子邮件保护] ＃$ 5”
Now let’s start with the basics.
现在让我们从基础开始。
Now, suppose there is one sender A who wants to send a message to receiver B who is in the other part of the world. The sender obviously wants this message to be private and no one should access it except the receiver. Here, the only motive is to secure the communication.
现在，假设有一个发送方A想要向位于世界另一端的接收方B发送消息。 发送者显然希望此消息是私有的，除接收者外，任何人都不能访问它。 在此，唯一的动机是确保通信安全。
The sender A will first convert its plain text message into cipher text (unreadable format) using a key. The message is then encrypted and now A sends this message to receiver B over any transmission media.
发送方A将首先使用**将其纯文本消息转换为密文(无法读取的格式)。 然后对消息进行加密，现在A通过任何传输介质将此消息发送给接收方B。
B now receives the message and will require a decryption key to decode the message into a readable format. He then uses the key and decrypts the message to find the original plain text.
B现在接收到该消息，并且将需要解***将消息解码为可读格式。 然后，他使用**并解密消息以查找原始的纯文本。
This is how cryptography works and data is encrypted to secure them from external threats and attacks. There are several different types of cryptography algorithms with each different working methodologies to encrypt the data in the best possible way.
这就是加密的工作方式，并对数据进行加密以保护它们免受外部威胁和攻击。 有几种不同类型的密码算法，每种方法都有不同的工作方法，以最佳方式对数据进行加密。
密码学的类型 (Types of Cryptography)
Cryptography is further classified into three different categories:
密码学又分为三类：
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Symmetric Key Cryptography (Private/Secret Key Cryptography)
对称**密码术 (专用/秘***密码学)
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Asymmetric Key Cryptography (Public Key Cryptography)
非对称**密码学 (公共**密码学)
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Hash Function
散列函数
对称**密码术 (Symmetric Key Cryptography)
Symmetric key cryptography is a type of cryptography in which the single common key is used by both sender and receiver for the purpose of encryption and decryption of a message. This system is also called private or secret key cryptography and AES (Advanced Encryption System) is the most widely uses symmetric key cryptography.
对称**密码术是一种密码术，其中发送者和接收者都使用单个公用**来加密和解密消息。 该系统也称为私钥或秘***加密，而AES(高级加密系统)是使用最广泛的对称**加密。
The symmetric key system has one major drawback that the two parties must somehow exchange the key in a secure way as there is only one single key for encryption as well as decryption process.
对称**系统的一个主要缺点是，由于加密和解密过程只有一个**，因此双方必须以某种方式以安全的方式交换**。
Types: AES (Advanced Encryption Standard), DES, Triple DES, RC2, RC4, RC5, IDEA, Blowfish, Stream cipher, Block cipher, etc. are the types of symmetric key cryptography.
类型： AES(高级加密标准)，DES，Triple DES，RC2，RC4，RC5，IDEA，Blowfish，流密码，分组密码等是对称**密码术的类型。
非对称**密码术 (Asymmetric Key Cryptography)
Asymmetric Key Cryptography is completely different and a more secure approach than symmetric key cryptography. In this system, every user uses two keys or a pair of keys (private key and public key) for encryption and decryption process. Private key is kept as a secret with every user and public key is distributed over the network so if anyone wants to send message to any user can use those public keys.
与对称**密码术相比，非对称**密码术是完全不同且更安全的方法。 在此系统中，每个用户都使用两个**或一对**(私钥和公钥)进行加密和解密过程。 私钥对于每个用户都是秘密，公钥在网络上分发，因此，如果任何人想要向任何用户发送消息，都可以使用那些公钥。
Either of the key can be used to encrypt the message and the one left is used for decryption purpose. Asymmetric key cryptography is also known as public key cryptography and is more secure than symmetric key. RSA is the most popular and widely used asymmetric algorithm.
