What is Public Key Encryption?

Public key encryption, also known as asymmetric (key) encryption, belongs to the second discipline of network security under communication technology. Key). It solves the issue and management of keys and is the core of current commercial passwords. In the public key encryption system, what is not public is the private key, and what is public is the public key.

This idea was first proposed by Ralph C. Merkle in 1974, and later in 1976. Two scholars, Whitfield Diffie and Martin Hellman

It refers to a pair of encryption key and decryption key. These two keys are mathematically related. The information obtained after being encrypted with a user's key can only be decrypted with the user's decryption key. If one is known, the other cannot be calculated. Therefore, if one of the keys is disclosed, the secret nature of the other will not be compromised. Public key

The so-called symmetric key cryptosystem, that is, the encryption key and the decryption key are the same. ^[2]

The data encryption standard DES belongs to a symmetric key cryptosystem. It was developed by IBM, and was set as a federal information standard by the United States in 1977, which has attracted great attention internationally. ISO used DES as a data encryption standard.

DES is a block cipher. Before encryption, the entire plaintext is grouped. Each group is 64-bit long binary data. Each 64-bit binary data is then encrypted to produce a set of 64-bit ciphertext data.

Finally, the ciphertexts of each group are concatenated to obtain the entire ciphertext. ^[1]