Decrypt given data previously encoded with sm4-cbc cipher algo. SM4 in CBC (Cipher Block Chaining) mode, chaining blocks together for secure encryption. CBC mode is used with SM4 to prevent identical plaintext blocks from producing the same ciphertext. SM4-CBC is secure and widely used for encryption 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.