**中的任何一个都可用于加密消息，而剩下的一个则用于解密。 非对称**密码术也称为公共**密码术，比对称**更安全。 RSA是最流行且使用最广泛的非对称算法。
Types: RSA, DSA, PKCs, Elliptic Curve techniques, etc. are the common types of asymmetric key cryptography.
类型： RSA，DSA，PKC，椭圆曲线技术等是非对称**密码术的常见类型。
散列函数 (Hash Function)
A Hash function is a cryptography algorithm that takes input of arbitrary length and gives the output in fixed length. The hash function is also considered as a mathematical equation that takes seed (numeric input) and produce the output that is called hash or message digest. This system operates in one-way manner and does not require any key. Also, it is considered as the building blocks of modern cryptography.
哈希函数是一种密码算法，它接受任意长度的输入并以固定长度给出输出。 哈希函数也被视为一个数学方程式，它采用种子(数字输入)并产生称为哈希或消息摘要的输出。 该系统以单向方式操作，不需要任何键。 同样，它被认为是现代密码学的基础。
The hash function works in a way that it operates on two blocks of fixed length binary data and then generate a hash code. There are different rounds of hashing functions and each round takes an input of combination of most recent block and the output of the last round.
哈希函数的工作方式是对两个固定长度的二进制数据块进行操作，然后生成哈希码。 哈希函数有不同的回合，每个回合接受最新块与最后一回合的组合的输入。
Types: Some popular hash functions are Message Digest 5 (MD5), SHA (Secure Hash Algorithm), RIPEMD, and Whirlpool. MD5 is the most commonly used hash function to encrypt and protect your passwords and private data.
类型：一些流行的哈希函数是Message Digest 5(MD5)，SHA(安全哈希算法)，RIPEMD和Whirlpool。 MD5是最常用的哈希函数，用于加密和保护您的密码和私人数据。
对称，不对称和哈希函数密码学之间的区别 (Difference between Symmetric, Asymmetric and Hash Function Cryptography)
- Symmetric Key uses single key to encrypt and decrypt the message while asymmetric key uses a pair of keys in which one key is used for encryption and other for decryption whereas hash function does not require any key for encryption as well as decryption. 对称**使用单个**对消息进行加密和解密，而非对称**使用一对**，其中一个**用于加密，另一个**用于解密，而哈希函数则不需要任何**进行加密和解密。
- Symmetric key is relatively faster than asymmetric and hash function but less reliable in terms of security. 对称**比非对称和哈希函数相对快，但在安全性方面则较不可靠。
- Asymmetric key was introduced to overcome the problem of key exchange in symmetric key and hash functions were introduced to provide more security than ever. 引入了非对称**以克服对称**中**交换的问题，并引入了哈希函数以提供比以往任何时候都更高的安全性。
- If the key is compromised over the network then there will loss of both sender and receiver in symmetric key, only loss of key owner in asymmetric key, and in hash function, there is no key to compromise. 如果**在网络上遭到破坏，那么对称**中的发送者和接收者都会丢失，非对称**中的**所有者只会丢失，而散列函数中则不会有泄露的**。
- Asymmetric key has higher complexity than hash function and symmetric key has very less complexity. 非对称**比散列函数具有更高的复杂度，而对称**具有非常低的复杂性。
Conclusion
结论
Encryption of data is much needed in our modern time and the latest schemes may necessarily be the best fit. There are the latest algorithms and techniques being developed as hackers and eavesdroppers have made it tough to secure data to the best possible way. Cryptography is going to enhance more methods in the coming years to make personal data more secure and it’s standards more reliable.
在我们的现代时代，非常需要数据加密，而最新的方案可能必然是最合适的。 随着黑客和窃听者很难以最佳方式保护数据，正在开发最新的算法和技术。 密码学将在未来几年中增强更多的方法，以使个人数据更安全并且其标准更加可靠。
翻译自: https://www.thecrazyprogrammer.com/2019/07/types-of-cryptography.html