Encrypt given data using 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 encryption process prepends the IV string used during the encryption process in the encrypted data so that it can be used during decryption.