how can i decrypt huawei HG531s v1 config file?

I have tried to follow this guide

The firmware file

i looked into all the lib files using IDA and this what i found .(ATP_GetInfo1 ATP_GetInfo2 ATP_GetInfo3 ATP_GetInfo4) are in libhttpapi.soATP_GetInfo2 is in libcfmapiATP_GetInfo3 is in libmsgapi.soATP_GetInfo4 is in libatputil.so

the tutorial says

ATP_GetInfo1 is in libxmlapi.soATP_GetInfo2 is in libhttpapi.soATP_GetInfo3 is in libcfmapi.soATP_GetInfo4 is in libmsgapi.so

the lib files.zip

here are the 4 long hex strings from the functions ATP_GetInfo4 from libatputil.so 3C1C0002279C4FAC0399E021108000092402000110A00007000000008F838024000010212463F0E0AC83000024030010ACA3000003E0000800000000ATP_GetInfo3 from libmsgapi.so 3C1C0002279CAEF80399E021108000092402000110A00007000000008F83802400001021246341D4AC83000024030010ACA3000003E0000800000000ATP_GetInfo2 from libcfmapi.so3C1C0003279C8B5C0399E021108000092402000110A00007000000008F83802400001021246338CCAC83000024030010ACA3000003E0000800000000ATP_GetInfo1 from libhttpapi.so 3C1C0002279C23400399E021108000092402000110A00007000000008F838024000010212463C890AC83000024030010ACA3000003E0000800000000i get error . decrypted_data = decrypted_data.decode().rstrip('\0')UnicodeDecodeError: 'utf-8' codec can't decode byte 0xef in position 0: invalid continuation byte

i think ATP_CFM_ExtExportEncryptedCfgFile' and 'ATP_CFM_ExtImportEncryptedCfgFile and ATP_CFM_ExtDecryptedCfgFile and cfmDecryptCfgFileAes functions in libcfmapi.so are important but don't know what to do with them . as this comment says https://hg658c.wordpress.com/2015/03/17/hg658c_configtool/comment-page-1/#comment-41

and especially this one ATP_CFM_ExtReadCfgFile it have a hell of interesting functions connected to it