On this forum, someone(RomanZ?) recomemded not to use encrypted secret keys (stars with "D" instead of "A") as they require more work (checksum) and hence more load on ARMs. I just got an idea that if substitution cipher is used instead of AES, is there any way of not having to do more checksums (assuming sum of all bytes is the checksum, it wont change even after encryption). And the encryption would be fast as well and it is compressible as well. And if another encryption is done after compression, it is more hard to break I guess. I am not an expret, just some thoughts. Any possibility?