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Start implementing a bytes API with appropriate interfaces
Also fix incorrect hash type (Keccac -> Sha256) when computing versioned hash.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,122 @@ | ||
| package kzg | ||
|
|
||
| import ( | ||
| "crypto/sha256" | ||
| "errors" | ||
| "fmt" | ||
|
|
||
| "github.com/ethereum/go-ethereum/params" | ||
| "github.com/protolambda/go-kzg/bls" | ||
| ) | ||
|
|
||
| // The custom types from EIP-4844 consensus spec: | ||
| // https://github.com/ethereum/consensus-specs/blob/dev/specs/eip4844/polynomial-commitments.md#custom-types | ||
| type KZGCommitment [48]byte | ||
| type KZGProof [48]byte | ||
| type VersionedHash [32]byte | ||
|
|
||
| type BlobSequence interface { | ||
| Len() int | ||
| At(int) Blob | ||
| } | ||
|
|
||
| type Blob interface { | ||
| Len() int | ||
| At(int) [32]byte | ||
| } | ||
|
|
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| type KZGCommitmentSequence interface { | ||
| Len() int | ||
| At(int) KZGCommitment | ||
| } | ||
|
|
||
| // PointEvaluationPrecompile implements point_evaluation_precompile from EIP-4844 | ||
| func PointEvaluationPrecompile(input []byte) ([]byte, error) { | ||
| if len(input) != 192 { | ||
| return nil, errors.New("invalid input length") | ||
| } | ||
|
|
||
| // versioned hash: first 32 bytes | ||
| var versionedHash [32]byte | ||
| copy(versionedHash[:], input[:32]) | ||
|
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||
| var x, y [32]byte | ||
| // Evaluation point: next 32 bytes | ||
| copy(x[:], input[32:64]) | ||
| // Expected output: next 32 bytes | ||
| copy(y[:], input[64:96]) | ||
|
|
||
| // successfully converting x and y to bls.Fr confirms they are < MODULUS per the spec | ||
| var xFr, yFr bls.Fr | ||
| ok := bls.FrFrom32(&xFr, x) | ||
| if !ok { | ||
| return nil, errors.New("invalid evaluation point") | ||
| } | ||
| ok = bls.FrFrom32(&yFr, y) | ||
| if !ok { | ||
| return nil, errors.New("invalid expected output") | ||
| } | ||
|
|
||
| // input kzg point: next 48 bytes | ||
| var dataKZG [48]byte | ||
| copy(dataKZG[:], input[96:144]) | ||
| if KZGToVersionedHash(KZGCommitment(dataKZG)) != VersionedHash(versionedHash) { | ||
| return nil, errors.New("mismatched versioned hash") | ||
| } | ||
|
|
||
| // Quotient kzg: next 48 bytes | ||
| var quotientKZG [48]byte | ||
| copy(quotientKZG[:], input[144:192]) | ||
|
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| ok, err := VerifyKZGProof(KZGCommitment(dataKZG), &xFr, &yFr, KZGProof(quotientKZG)) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("verify_kzg_proof error: %v", err) | ||
| } | ||
| if !ok { | ||
| return nil, errors.New("failed to verify kzg proof") | ||
| } | ||
| return []byte{}, nil | ||
| } | ||
|
|
||
| // KZGToVersionedHash implements kzg_to_versioned_hash from EIP-4844 | ||
| func KZGToVersionedHash(kzg KZGCommitment) VersionedHash { | ||
| h := sha256.Sum256(kzg[:]) | ||
| h[0] = params.BlobCommitmentVersionKZG | ||
| return VersionedHash([32]byte(h)) | ||
| } | ||
|
|
||
| // BlobToKZGCommitment implements blob_to_kzg_commitment from the EIP-4844 consensus spec: | ||
| // https://github.com/ethereum/consensus-specs/blob/dev/specs/eip4844/polynomial-commitments.md#blob_to_kzg_commitment | ||
| func BlobToKZGCommitment(blob Blob) (KZGCommitment, bool) { | ||
| poly, ok := BlobToPolynomial(blob) | ||
| if !ok { | ||
| return KZGCommitment{}, false | ||
| } | ||
| return PolynomialToKZGCommitment(poly), true | ||
| } | ||
|
|
||
| // VerifyAggregateKZGProof implements verify_aggregate_kzg_proof from the EIP-4844 consensus spec: | ||
| // https://github.com/ethereum/consensus-specs/blob/dev/specs/eip4844/polynomial-commitments.md#verify_aggregate_kzg_proof | ||
| func VerifyAggregateKZGProof(blobs BlobSequence, expectedKZGCommitments KZGCommitmentSequence, kzgAggregatedProof KZGProof) (bool, error) { | ||
| polynomials, ok := BlobsToPolynomials(blobs) | ||
| if !ok { | ||
| return false, errors.New("could not convert blobs to polynomials") | ||
| } | ||
| aggregatedPoly, aggregatedPolyCommitment, evaluationChallenge, err := | ||
| ComputeAggregatedPolyAndCommitment(polynomials, expectedKZGCommitments) | ||
| if err != nil { | ||
| return false, err | ||
| } | ||
| y := EvaluatePolynomialInEvaluationForm(aggregatedPoly, evaluationChallenge) | ||
| return VerifyKZGProof(aggregatedPolyCommitment, evaluationChallenge, y, kzgAggregatedProof) | ||
| } | ||
|
|
||
| // ComputeAggregateKZGProof implements compute_aggregate_kzg_proof from the EIP-4844 consensus spec: | ||
| // https://github.com/ethereum/consensus-specs/blob/dev/specs/eip4844/polynomial-commitments.md#compute_aggregate_kzg_proof | ||
| func ComputeAggregateKZGProof(blobs BlobSequence) (KZGProof, error) { | ||
| polynomials, ok := BlobsToPolynomials(blobs) | ||
| if !ok { | ||
| return KZGProof{}, errors.New("could not convert blobs to polynomials") | ||
| } | ||
| return ComputeAggregateKZGProofFromPolynomials(polynomials) | ||
| } |
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