Data encryption algorithm is a symmetric encryption algorithm and is the most widely used key system, especially in protecting the security of financial data; cryptographic algorithm is the collective name for encryption algorithm and decryption algorithm. It is a cryptographic system. At its core, a cryptographic algorithm can be seen as a combination of exchanges. When the input is plaintext, after these transformations, the output is ciphertext. This process is an encryption algorithm.
Data Encryption Algorithm (Data Encryption Algorithm, DEA) is a symmetric encryption algorithm and is probably the most widely used key Systems, especially in securing financial data, were originally developed with DEA embedded in hardware. Usually, automated teller machines (Automated Teller Machines, ATMs) use DEA. It originated from IBM's research work, and IBM also owned the patent rights for it for several years, but after it expired in 1983, it was in the public domain, allowing it to be used without patent royalties under certain conditions. It was officially adopted by the US government in 1997.
Features
Cryptographic algorithm is the collective name for encryption algorithm and decryption algorithm. It is the core of the cryptographic system. A cryptographic algorithm can be viewed as a combination of exchanges. When the input is plaintext, after these transformations, the output is ciphertext. This is the process of encrypted exchange, and the cryptographic algorithm at this time is called an encryption algorithm.
On the contrary, when the input is ciphertext, after password transformation, the output is plaintext. This is the process of decryption and exchange. At this time, the cryptographic algorithm is called a decryption algorithm. Commonly used encryption algorithms are: AES, RSA/ECC, Diffie-hellman, SHA-1/SHA-256.
Encryption Standard
The original idea of DES can refer to the German Enigma machine in World War II, and its basic idea is roughly the same. Traditional cryptographic encryption is derived from the ancient idea of cyclic shift, and the Enigma machine performs diffusion obfuscation on this basis. But the essential principles are the same. Modern DES does the same thing at the binary level: replaces obfuscation and makes analysis more difficult.
Encryption principle
DES uses a 56-bit key and additional 8 parity bits (the 8th bit of each group is used as a parity bit) , resulting in a maximum packet size of 64 bits. It is an iterative block cipher that uses a technique called Feistel, in which the encrypted block of text is split in half.
Apply a loop function to one half using the subkey, and then XOR the output with the other half; the halves are then swapped, and the process continues without swapping the last loop. DES uses a 16-round loop and uses four basic operations: XOR, permutation, substitution, and shift operations.
Triple DES
A common variant of DES is Triple DES (3DES), which uses a 168 (56*3)-bit key to encrypt the data three times (3 A mechanism that uses DES for the first time; it usually (but not always) provides extremely strong security. Triple DES is backwards compatible with DES if all three 56-bit subelements are the same.
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