Groth16 Multicommits #702
Groth16 Multicommits #702
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constraint/commitment.go
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| res := make([]uint64, len(commitments)) | ||
| for i := range res { | ||
| res[i] = uint64(commitments[i].CommitmentIndex) | ||
| func (c Commitments) CommitmentWireIndexes() []int { |
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maybe evaluate if instead of computing all the index (wires, commited etc) during proving time, it would not be worth it to store these slices in the CommitmentInfo data struct? Particularly to avoid allocations in the prover.
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| if vk.HasCommitment { | ||
| kSum.AddMixed(&proof.Commitment) | ||
| for i := range proof.Commitments { |
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same, my understanding is we probably won't go over comuple of commitments, but if we do, this place might be a good candidate for a batchAddition
backend/groth16/internal/utils.go
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| import "math/big" | ||
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| // DivideByThresholdOrList divides x into two sub-lists. list must be sorted, non-repeating and contain no value less than indexThreshold | ||
| func DivideByThresholdOrList(indexThreshold int, list []int, x []*big.Int) (ltOrInList, gtAndNotInList []*big.Int) { |
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Replaced, but it still allocates a slice of size len(list), which in this application is small.
frontend/cs/r1cs/api.go
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| if t.VID < builder.cs.GetNbPublicVariables() { | ||
| nbPublicCommitted++ | ||
| } else { | ||
| // Cannot commit to a secret variable that has already been committed to |
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out of curiosity; why can't we just continue here and ignore that? Will comitting to a commitment help in anyway?
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Because of how the result of an api.Commit must be usable as a fiat-shamir challenge, it must have a "one-way" dependence on every variable input to this function. However, the way the commitment scheme is verified is Groth16 necessitates that every private variable can be used in one commitment at most. So if it were needed in multiple commitments, the next best thing is to commit to its commitment (commitments to commitments are easy, they're just conventional hashes.)
internal/utils/search.go
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| @@ -0,0 +1,18 @@ | |||
| package utils | |||
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| // BinarySearch attempts to find the target in x. If not found, returns false and the index where the target would be inserted. | |||
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why not use go standard std Find method?
| }) | ||
| } | ||
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| func hollow(c frontend.Circuit) frontend.Circuit { |
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can you document a bit more this file / the functions?
backend/groth16/bls12-377/setup.go
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| commitmentWires := commitmentInfo.CommitmentIndexes() | ||
| privateCommitted := commitmentInfo.GetPrivateCommitted() | ||
| nbPrivateCommittedWires := internal.NbElements(privateCommitted) | ||
| //nbPrivateCommittedWires, privateCommitted, publicAndCommitmentCommitted := |
Equivalent of #668 for Groth16.