Encryption SM2-SM4 C# interacts with OpenSSL

SM2 algorithm is the ECC elliptic curve cryptography mechanism, but different from the international standards such as ECDSA and ECDH in terms of signature and key exchange, it adopts a more secure mechanism.In addition, SM2 recommends a 256-bit curve as the standard curve.< br > SM2 standard includes four parts: general rules, digital signature algorithm, key exchange protocol, and public key encryption algorithm.< br > SM4 symmetric algorithm is a grouping algorithm for wireless LAN products.The packet length of the algorithm is 128 bits and the key length is 128 bits.Both the encryption algorithm and the key expansion algorithm adopt 32-round nonlinear iterative structure.The structure of the decryption algorithm is the same as that of the encryption algorithm, except that the use order of the wheel key is reversed.< br > This algorithm adopts nonlinear iterative structure, each iteration is given by a wheel function, in which the wheel function is composed of a nonlinear transformation and a linear transformation, and the nonlinear transformation is given by the s-box.Where rki is the wheel key and the synthetic permutation T constitutes the wheel function.The generation of the wheel key is similar to the above process, which is generated by the encryption key as the input. The linear transformation in the wheel function is different, and some parameters are different.See SM4 standard for detailed description and examples of SM4 algorithms.< br > The code details the Csharp version of SM2/SM4 encryption and decryption as well as Csharp and Openssl encryption and decryption interaction.Detailed procedures and code are provided.< br >