Encrypt given data using sm4 cipher algo. SM4 is a block cipher developed by China for use in the country's commercial cryptography systems, offering a 128-bit key and block size. SM4 was standardized as part of China's commercial cryptography policies, and it is used widely in national security and finance applications. SM4 is considered secure and efficient for use in cryptographic applications within China. Our encryption process prepends the IV string used during the encryption process in the encrypted data so that it can be used during decryption.