What does DES mean?

DES, known as the data encryption standard, is a block algorithm using key encryption.

1977 was determined as the federal data processing standard (FIPS) by the National Bureau of Standards of the US federal government, and was authorized to be used in non-confidential government communications, and then the algorithm was widely spread internationally. It should be noted that DES, as an algorithm, is called Data Encryption Algorithm (DEA) in some literatures, which has been distinguished from DES as a standard.

Extended data:

1, data encryption standard

The original idea of DES can refer to Engelmar machine in Germany during World War II, and the basic idea is basically the same. Traditional cryptographic encryption originated from the ancient idea of cyclic shift, and Enigma machine diffused fuzziness on this basis. But the essential principle is the same. Modern DES does the same thing at the binary level: it replaces fuzziness and increases the difficulty of analysis.

2. Folding encryption principle

DES uses a 56-bit key and an additional 8-bit parity bit to generate packets with a maximum of 64 bits. This is an iterative block cipher, which uses a technique called Feistel, in which the encrypted text block is divided into two halves. Using subkeys to apply a cyclic function to half of them, and then XOR the output with the other half; Then the two halves are exchanged, and this process will continue, but the last cycle will not be exchanged. DES uses 16 cycles and uses four basic operations: XOR, permutation, substitution and shift.

References:

Baidu encyclopedia -DES