### What are the symmetric encryption algorithms

Symmetric encryption algorithms are used to encrypt sensitive data and other information, and commonly used algorithms include:

1, DES algorithm: data encryption standard, faster, and suitable for encrypting large amounts of data.

2. 3DES algorithm: It is based on DES and encrypts a piece of data three times with three different keys, with higher strength.

3. AES algorithm: Advanced Encryption Standard, is the next generation of encryption algorithm standard, fast, high security level.

Symmetric encryption algorithm: It is an encryption algorithm with earlier application and mature technology. In symmetric encryption algorithm, the data sender will be the plaintext and encryption key together with a special encryption algorithm processing, so that it becomes a complex encryption cipher text sent out.

### Commonly used symmetric encryption algorithms

Commonly used symmetric encryption algorithms:

DES3DESAES

1, DES (DataEncryptionStandard)

DES encryption algorithms come from IBM’s research, and later officially adopted by the U.S. government, and then began to be widely circulated, but in recent years the use of It has been used less and less in recent years because DES uses a 56-bit (8-byte) key that can be cracked in less than 24 hours with modern computing power

. Nevertheless, in some simple applications, we can still use DES encryption algorithm

Features: data encryption standard, faster, suitable for encrypting a large amount of data occasions

2, 3DES (TripleDES)

Based on DES, a piece of data is encrypted three times with three different keys, with higher strength

Based on DES, a piece of data is encrypted three times with three different keys, with higher strength

Based on DES, a piece of data is encrypted three times with three different keys. Three times encryption, higher strength

3DES is a triple data encryption, and can be inverse deduction of an algorithmic scheme. However, since the algorithm of 3DES is public, the algorithm itself has no key to speak of, and mainly relies on a unique key to ensure the security of data encryption and decryption. So far, there is still no one can crack 3DES.

Features: data encryption standard, faster, and secure,

3, AES (AdvancedEncryptionStandard) recommended

Advanced Encryption Standard in cryptography ( AdvancedEncryptionStandard, AES), also known as Rijndael encryption, is a block encryption standard adopted by the U.S. federal government.

The standard, which replaced the original DES (DataEncryptionStandard), has been analyzed by multiple parties and is widely used around the world. After a five-year selection process, the Advanced Encryption Standard was published by the National Institute of Standards and Technology (NIST) in FIPSPUB 197 on November 26, 2001, and became an active standard on May 26, 2002.In 2006, the Advanced Encryption Standard has become one of the most popular algorithms for symmetric key encryption [1].

The algorithm was designed by Belgian cryptographers Joan Daemen and Vincent Rijmen, and combined the names of the two authors, named after Rijdael, to contribute to the selection process of the Advanced Encryption Standard. (Rijdael is pronounced “Rhinedoll.”)

Advanced Encryption Standard (AES) is a next-generation standard for encryption algorithms that is fast, secure, and supports encryption with 128-, 192-, 256-, and 512-bit keys.

Features: data encryption is more standardized, faster, more secure, more popular

### Is AES encryption algorithm symmetric key or asymmetric key?

Aes is a symmetric encryption algorithm, the biggest feature of this algorithm is that the encryption key and the decryption key are the same. In addition, aes is relatively simple, and is widely used in data stream encryption.

The AES encryption standard, also known as the Advanced Encryption Standard (AES) Rijndael encryption, is a 21st-century encryption standard designed to replace DES by the National Institute of Standards and Technology (NIST).

AES encryption algorithm is an advanced encryption standard in cryptography, the encryption algorithm uses a symmetric packet cipher system, the minimum support for the key length of 1219256, the packet length of 128 bits, the algorithm should be easy to implement a variety of hardware and software.

AES belongs to symmetric encryption, common symmetric encryption methods and DES, 3DES, Blowfish, RC2, and the state secret SM4. asymmetric encryption symmetric encryption is fast and convenient, but there is a drawback – the key is easy to be stolen or cracked. Asymmetric encryption avoids this problem very well.

These two algorithms are standard cryptographic algorithms that are widely used. aes is a symmetric encryption algorithm that is often used to encrypt data, and rsa is an asymmetric (public key) encryption algorithm that is often used to encrypt keys used in asymmetric encryption, or to digitally sign files, etc.

Aes is a symmetric encryption algorithm that is often used to encrypt data.

AES encryption is an advanced encryption standard, a block cipher standard. It is a symmetric cipher, meaning that the same key is used for encryption and decryption. the encryption often used by WPA/WPA2 is the AES encryption algorithm.

### Briefly describe the basic principles of encryption technology, and point out what are the commonly used encryption system and its representative algorithms

1, symmetric encryption algorithms

Symmetric encryption algorithms are used to encrypt sensitive data and other information, commonly used algorithms include:

DES (DataEncryptionStandard): data encryption standard, the speed of faster. It is suitable for encrypting a large amount of data.

3DES (TripleDES): Based on DES, a piece of data is encrypted three times with three different keys, with higher strength.

AES (AdvancedEncryptionStandard): Advanced Encryption Standard, the next generation of encryption algorithms standard, fast, high security level;

Algorithm Principle

AES algorithm is based on the permutation and substitution operations. Arrangement is the rearranging of data, and substitution is the replacement of one unit of data with another.AES uses several different methods to perform the arrangement and substitution operations.

2. Asymmetric Algorithms

Common asymmetric encryption algorithms are as follows:

RSA: Invented by the RSA company, it is a public-key algorithm that supports variable-length keys, and the length of the block of the file that needs to be encrypted is also variable;

DSA (DigitalSignatureAlgorithm): Digital Signature Algorithm, a standard DSS (Digital Signature Standard);

ECC (EllipticCurvesCryptography): Elliptic Curve Cryptography.

Algorithmic Principles – Difficulties on Elliptic Curves

The ECDLP problem of discrete logarithms on elliptic curves is defined as follows: given a prime number p and an elliptic curve E, for Q = kP, find a positive integer k less than p, knowing P, Q. It can be shown that it is relatively easy to compute Q from k and P, while it is more difficult to compute k from Q and P it is more difficult to compute k.

Corresponding the addition operation in elliptic curves to the modal multiplication operation in discrete logarithms, and the multiplication operation in elliptic curves to the modal power operation in discrete logarithms, we can build the corresponding cryptographic regime based on elliptic curves.