Decrypt given data previously encoded with sm4-cfb cipher algo. SM4 in CFB (Cipher Feedback) mode, using feedback to convert the block cipher into a stream cipher. CFB mode was added to SM4 to handle data streams securely while ensuring high performance. SM4-CFB is secure and well-suited for applications that require stream cipher functionality. 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.