BLAKE2b F Compression Function Precompile
#152
Comments
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Great! I think this is a good feature to add. It will allow "Project Alchemy" — BTCRelay-style interoperation between the Zcash and Ethereum blockchains, and it may also be useful as a general purpose secure hash function which is more efficient than SHA3. |
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Please add some more details about the gas costs. I guess they should at least depend on |
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In the earlier EIP about a precompiled full BLAKE2b, the following conversation happened about gas costs:
Okay, so for this new proposal — the precompiled I suggest the gas cost for invoking (I still don't understand what Zaki's rationale is for making the gas cost of BLAKE2b precompile be the same as gas cost of SHA3 precompile.) |
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Oh, good point about the gas cost of rounds. I propose that |
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I think picking hard numbers right now would be somewhat pointless, until we can actually measure compute time in different clients. You're right that the gas is now going to be proportional to the number of rounds now, as opposed to the number of bytes. |
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I'd rather implement 64-bit operations in the EVM. |
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I think this would be a useful project, and I'd like to see it get restarted! |
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Okay, to make progress on this, I propose that we temporarily table @gcolvin's alternative suggestion of 64-bit arithmetic (interesting idea, but let's move it to a separate EIP), and satisfice on the gas costs (I still want the @tjade273, @vbuterin: What can we do to help make progress on this. Would it help if one of the Zcash team provided an implementation in some programming language? |
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Agreed. |
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Sorry if the project has slowed down a bit, I've been quite busy with school; I have a break coming up and I hope to get a PoC with a few of the implementations done. Right now, I think the priority should be to get a precompile implemented in the Go and Rust implementations, since those are the most widely used. To that end, if anyone has experience with FFIs in Go or Rust, that'd be really helpful. As for gas costs, I think it will become clear what a reasonable price is based on some simple benchmarking once we have an implementation in major clients |
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Great! @gcolvin agrees to move the 64-bit-arithmetic idea to another thread (and please let me know so I can subscribe to that one), and we all agree to defer decision about precise gas costs. I'll see if I know someone who wants to take a stab at implementing it in Rust. |
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The Go precompile is almost complete, and the benchmarks look good: the BLAKE2 precompile is almost exactly twice as fast as the SHA3 on my laptop. That's using a pretty un-optimized, pure-go implementation. |
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@tjade273 So I was looking at this and I asked Veorq about it and it looks to me like you passing in 128 bits of counter data into the compression function. I believe that is supposed to be max 64 bits. It may not matter but it requires more invasively changing an existing Blake implementation to conform to your api like I'm doing with the Rust impl. |
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@zmanian The specification says that the compression function takes a
i.e. 128 bits. This is consistent with the reference implementation. The API is not set in stone, by the way. I'm totally open to alternative ones and I'm strongly considering getting rid of ABI encoding and just serializing the data in order. |
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Yeah the spec says 2 words. There are some incidental complexities to storing the value in two state variables in the rust version. The single variable allows using checked arithmetic and typecast in token state update. i'll try and take a closer look at it. |
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@zmanian You may be safe just ignoring the higher-order word. You would have to be hashing ~10^10 GB of data for it to make any difference. It's hacky, but not the end of the world if it saves you a lot of trouble. We just need to make sure all of the implementations behave consistently. |
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It really does save a lot of trouble. I mean nightly does have 128 bit checked arithmetic now... I don't even @vbuterin has enough eth to so 10^10GB on the blockchain :-) |
