Decrypt given data previously encoded with 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 decryption process assumes the IV string is prepended in the encoded string during the encryption process. You can not decrypt and get the correct results if the IV or passphrase mismatch occurs between encryption and decryption process.