SM4 encryption/decryption

SM(ShangMi)4.0 (formerly known as SMS4.0) was released on March 21, 2012. The relevant standard is GM/T 0002-2012 "SM4 Block Cipher Algorithm" (formerly SMS4 Block Cipher Algorithm). The packet length and key length are both 128bit (that is, 16Byte). In this tool, if the key length is insufficient, it will be filled with 0x00. This tool has not been tested, please give feedback if you find any problems.