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META: reduce gas consumption
This issue affects everybody except Nick so I added all developers to the Assignees (except Nick)
Latest estimation from Tore on the gas consumption of elliptic math:
version without Pedersen Commtment: 15k gas and with pedersen commitment it will be 40k gas
- [x] BN curve (and consequently, Pedersen Commit)
- [ ] ~~Applying Barretts Reduction~~ Apply rejection sampling (see PR #87 and PR #88)
- [ ] Optimising
asn:INTEGERto byte32 converstion - [x] Reduce transaction size: by not inclduing the EC parameter or include in a condensed
- [x] Reduce transaction size: by not including the signature in UseTicket. This is closed in PR #89.
- [x] Reduce transaction size: reduce the size of proof by not repeating Pederson Commit. This is closed in PR #89.
- [ ] Reduce transaction size: by including compressed EC point (@jot2re @JamesSmartCell said that this unlikely leads to gas reduction)
Quote @JamesSmartCell on the progress:
I'll continue the integration and then update when I have his new algorithm
Results from removing elements of the smart contract:
Only EC math (ie no decoding of any kind): 58,977 EC math plus forming the Challenge (concatenate, hash and modulo): 68,114 EC math, form challenge plus decode coordinates from hardcoded bytes: 141,494 EC math, form challenge, decode coordinates from DER decode: 208,118
Looks like the optimisation that will payback the most is the coordinate decode function, I'll take a look at that first, followed by optimising the DER decode.
Good news, after hand optimising the less efficient code I was able to bring the whole function operation down to 120,213 Gas.
There's still a couple of areas left that can be optimised as when I wrote them I wrote them to be generic, since we know what data is expected that can be optimised a bit further.
After further hand optimisation, 73,560 Gas.
This will be the final gas spend for this contract, with the 'biased' array hash (which is vulnerable). I will move onto the new implementation outlined by Tore.
After further hand optimisation, 73,560 Gas.
This will be the final gas spend for this contract, with the 'biased' array hash (which is vulnerable). I will move onto the new implementation outlined by Tore.
You mean this is reduced to 73.5 K? Marvelous!
EC math, form challenge, decode coordinates from DER decode: 208,118