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@tjade273 What are your numbers on the gas costs of https://github.com/ConsenSys/Project-Alchemy/blob/master/contracts/BLAKE2b/BLAKE2b.sol ? It seems to me that this contract can be heavily optimized. For example the constant could be moved from storage to code / memory (50 gas some time ago, now 200 gas for sload compared to 3 gas for mload / codecopy). This could make it viable to do all that without a precompile. |
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@chriseth I haven't worked on the BLAKE contract since before the gas cost readjustments, so I'm not sure exactly what the costs are. When I last ran it, each run was something like 200k gas. I'm sure I could optimize it more, but the equihash PoW verification requires 2^9 BLAKE compressions, and I though it unlikely that I would be able to get the gas costs below ~6,000. I can take another crack at the optimizations, though and see if I can get the costs significantly lower |
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Is there anything I can do to move this EIP along? I'd really like to reduce barriers to cross-chain interoperation between Ethereum and Zcash, and this would help. (There are other approaches to cross-chain interop, but it isn't yet clear to me that any of the alternatives would be strictly better than this one.) Additionally, making an efficient implementation of BLAKE2 available to Ethereum contracts could help with completely unrelated uses, such as if an Ethereum contract wanted to somehow interoperate with other systems like https://github.com/bramcohen/MerkleSet, or just because BLAKE2 is a highly efficient and secure hash function. I see that the "editor-needs-to-review" label was added. Who is the editor? Thanks! |
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@zookozcash I believe your best bet is probably to create a PR of this EIP. Issues are intended for discussion, which it seems there isn't much of at this point. Once there is no longer any "debate" then a PR that adds the EIP using the template is the next step in the process. I believe the contributing guide was recently updated: https://github.com/ethereum/EIPs#contributing Of course, I could be totally wrong about all this as I'm just a random guy on the internet with no authority, but if I were you the above is what I would do. :) |
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By the way, there are two different motivations for why this EIP should go into Ethereum. The first (dear to my heart) is to facilitate Zcash↔Ethereum interoperation using the "BTCRelay" technique. Basically allowing Ethereum contracts to "see into" the Zcash blockchain! This is already possible, but it is very slow and expensive without this precompile. But I want to emphasize that there is another independent reason for this EIP, which is that BLAKE2 is just a more efficient and more widely used hash function than SHA-3, and this EIP could allow Ethereum contracts to efficiently interoperate with data generated by the growing number of BLAKE2-using data generators out there. I was reminded of this latter fact when reading this blog post by the estimable Adam Langley “Maybe Skip SHA-3” and the ensuing discussions on hackernews and reddit. There appears to be a growing consensus among cryptographers that SHA-3 is not a great fit for most purposes and is not likely to become widely used. Even the authors of SHA-3 seem to be advocating not for adoption of SHA-3, but for adoption of newer, more efficient variants of SHA-3. But everyone agrees that BLAKE2 is efficient, secure, and widely used. By the way, you might enjoy this nice history of hash functions: https://z.cash/technology/history-of-hash-function-attacks.html |
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Thanks a lot for the great feedback. This is definitely making me consider BLAKE2 support much more strongly. |
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The ipfs team is working towards switching our default hash function to blake2b-256, on the grounds of making future integrations much easier, i'm definitely in support of this |
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@tjade273 if it is already ABI encoded, why not have two functions: It may also make sense considering to make the I assume the code using this would either go for Blake2b or Blake2s and wouldn't really switch between them, it would mean cheaper execution as the number of parameters for ABI encoding is lower and uses less memory as well. The downside is of course if the |
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I'm tentatively in favour of this, but I'm not so sure about having a precompile accept ABI-encoded data. Reasons being:
Furthermore, ABI-encoding is imo not fool-proof. It's possible to e.g. point two dynamic arrays to use the same data, or point the data-part to wrap around back to the start of the argument-field. TLDR; I'd rather not have ABI-parsing as part of consensus. |
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@holiman I think it is certainly possible defining a restricted set of ABI encoding supported by this precompile the same way as the data format is described for every other precompile. |
