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Automatically merged updates to draft EIP(s) 1108 (#2067) 

Hi, I'm a bot! This change was automatically merged because:

 - It only modifies existing Draft or Last Call EIP(s)
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Antonio Salazar Cardozo 2019-05-24 11:32:38 -04:00 committed by EIP Automerge Bot
parent a573835f23
commit 9af2a9b1ef
1 changed files with 19 additions and 1 deletions
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EIPS/eip-1108.md
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@ -59,7 +59,19 @@ Following is a table with the current gas cost and new gas cost:
The gas costs for `ECADD` and `ECMUL` are updates to the costs listed in
EIP-196, while the gas costs for the pairing check are updates to the cost
listed in EIP-197. Updated gas costs have been adjusted to the less performant
client which is Parity, according to benchmarks<sup>[3]</sup>. The updated gas costs are scaled relative to the `ecrecover` precompile. i.e. in the benchmark, `ecrecover` ran in 116 microseconds. If we consider 3,000 gas the fair price for `ecrecover`, we can obtain a metric how much gas should be charged per microsecond of an algorithm's runtime, and use that to price the elliptic curve precompiles.
client which is Parity, according to benchmarks<sup>[3]</sup>.
To come up with these updates gas costs, the performance of the `ecrecover` precompile
was measured at 116 microseconds per `ecrecover` invocation. Assuming the `ecrecover`
gas price is fair at 3,000 gas, we get a price of 25.86 gas per microsecond of a precompile
algorithm's runtime. With this in mind, the pairing precompile took 3,037 microseconds to
compute 1 pairing, and 14,663 microseconds to compute 10 pairings. From this, the pairing
algorithm has a fixed 'base' run-time of 1,745 microseconds, plus 1,292 microseconds per
pairing. We can split the run-time into 'fixed cost' and 'linear cost per pairing'
components because of the structure of the algorithm.
Thus using a 'fair' price of 25.86 gas per microsecond, we get a gas formula of
~`35,000 * k + 45,000` gas, where `k` is the number of pairings being computed. [4]
[1]- Per [EIP-196](https://github.com/ethereum/EIPs/blob/984cf5de90bbf5fbe7e49be227b0c2f9567e661e/EIPS/eip-196.md#gas-costs).
@ -67,6 +79,8 @@ client which is Parity, according to benchmarks<sup>[3]</sup>. The updated gas c
[3]- [Parity benchmarks.](https://gist.github.com/zac-williamson/838410a3da179d47d31b25b586c15e53)
[4]- [PR comment clarifying gas cost math](https://github.com/ethereum/EIPs/pull/1987#discussion_r280977066).
## Rationale
### Existing protocols would benefit immensely from cheaper elliptic curve cryptography
@ -116,3 +130,7 @@ Both the Parity and Geth clients have already implemented cryptographic librarie
* [Geth bn256 library (golang)](https://github.com/ethereum/go-ethereum/tree/master/crypto/bn256/cloudflare)
* [MCL, a portable C++ pairing library](https://github.com/herumi/mcl)
* [Libff, a C++ pairing library used in many zk-SNARK libraries](https://github.com/scipr-lab/libff)
## Copyright
Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).