Current encryption algorithm explanation

Des (Data Encryption Standard): symmetric algorithm, Data Encryption Standard, fast, suitable for encrypting a large amount of data;

3DES (Triple DES): symmetric des-basedAlgorithmTo encrypt a piece of data three times with three different keys, with higher strength;

RC2 and RC4: symmetric algorithms that use variable-length keys to encrypt a large amount of data, faster than DES;

Idea (International Data Encryption Algorithm) International Data Encryption Algorithm, uses a 128-bit key to provide very strong security;

RSA: A Public Key algorithm that supports variable-length keys. The length of the file block to be encrypted is also variable. asymmetric algorithms;

DSA (Digital Signature Algorithm): digital signature algorithm, which is a standard DSS (Digital Signature Standard). It is not an encryption algorithm strictly;

AES (Advanced Encryption Standard): Advanced Encryption Standard, symmetric algorithm, is the next generation of encryption algorithm standard, fast, high security level, currently an implementation of the AES standard is Rijndael algorithm;

Blowfish uses a variable-length key, which can contain up to 448 bits and runs fast;

MD5: Not an encryption algorithm. It can only be a digest algorithm.

A brief description of the MD5 algorithm can be: MD5 processes input information in 512-bit groups, and each group is divided into 16 32-seat groups, after a series of processing, the algorithm output consists of four 32-bit groups. After these four 32-bit groups are cascade, a 128-bit hash value is generated.

In the MD5 algorithm, you first need to fill in the information so that the result of the length of the byte for 512 is equal to 448. Therefore, the byte length (bits length) of the information is extended to N * 512 + 448, that is, N * 64 + 56 bytes (bytes), and N is a positive integer. The filling method is as follows. Fill in one and countless zeros after the information until the above conditions are met. Then, append a length of the prefill information in 64-bit binary format to the end of the result. After these two steps, the length of the current information byte = N * 512 + 448 + 64 = (n + 1) * 512, that is, the length is exactly an integer multiple of 512. The reason for this is to meet the requirements for the length of information in subsequent processing. (For details, refer to the MD5 Algorithm entry)

Ssf33, ssf28, scb2 (SM1): Commercial algorithms hidden and undisclosed by the Office of National cryptography are not allowed to be used in civil and commercial use in China;