* Brought issue ethereum#152 into the repo as a draft EIP. Thanks @tjade273! * Make the draft EIP consistent with the template Also added myself as an author * Break backwards compatibility into its own section * Added notes about the in-progress implementation Should have a working geth precompile and initial benchmarks shortly * Specify EIP-2046 as a requirement While 2046's cheaper precompile contract calls aren't a requirement for this EIP's implementation, shipping this precompile without EIP-2046 would make the F function expensive for some of the motivating usecases. * Don't use ABI encoding for precompile Replace the existing ABI encoding interface to the BLAKE2b `F` precompile with a loosely pack struct that's `staticcall`-friendly. H/t to @pdyraga for putting together the interface! * Add @pdyraga to the EIP authors. * Remove less relevant EIP rationale Let's not relitigate precompiles, WASM, etc in thie EIP :) * Use 0x09 as the precompile address If a conflicting EIP is moving forward the EIP editor can assign a new address * Choosing an EIP number Contributing docs suggest EIPs be named `eip-draft-with-a-title` until an editor has been assigned, but discussing this work off-platform without a number is a problem. Assigning 152 as the issue number where the `F` precompile was originally raised (ethereum#152) * Add a missing colon Thanks @axic 🙌 * Spelling updates * Add @MadeofTin to the authors list * Prefer the original issue for discussion * Clarify the precompile's initial implementation * Make the precompile return value clear * Clean up references wording * More rationale around this BLAKE2b approach * Fix a couple misspellings * Updated the interface for F precompile - F precompile accepts now `abi.encodePacked` parameters taking exactly 213 bytes. This is safer and does not require left-padding data - `rounds` parameter is now the first one as the gas cost depends only on this parameter * Updated gas cost section proposing GFROUND=1 * Detailed benchmarks moved to appendix section * Benchmark stats are compared against ecRecover as a baseline * Clarification: f parameter is true if it is nonzero This rule is compatible with Solidity for boolean. * Avoid referring to abi.encodePacked The specification should not be Solidity-specific. Instead of referring to abi.encodePacked we now just say "tightly encoded". * Fixed incorrect link "specified in the RFC" linked to the geth PR for F precompile instead of linking to the BLAKE2b RFC. * Shortened the description about when parameter f is considered as true * Minor grammar improvement * Updated information about endianness of F precompile inputs BLAKE2b is consistently little-endian. abi.encodePacked encodes each of its arguments in big-endian order. We need to be clear which parameters should go as little-endian (h, m, t) and which parameters should go as big-endian (rounds, f). * Strict validation of f parameter * Initial test vectors for F precompile Test cases covered: - input length too short - input length too long - malformed f flag encoding - correct input, test vector from BLAKE2b RFC, Appendix A * Test vector for a non-final round * Test vector for the maximum number of rounds * Test vector for a single round * Added test vector for empty input * The final block indicator (8-bit word) does not have endianness * Clarify state vector encoding does not change in the output * Put too short input test vector next to empty input test vector * Added test vector for zero-rounds BLAKE2b case
* Brought issue ethereum#152 into the repo as a draft EIP. Thanks @tjade273! * Make the draft EIP consistent with the template Also added myself as an author * Break backwards compatibility into its own section * Added notes about the in-progress implementation Should have a working geth precompile and initial benchmarks shortly * Specify EIP-2046 as a requirement While 2046's cheaper precompile contract calls aren't a requirement for this EIP's implementation, shipping this precompile without EIP-2046 would make the F function expensive for some of the motivating usecases. * Don't use ABI encoding for precompile Replace the existing ABI encoding interface to the BLAKE2b `F` precompile with a loosely pack struct that's `staticcall`-friendly. H/t to @pdyraga for putting together the interface! * Add @pdyraga to the EIP authors. * Remove less relevant EIP rationale Let's not relitigate precompiles, WASM, etc in thie EIP :) * Use 0x09 as the precompile address If a conflicting EIP is moving forward the EIP editor can assign a new address * Choosing an EIP number Contributing docs suggest EIPs be named `eip-draft-with-a-title` until an editor has been assigned, but discussing this work off-platform without a number is a problem. Assigning 152 as the issue number where the `F` precompile was originally raised (ethereum#152) * Add a missing colon Thanks @axic 🙌 * Spelling updates * Add @MadeofTin to the authors list * Prefer the original issue for discussion * Clarify the precompile's initial implementation * Make the precompile return value clear * Clean up references wording * More rationale around this BLAKE2b approach * Fix a couple misspellings * Updated the interface for F precompile - F precompile accepts now `abi.encodePacked` parameters taking exactly 213 bytes. This is safer and does not require left-padding data - `rounds` parameter is now the first one as the gas cost depends only on this parameter * Updated gas cost section proposing GFROUND=1 * Detailed benchmarks moved to appendix section * Benchmark stats are compared against ecRecover as a baseline * Clarification: f parameter is true if it is nonzero This rule is compatible with Solidity for boolean. * Avoid referring to abi.encodePacked The specification should not be Solidity-specific. Instead of referring to abi.encodePacked we now just say "tightly encoded". * Fixed incorrect link "specified in the RFC" linked to the geth PR for F precompile instead of linking to the BLAKE2b RFC. * Shortened the description about when parameter f is considered as true * Minor grammar improvement * Updated information about endianness of F precompile inputs BLAKE2b is consistently little-endian. abi.encodePacked encodes each of its arguments in big-endian order. We need to be clear which parameters should go as little-endian (h, m, t) and which parameters should go as big-endian (rounds, f). * Strict validation of f parameter * Initial test vectors for F precompile Test cases covered: - input length too short - input length too long - malformed f flag encoding - correct input, test vector from BLAKE2b RFC, Appendix A * Test vector for a non-final round * Test vector for the maximum number of rounds * Test vector for a single round * Added test vector for empty input * The final block indicator (8-bit word) does not have endianness * Clarify state vector encoding does not change in the output * Put too short input test vector next to empty input test vector * Added test vector for zero-rounds BLAKE2b case
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Here is my complete review of the EIP for the last call ending today. Just one item, otherwise everything looks great. Does not require 2046The metadata shows a dependency on EIP-2046. But in-text there is no such reference. Quick fix --> #2420 |
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What use cases do people have in mind for this? Is anyone working on an atomic swap between zcash and eth and eth assets? I don’t really understand the motivation of now including this 3 year old proposal |
* Brought issue ethereum#152 into the repo as a draft EIP. Thanks @tjade273! * Make the draft EIP consistent with the template Also added myself as an author * Break backwards compatibility into its own section * Added notes about the in-progress implementation Should have a working geth precompile and initial benchmarks shortly * Specify EIP-2046 as a requirement While 2046's cheaper precompile contract calls aren't a requirement for this EIP's implementation, shipping this precompile without EIP-2046 would make the F function expensive for some of the motivating usecases. * Don't use ABI encoding for precompile Replace the existing ABI encoding interface to the BLAKE2b `F` precompile with a loosely pack struct that's `staticcall`-friendly. H/t to @pdyraga for putting together the interface! * Add @pdyraga to the EIP authors. * Remove less relevant EIP rationale Let's not relitigate precompiles, WASM, etc in thie EIP :) * Use 0x09 as the precompile address If a conflicting EIP is moving forward the EIP editor can assign a new address * Choosing an EIP number Contributing docs suggest EIPs be named `eip-draft-with-a-title` until an editor has been assigned, but discussing this work off-platform without a number is a problem. Assigning 152 as the issue number where the `F` precompile was originally raised (ethereum#152) * Add a missing colon Thanks @axic 🙌 * Spelling updates * Add @MadeofTin to the authors list * Prefer the original issue for discussion * Clarify the precompile's initial implementation * Make the precompile return value clear * Clean up references wording * More rationale around this BLAKE2b approach * Fix a couple misspellings * Updated the interface for F precompile - F precompile accepts now `abi.encodePacked` parameters taking exactly 213 bytes. This is safer and does not require left-padding data - `rounds` parameter is now the first one as the gas cost depends only on this parameter * Updated gas cost section proposing GFROUND=1 * Detailed benchmarks moved to appendix section * Benchmark stats are compared against ecRecover as a baseline * Clarification: f parameter is true if it is nonzero This rule is compatible with Solidity for boolean. * Avoid referring to abi.encodePacked The specification should not be Solidity-specific. Instead of referring to abi.encodePacked we now just say "tightly encoded". * Fixed incorrect link "specified in the RFC" linked to the geth PR for F precompile instead of linking to the BLAKE2b RFC. * Shortened the description about when parameter f is considered as true * Minor grammar improvement * Updated information about endianness of F precompile inputs BLAKE2b is consistently little-endian. abi.encodePacked encodes each of its arguments in big-endian order. We need to be clear which parameters should go as little-endian (h, m, t) and which parameters should go as big-endian (rounds, f). * Strict validation of f parameter * Initial test vectors for F precompile Test cases covered: - input length too short - input length too long - malformed f flag encoding - correct input, test vector from BLAKE2b RFC, Appendix A * Test vector for a non-final round * Test vector for the maximum number of rounds * Test vector for a single round * Added test vector for empty input * The final block indicator (8-bit word) does not have endianness * Clarify state vector encoding does not change in the output * Put too short input test vector next to empty input test vector * Added test vector for zero-rounds BLAKE2b case
