What are the characteristics of symmetric key system and public key cryptography system?

The characteristics of the symmetric key system are: fast encryption and decryption speed and high security strength, but the key is difficult to manage and transmit, and is not suitable for use alone in the network; the characteristics of the public key cryptography system are: high confidentiality strength, Key distribution and management are simple, and digital signatures are easy to implement.

#The operating environment of this article: Windows 7 system, Dell G3 computer.

Symmetric cryptographic system

Symmetric cryptographic system, also known as single-key cryptographic system, refers to the encryption key and decryption key. Cryptosystem with the same key. The confidentiality of this cryptographic system mainly depends on the confidentiality of the key, and its encryption and decryption algorithms are public.

To ensure the security of the symmetric key cryptography system, the encryption algorithm must be complex enough, and the key must be kept secret and have a large enough key space, so that the attacker can intercept the ciphertext and know the encryption In the case of algorithm, the plaintext still cannot be restored. The most influential symmetric key cryptography system is the data encryption standard DES issued by the American National Bureau of Standards in 1977.

Characteristics of the symmetric cryptographic system:

• Fast encryption and decryption speed

• High security strength

• The key is difficult to manage and transmit, and is not suitable for use alone in the network

Public key cryptography system

The public key cryptography system is an asymmetric key. The advantage is that it is fast in calculation and easy to generate the key.

(1) High confidentiality strength

The theoretical basis is based on the difficulty of factoring large prime numbers in number theory. When n is greater than 2048 bits, the current algorithm cannot decipher RSA within an effective time .

(2) Key distribution and management are simple

In the RSA system, the encryption key and the decryption key are different and separated. The encryption key can be made public, and the decryption key is kept secretly by the user. The amount of secretly kept keys is reduced, which makes key distribution more convenient and facilitates key management.

(3) Digital signatures are easy to implement

In the RSA system, only the recipient uses its own decryption key to sign the plain text, and anyone else can use the public key to sign the signed text. Verified, but cannot be faked.

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