Decrypt given data previously encoded with sm4-ecb cipher algo. SM4 in ECB (Electronic Codebook) mode, where each block is encrypted independently. ECB mode for SM4 was implemented for simplicity but has known weaknesses due to the lack of block chaining. SM4-ECB is not recommended for use in modern applications due to vulnerabilities in ECB mode. 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.