* Brought issue ethereum#152 into the repo as a draft EIP. Thanks @tjade273! * Make the draft EIP consistent with the template Also added myself as an author * Break backwards compatibility into its own section * Added notes about the in-progress implementation Should have a working geth precompile and initial benchmarks shortly * Specify EIP-2046 as a requirement While 2046's cheaper precompile contract calls aren't a requirement for this EIP's implementation, shipping this precompile without EIP-2046 would make the F function expensive for some of the motivating usecases. * Don't use ABI encoding for precompile Replace the existing ABI encoding interface to the BLAKE2b `F` precompile with a loosely pack struct that's `staticcall`-friendly. H/t to @pdyraga for putting together the interface! * Add @pdyraga to the EIP authors. * Remove less relevant EIP rationale Let's not relitigate precompiles, WASM, etc in thie EIP :) * Use 0x09 as the precompile address If a conflicting EIP is moving forward the EIP editor can assign a new address * Choosing an EIP number Contributing docs suggest EIPs be named `eip-draft-with-a-title` until an editor has been assigned, but discussing this work off-platform without a number is a problem. Assigning 152 as the issue number where the `F` precompile was originally raised (ethereum#152) * Add a missing colon Thanks @axic 🙌 * Spelling updates * Add @MadeofTin to the authors list * Prefer the original issue for discussion * Clarify the precompile's initial implementation * Make the precompile return value clear * Clean up references wording * More rationale around this BLAKE2b approach * Fix a couple misspellings * Updated the interface for F precompile - F precompile accepts now `abi.encodePacked` parameters taking exactly 213 bytes. This is safer and does not require left-padding data - `rounds` parameter is now the first one as the gas cost depends only on this parameter * Updated gas cost section proposing GFROUND=1 * Detailed benchmarks moved to appendix section * Benchmark stats are compared against ecRecover as a baseline * Clarification: f parameter is true if it is nonzero This rule is compatible with Solidity for boolean. * Avoid referring to abi.encodePacked The specification should not be Solidity-specific. Instead of referring to abi.encodePacked we now just say "tightly encoded". * Fixed incorrect link "specified in the RFC" linked to the geth PR for F precompile instead of linking to the BLAKE2b RFC. * Shortened the description about when parameter f is considered as true * Minor grammar improvement * Updated information about endianness of F precompile inputs BLAKE2b is consistently little-endian. abi.encodePacked encodes each of its arguments in big-endian order. We need to be clear which parameters should go as little-endian (h, m, t) and which parameters should go as big-endian (rounds, f). * Strict validation of f parameter * Initial test vectors for F precompile Test cases covered: - input length too short - input length too long - malformed f flag encoding - correct input, test vector from BLAKE2b RFC, Appendix A * Test vector for a non-final round * Test vector for the maximum number of rounds * Test vector for a single round * Added test vector for empty input * The final block indicator (8-bit word) does not have endianness * Clarify state vector encoding does not change in the output * Put too short input test vector next to empty input test vector * Added test vector for zero-rounds BLAKE2b case
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There has been no activity on this issue for two months. It will be closed in a week if no further activity occurs. If you would like to move this EIP forward, please respond to any outstanding feedback or add a comment indicating that you have addressed all required feedback and are ready for a review. |
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This issue was closed due to inactivity. If you are still pursuing it, feel free to reopen it and respond to any feedback or request a review in a comment. |
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I see the sad sad fate of this issue, but if I opened one to ask about adding precompile support for BLAKE3, how would that go in terms of people being receptive? It's super speedy, and most importantly is tree-based (which lets you do sped-up partial verification of inputs)... My team is going to use it for distributed data storage validation, and we're looking at either doing some horrifyingly janky workarounds, or calling a blake3 solidity impl that currently costs like $60 per call before any hand-done ASM optimizations. If I put in the work to write a PR for this, will there be bandwidth to support it and/or interest in accepting it as an EVM precompile? |
