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