Expand on gas costs about aztec-v1 HOT 4 CLOSED

Hi WyseNynja, the raw gas costs of AZTEC transactions are dominated by the elliptic curve 'scalar multiplcations' performed by the smart contract. The number of these operations is the following:

3 * (number of input notes) + 4 * (number of output notes) - 1

Currently these operations cost 40,000 gas. On top of that, we require one 'bilinear pairing' comparison which costs 260,000 gas. Finally, it costs around 13,000 gas to add a note into a transaction as input data.

On top of that, every output note requires 20,000 gas of storage space. Every input note in a transaction frees up 10,000 gas (because we're clearing a storage variable). Finally, there's around 20,000 gas of miscellainous smart contract logic. This brings the gas costs for an AZTEC transaction to roughly:

123,000 * (number of input notes) + 193,000 * (number of output notes) + 240,000

As @PaulRBerg mentioned, EIP-1108 will cut these costs considerably.

from aztec-v1.

900,000 is not the cost for a basic transfer of 1 input and output note, but for 2 input and output notes.

So the gas cost is 10x not 42.9x larger. It is also important to note that this is the first released version of the protocol and, generally speaking, there is no free lunch. Privacy comes at a cost. Thankfully, EIP-1108 will get it down by a factor of ~2.5x.

from aztec-v1.

How common will 1 input, 1 output notes actually be though? I feel like 1 or 2 in and 2 out are going to be more common transactions.

I'm not asking for a free lunch here. I'm simply asking for clear documentation of transaction costs.

from aztec-v1.

Following up, 1-input 1-output transactions occur in bilateral trades between different AZTEC notes. Imagine I have a note and I send you all the tokens I have by destroying the note and issuing a new one with a viewing key you know.

from aztec-v1.