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Wait, did this make it into Istanbul...? |
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Based on https://medium.com/mycrypto/ethereums-istanbul-fork-technical-explanation-48a3aef718b0, I believe it did go into the Istanbul network upgrade. But unfortunately this proposal was only for the BLAKE2b compression function and not the BLAKE2s compression function. If you had the BLAKE2s compression function, then yes, you could have a very efficient implementation of BLAKE3 on Ethereum. BLAKE3 uses the same compression function as BLAKE2s does: https://github.com/BLAKE3-team/BLAKE3-specs/blob/master/blake3.pdf |
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GAH! how difficult would it be to shove an EIP through within 6 months? Right now I’m staring down the barrel of a $60 hash function, and that’s without the major network congestion issues of a bull run. Need blake3 updateability and verified streaming for the thing I’m building, and I’m sure others will as well in the future… |
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2s and 3, two for the price of one… |
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For what it is worth, the BLAKE2b compression function and the BLAKE2s compression function are identical except for the word size (64-bit words for BLAKE2b, 32-bit words for BLAKE2s and BLAKE3) and four constants: ` The G function of BLAKE2s is: (source: https://www.blake2.net/blake2.pdf . See also the specification of the same round function in https://github.com/BLAKE3-team/BLAKE3-specs/blob/master/blake3.pdf — “The round function is the same as in BLAKE2s.”) If we want to support the updateability and verified streaming functionality that you need, the addition of the BLAKE2s compression function would presumably be simplified and de-risked by copying the existing BLAKE2b compression function and changing the four constants. |
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I would love to get at least an “I’ll consider merging this” from an eth core maintainer before I devote significant energy to making this happen, but pending this, I’ll happily do the refactor. |
Update the EIP to the working version from https://github.com/eth-infinitism/account-abstraction/blob/develop/eip/EIPS/eip-4337.md Changes: AA-94 update keccak rules. AA-93 Adding debug RPC APIs for the Bundler to use (ethereum#153) AA 92 simulate execution (ethereum#152) AA 73 unify reputation (ethereum#144) AA-68 rpc calls (ethereum#132) AA-61 rename wallet to account (ethereum#134) AA-69 wallet support for simulation without signing (ethereum#133) AA-70 rename requestId to userOpHash (ethereum#138) AA-67 relax storage rules in opcode banning (ethereum#121) AA-63 remove paymaster stake value from EntryPoint (ethereum#119) AA-51 simpler simulation api, including aggregation AA-60 validate timestamp (ethereum#117) Clarify wallet factory behavior when the wallet already exists (ethereum#118)
Update the EIP to the working version from https://github.com/eth-infinitism/account-abstraction/blob/develop/eip/EIPS/eip-4337.md Changes: AA-94 update keccak rules. AA-93 Adding debug RPC APIs for the Bundler to use (ethereum#153) AA 92 simulate execution (ethereum#152) AA 73 unify reputation (ethereum#144) AA-68 rpc calls (ethereum#132) AA-61 rename wallet to account (ethereum#134) AA-69 wallet support for simulation without signing (ethereum#133) AA-70 rename requestId to userOpHash (ethereum#138) AA-67 relax storage rules in opcode banning (ethereum#121) AA-63 remove paymaster stake value from EntryPoint (ethereum#119) AA-51 simpler simulation api, including aggregation AA-60 validate timestamp (ethereum#117) Clarify wallet factory behavior when the wallet already exists (ethereum#118)
Update the EIP to the working version from https://github.com/eth-infinitism/account-abstraction/blob/develop/eip/EIPS/eip-4337.md Changes: AA-94 update keccak rules. AA-93 Adding debug RPC APIs for the Bundler to use (ethereum#153) AA 92 simulate execution (ethereum#152) AA 73 unify reputation (ethereum#144) AA-68 rpc calls (ethereum#132) AA-61 rename wallet to account (ethereum#134) AA-69 wallet support for simulation without signing (ethereum#133) AA-70 rename requestId to userOpHash (ethereum#138) AA-67 relax storage rules in opcode banning (ethereum#121) AA-63 remove paymaster stake value from EntryPoint (ethereum#119) AA-51 simpler simulation api, including aggregation AA-60 validate timestamp (ethereum#117) Clarify wallet factory behavior when the wallet already exists (ethereum#118)
