Ok, I misunderstood the definition of aggregation, I believed it was similar to a multiparty signature, my bad.
I believed that we could generate the transactions, as usual, but other signature-message, and then let the miner sum the signatures, and verify using the summed public key. Then the block should be this multi-signature and summed excess instead of separate kernels, but elseway similar.
I found that TariLabs go a bit into detail and that a key cancellation attack could hit this naive scheme.
However, I do not fully understand what this attack would mean in this scenario.
Would it give him the ability to create and sign a transaction (where he knows the amount) in such a manner that he does not need to know the ‘private-key’?
Edit
Utilising this naive scheme introduces a straightforward attack that can steal funds by using the key cancellation attack without the attacker needing to know any private keys.
Example:
Say that Alice transfer 5 coins to Bob. She does not know the private-key under which they are stored; however, she knows the amount.
Say that Alice mines a block before Bob have spent the funds. She can then generate two fake transactions;
One using the funds she sent to Bob as an input, and an output with the same amount (5 coins) but a private-key picked by Alice herself.
And another transaction by Alice, where she adds an additional output with 0 coins, but a private-key that ‘offsets’ the excess.
Looking at the transactions individually, they will fail but summed they can create a valid signature that they will satisfy.
Thank you for your time and answers. It was a great help for me 