>
And unless you are adding some kind of virtualizing layer, you don’t have .4% of blocks to play with. You have 0% of blocks.That is a shitty problem to have, there is no perfect solution. If you at all can, change the problem. If that means you need a virtualization layer, use it if possible.
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> I tried to read your pointer, but the link goes no where explaining it. Mind giving a more useful link? It Could be because I’m on mobile.
The first sentence of the link I gave you reads as follows: "Some applications may need to store the authentication tag and the encrypted message at different locations."
Then it shows you the following function that achieves that separation (with zero performance overhead I might add):
int crypto_aead_aes256gcm_encrypt_detached(
unsigned char *ciphertext,
unsigned char *mac,
unsigned long long *mac_size_p,
const unsigned char *message,
unsigned long long message_size,
const unsigned char *additional_data,
unsigned long long additional_data_size,
const unsigned char *always_NULL,
const unsigned char *nonce,
const unsigned char *key);
If
that does not help you, you need more basic training. I recommend Dan Boneh's standford cryptographic course or crypto1O1. And if you need to understand the severity of various attacks at a gut level, you might want to take a look at the cryptopals challenges as well:
http://openclassroom.stanford.edu/MainFolder/CoursePage.php?...
https://www.crypto101.io/
https://www.cryptopals.com/
