The uses of public key encryption algorithms mainly include two aspects: secure communication and digital signatures.

1. Secure communication

Public key encryption algorithm allows secure communication between multiple people. Everyone can generate a pair of public and private keys, the public key is used to encrypt data, and the private key is used to decrypt data. The sender uses the receiver's public key to encrypt the information, and then the receiver uses its own private key to decrypt it, thus ensuring the security of the information during transmission.

2. Digital signature

Public key encryption algorithm can also be used for digital signatures to verify the integrity and authenticity of information. The sender signs the message using his or her private key, and the receiver uses the sender's public key to verify the signature. If the signature is successful, the information has not been tampered with, thus ensuring the integrity and authenticity of the information.

Symmetric key cryptography

The so-called symmetric key cryptography is a cryptography system in which the encryption key and the decryption key are the same. The data encryption standard DES is a symmetric key cryptography system. It was developed by IBM and attracted great attention internationally after it was designated as a federal information standard by the United States in 1977. ISO once adopted DES as a data encryption standard.

DES is a block cipher. Before encryption, the entire plaintext is grouped. Each group is 64 bits long of binary data. Then each 64-bit binary data is encrypted to generate a set of 64-bit ciphertext data. Finally, the groups of ciphertexts are concatenated to obtain the entire ciphertext.