Symmetric encryption asymmetric encryption irreversible encryption algorithm

According to different key types, modern cryptographic technologies can be divided into two types: symmetric encryption algorithm (private key cryptography system) and asymmetric encryption algorithm (public key cryptography system ).

1. In symmetric encryption algorithms, data encryption and decryption use the same key, so its security depends on the security of the key held.
Symmetric encryption algorithms provide fast encryption and decryption speed, high encryption strength, and open algorithms.
The disadvantage is that it is difficult to achieve secret distribution of keys. In the case of a large number of users, key management is complex, and identity authentication and other functions cannot be completed, which is not convenient for applications in an open network environment.
Symmetric encryption algorithms are characterized by public algorithms, low computational workload, fast encryption speed, and high encryption efficiency.
Currently, the most famous symmetric encryption algorithm is the Data Encryption Standard des. However, because the traditional des has only 56-bit keys, it does not meet the requirements of distributed open networks for data encryption security. European Data Encryption Standard (IDEA). Currently, the most powerful symmetric encryption algorithm is Advanced Encryption Standard (AES). AES provides a 128-bit key, the encryption strength of 128-bit AES is more than 1021 times that of 56-bit des ..

The symmetric encryption algorithm processes the plaintext (original data) and encryption key of the Data sender together with the special encryption algorithm to make it into a complex encrypted ciphertext and send it out. After receiving the ciphertext, the recipient needs to use the Encrypted Key and the inverse algorithm of the same algorithm to decrypt the ciphertext to restore it to readable plaintext. In the symmetric encryption algorithm, only one key is used. Both the sender and receiver use this key to encrypt and decrypt the data. Therefore, the sender must know the encryption key in advance.
The disadvantage is that both parties use the same key, and the security is not guaranteed. Assume that two users need to use symmetric encryption to encrypt and exchange data, then the user needs at least two keys for exchange and use. If there are n users in the enterprise, the entire enterprise requires n × (n-1) keys.

2 asymmetric encryption algorithms
The asymmetric encryption algorithm uses two key pairs (Public Key or encryption key and private key or decryption key) that are completely different but completely matched-public key and private key. Only a matching pair of public and private keys can be used to encrypt and decrypt files using asymmetric encryption algorithms. The public key is used to encrypt the plaintext, and the private key is used to decrypt the ciphertext. the sender (the encrypted) knows the public key of the recipient, and only the recipient (the decrypted) can decrypt the ciphertext) the only person who knows his/her private key. The basic principle of asymmetric encryption algorithms is that if the sender wants to send encrypted information that can only be interpreted by the recipient, the sender must first know the recipient's public key, then, the recipient's public key is used to encrypt the original text. After receiving the encrypted ciphertext, the recipient can use its own private key to decrypt the ciphertext.
The widely used asymmetric encryption algorithms include RSA and DSA proposed by the US National Bureau of Standards.
Asymmetric encryption algorithms have good confidentiality and eliminate the need for end users to exchange keys. However, encryption and decryption take a long time and are slow, it is not suitable for encrypting files, but only for encrypting a small amount of data.

Symmetric encryption algorithms, asymmetric encryption algorithms, and irreversible encryption algorithms can be applied to data encryption, identity authentication, and secure data transmission.

3 irreversible encryption algorithms

Irreversible encryption algorithms do not require keys during encryption. After a plaintext is input, the system processes the encrypted data directly into a ciphertext. the encrypted data cannot be decrypted, only when the plaintext is re-entered and processed by the same irreversible encryption algorithm again, the same encrypted ciphertext is obtained and re-identified by the system. Obviously, in this type of encryption process, encryption is self-encryption, and decryption is self-encryption. The so-called decryption is actually re-encryption, and the applied "password" is the input plaintext. The irreversible encryption algorithm does not have the key storage and distribution issues and is suitable for distributed network systems. However, due to the complexity of encryption computing, the workload is quite heavy. It is usually used only when the data volume is limited, for example, password encryption widely used in computer systems uses irreversible encryption algorithms. In recent years, with the continuous improvement of computer system performance, the application field of irreversible encryption is gradually increasing. Among the many irreversible encryption algorithms used in computer networks, the MD5 Algorithm invented by RSA and the irreversible encryption standard self-built (Secure Hash Standard: Safe and messy Information Standard) proposed by the National Bureau of Standards).

 

Famous

1 symmetric des

2 asymmetric RSA

3 irreversible MD5

Symmetric encryption asymmetric encryption irreversible encryption algorithm