ZTE AES-256-CBC Encrypted backup config file

i tried router pass view tool on (a closed source one) it’s able to decrypt the older version of it V3.1. tested on two routers of it and it gave me this output

Encrypted Data Start Position: 227
Encryption Algorithm: AES-128
Encryption Key: 34303263333864653339626564363635
Compression: zlib / deflate

and

Encrypted Data Start Position: 227
Encryption Algorithm: AES-128
Encryption Key: 4772574D33487A264C54767A26665E39
Compression: zlib / deflate     

also someone told me

the encryption algorithm was changed to AES-256-CBC and key and iv are
derived from MAC, SerialNumber and EncryKey.

snprintf(&g_keySeed, 65, "%s%sMcd5c46e", EncryKey, SN);
snprintf(&g_ivSeed, 65, "G21b667b%s%s", MAC, EncryKey);

sha256(key_seed, key_seed_len, &aes_key);

sha256(iv_seed, iv_seed_len,&aes_iv);

without telling me what’s that encrykey and didn’t reply again.

the firmware and config files