State Secret is a domestic cryptographic algorithm approved by the State Cryptography Bureau, which mainly includes SM 1, SM2, SM3 and SM4. At present, SM 1 algorithm has not been published, and it can only be integrated in the chip. At present, SM2, SM3 and SM4 algorithms are widely used, and their usage is different. SM2 public key encryption algorithm is one of the national secret public key encryption standards, which was issued by the National Cryptography Administration on February 20 10.

SM2 is an asymmetric encryption algorithm, which uses public key encryption and private key decryption, and is superior to RSA algorithm in security and operation speed. SM2 public key encryption is suitable for encrypting short data, such as session keys and messages. SM2 public key encryption not only encrypts data, but also provides tamper-proof function, that is, tampered or forged ciphertext can be found during decryption.

Brief introduction of encryption algorithm

Therefore, the message encrypted with SM2 public key does not need additional verification mechanism, and the length of the message encrypted with SM2 public key will increase by less than 100 bytes, so the encryptor should pay attention when preparing the buffer. SM3 is an irreversible encryption algorithm, similar to md5, and is usually used for signature.

SM4 is a symmetric encryption algorithm, which can be used to replace international algorithms such as DES/AES. SM4 algorithm and AES algorithm have the same key length and packet length, both of which are 128 bits. After the message is encrypted with SM2 public key, the length will not increase by more than 100 bytes, so the encryptor should pay attention when preparing the buffer.