* Update to latest working version Update the EIP to the working version from https://github.com/eth-infinitism/account-abstraction/blob/develop/eip/EIPS/eip-4337.md Changes: AA-94 update keccak rules. AA-93 Adding debug RPC APIs for the Bundler to use (#153) AA 92 simulate execution (#152) AA 73 unify reputation (#144) AA-68 rpc calls (#132) AA-61 rename wallet to account (#134) AA-69 wallet support for simulation without signing (#133) AA-70 rename requestId to userOpHash (#138) AA-67 relax storage rules in opcode banning (#121) AA-63 remove paymaster stake value from EntryPoint (#119) AA-51 simpler simulation api, including aggregation AA-60 validate timestamp (#117) Clarify wallet factory behavior when the wallet already exists (#118) * lint fixes
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@laudiacay - just stumbled upon this thread! to get the precompile changed, you'd basically need to write up a new EIP, and have it accepted into the next fork. If you'd want to gauge appetite for that, I'd recommend either drafting an EIP or simply opening a thread on https://ethereum-magicians.org/ to discuss the topic! |
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@timbeiko hey! opened a thread with some initial thoughts :D https://ethereum-magicians.org/t/eip-add-precompile-for-blake2s-blake3/12407 Please let me know what I ought to do next! I did some work on hevm around the Berlin hardfork but have never PR'd geth or drafted an EIP. I have the same handle on Github and Telegram, if you'd like to reach out so we can discuss. |
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@laudiacay great! just pinged you on TG :-) |
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Hej |
and others
Title
Abstract
This EIP introduces a new precompiled contract which implements the compression function
Fused in the BLAKE2b cryptographic hashing algorithm, for the purpose of allowing interoperability between the Zcash blockchain and the EVM, and introducing more flexible cryptographic hash primitives to the EVM.Parameters
METROPOLIS_FORK_BLKNUM: TBDGFROUND: TBDSpecification
Adds a precompile at address
0x0000....0dwhich accepts ABI encoded arguments corresponding to the function signaturewhere
h,m,tandfare the current state, the new message, the byte counter and a finalization flag, as defined in RFC 7693, androundsis the number of rounds of mixing to perform (BLAKE2b uses 12, BLAKE2s uses 10).h_newis the updated state of the hash.Each operation will cost
GFROUND * rounds.Motivation
Besides being a useful cryptographic hash function and SHA3 finalist, BLAKE2b allows for efficient verification of the Equihash PoW used in Zcash, making a BTC Relay - style SPV client possible on Ethereum. A single verification of an Equihash PoW verification requires 512 iterations of the hash function, making verification of Zcash block headers prohibitively expensive if a Solidity implementation of BLAKE2b is used.
The BLAKE2b algorithm is highly optimized for 64-bit CPUs, and is faster than MD5 on modern processors.
Interoperability with Zcash could enable contracts like trustless atomic swaps between the chains, which could provide a much needed aspect of privacy to the very public Ethereum blockchain.
Rationale
The most frequent concern with EIPs of this type is that the addition of specific functions at the protocol level is an infringement on Ethereum's "featureless" design. It is true that a more elegant solution to the issue is to simply improve the scalability characteristics of the network so as to make calculating functions requiring millions of gas practical for everyday use. In the meantime, however, I believe that certain operations are worth subsidising via precompiled contracts and there is significant precedent for this, most notably the inclusion of the SHA256 prcompiled contract, which is included largely to allow inter-operation with the Bitcoin blockchain.
Additionally, BLAKE2b is an excellent candidate for precompilation because of the extremely asymetric efficiency which it exhibits. BLAKE2b is heavily optimized for modern 64-bit CPUs, specifically utilizing 24 and 63-bit rotations to allow parallelism through SIMD instructions and little-endian arithmetic. These characteristics provide exceptional speed on native CPUs: 3.08 cycles per byte, or 1 gibibyte per second on an Intel i5.
In contrast, the big-endian 32 byte semantics of the EVM are not conducive to efficient implementation of BLAKE2, and thus the gas cost associated with computing the hash on the EVM is disproportionate to the true cost of computing the function natively.
Implementation of only the core
Fcompression function allows substantial flexibility and extensibility while keeping changes at the protocol level to a minimum. This will allow functions like tree hashing, incremental hashing, and keyed, salted, and personalized hashing as well as variable length digests, none of which are currently available on the EVM.There is very little risk of breaking backwards-compatibility with this EIP, the sole issue being if someone were to build a contract relying on the address at
0x000....0000dbeing empty. Te likelihood of this is low, and should specific instances arise, the address could be chosen to be any arbitrary value, with negligible risk of collision.The text was updated successfully, but these errors were encountered: