mirror of https://github.com/ethereum/go-ethereum
crypto, tests/fuzzers: add gnark bn254 precompile methods for fuzzing (#30585)
Makes the gnark precompile methods more amenable to fuzzingpull/30666/head
kevaundray
1 month ago
committed by
GitHub
parent
459bb4a647
commit
74461aecf6
@ -0,0 +1,51 @@ |
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package bn256 |
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import ( |
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"math/big" |
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"github.com/consensys/gnark-crypto/ecc/bn254" |
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) |
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// G1 is the affine representation of a G1 group element.
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//
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// Since this code is used for precompiles, using Jacobian
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// points are not beneficial because there are no intermediate
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// points to allow us to save on inversions.
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//
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// Note: We also use this struct so that we can conform to the existing API
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// that the precompiles want.
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type G1 struct { |
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inner bn254.G1Affine |
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} |
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// Add adds `a` and `b` together, storing the result in `g`
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func (g *G1) Add(a, b *G1) { |
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g.inner.Add(&a.inner, &b.inner) |
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} |
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// ScalarMult computes the scalar multiplication between `a` and
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// `scalar`, storing the result in `g`
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func (g *G1) ScalarMult(a *G1, scalar *big.Int) { |
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g.inner.ScalarMultiplication(&a.inner, scalar) |
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} |
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// Unmarshal deserializes `buf` into `g`
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//
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// Note: whether the deserialization is of a compressed
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// or an uncompressed point, is encoded in the bytes.
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//
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// For our purpose, the point will always be serialized
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// as uncompressed, ie 64 bytes.
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//
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// This method also checks whether the point is on the
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// curve and in the prime order subgroup.
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func (g *G1) Unmarshal(buf []byte) (int, error) { |
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return g.inner.SetBytes(buf) |
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} |
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// Marshal serializes the point into a byte slice.
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//
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// Note: The point is serialized as uncompressed.
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func (p *G1) Marshal() []byte { |
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return p.inner.Marshal() |
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} |
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@ -0,0 +1,38 @@ |
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package bn256 |
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import ( |
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"github.com/consensys/gnark-crypto/ecc/bn254" |
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) |
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// G2 is the affine representation of a G2 group element.
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//
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// Since this code is used for precompiles, using Jacobian
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// points are not beneficial because there are no intermediate
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// points and G2 in particular is only used for the pairing input.
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//
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// Note: We also use this struct so that we can conform to the existing API
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// that the precompiles want.
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type G2 struct { |
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inner bn254.G2Affine |
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} |
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// Unmarshal deserializes `buf` into `g`
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//
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// Note: whether the deserialization is of a compressed
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// or an uncompressed point, is encoded in the bytes.
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//
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// For our purpose, the point will always be serialized
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// as uncompressed, ie 128 bytes.
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//
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// This method also checks whether the point is on the
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// curve and in the prime order subgroup.
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func (g *G2) Unmarshal(buf []byte) (int, error) { |
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return g.inner.SetBytes(buf) |
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} |
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// Marshal serializes the point into a byte slice.
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//
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// Note: The point is serialized as uncompressed.
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func (g *G2) Marshal() []byte { |
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return g.inner.Marshal() |
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} |
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@ -0,0 +1,65 @@ |
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package bn256 |
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import ( |
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"fmt" |
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"math/big" |
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"github.com/consensys/gnark-crypto/ecc/bn254" |
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) |
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// GT is the affine representation of a GT field element.
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//
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// Note: GT is not explicitly used in mainline code.
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// It is needed for fuzzing.
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type GT struct { |
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inner bn254.GT |
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} |
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// Pair compute the optimal Ate pairing between a G1 and
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// G2 element.
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//
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// Note: This method is not explicitly used in mainline code.
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// It is needed for fuzzing. It should also be noted,
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// that the output of this function may not match other
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func Pair(a_ *G1, b_ *G2) *GT { |
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a := a_.inner |
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b := b_.inner |
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pairingOutput, err := bn254.Pair([]bn254.G1Affine{a}, []bn254.G2Affine{b}) |
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if err != nil { |
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// Since this method is only called during fuzzing, it is okay to panic here.
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// We do not return an error to match the interface of the other bn256 libraries.
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panic(fmt.Sprintf("gnark/bn254 encountered error: %v", err)) |
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} |
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return >{ |
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inner: pairingOutput, |
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} |
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} |
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// Unmarshal deserializes `buf` into `g`
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//
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// Note: This method is not explicitly used in mainline code.
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// It is needed for fuzzing.
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func (g *GT) Unmarshal(buf []byte) error { |
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return g.inner.SetBytes(buf) |
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} |
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// Marshal serializes the point into a byte slice.
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//
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// Note: This method is not explicitly used in mainline code.
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// It is needed for fuzzing.
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func (g *GT) Marshal() []byte { |
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bytes := g.inner.Bytes() |
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return bytes[:] |
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} |
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// Exp raises `base` to the power of `exponent`
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//
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// Note: This method is not explicitly used in mainline code.
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// It is needed for fuzzing.
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func (g *GT) Exp(base GT, exponent *big.Int) *GT { |
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g.inner.Exp(base.inner, exponent) |
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return g |
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} |
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@ -0,0 +1,73 @@ |
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package bn256 |
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import ( |
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"github.com/consensys/gnark-crypto/ecc/bn254" |
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) |
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// Computes the following relation: ∏ᵢ e(Pᵢ, Qᵢ) =? 1
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//
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// To explain why gnark returns a (bool, error):
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//
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// - If the function `e` does not return a result then internally
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// an error is returned.
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// - If `e` returns a result, then error will be nil,
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// but if this value is not `1` then the boolean value will be false
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//
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// We therefore check for an error, and return false if its non-nil and
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// then return the value of the boolean if not.
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func PairingCheck(a_ []*G1, b_ []*G2) bool { |
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a := getInnerG1s(a_) |
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b := getInnerG2s(b_) |
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// Assume that len(a) == len(b)
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//
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// The pairing function will return
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// false, if this is not the case.
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size := len(a) |
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// Check if input is empty -- gnark will
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// return false on an empty input, however
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// the ossified behavior is to return true
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// on an empty input, so we add this if statement.
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if size == 0 { |
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return true |
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} |
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ok, err := bn254.PairingCheck(a, b) |
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if err != nil { |
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return false |
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} |
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return ok |
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} |
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// getInnerG1s gets the inner gnark G1 elements.
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//
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// These methods are used for two reasons:
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//
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// - We use a new type `G1`, so we need to convert from
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// []*G1 to []*bn254.G1Affine
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// - The gnark API accepts slices of values and not slices of
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// pointers to values, so we need to return []bn254.G1Affine
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// instead of []*bn254.G1Affine.
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func getInnerG1s(pointerSlice []*G1) []bn254.G1Affine { |
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gnarkValues := make([]bn254.G1Affine, 0, len(pointerSlice)) |
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for _, ptr := range pointerSlice { |
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if ptr != nil { |
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gnarkValues = append(gnarkValues, ptr.inner) |
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} |
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} |
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return gnarkValues |
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} |
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// getInnerG2s gets the inner gnark G2 elements.
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//
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// The rationale for this method is the same as `getInnerG1s`.
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func getInnerG2s(pointerSlice []*G2) []bn254.G2Affine { |
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gnarkValues := make([]bn254.G2Affine, 0, len(pointerSlice)) |
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for _, ptr := range pointerSlice { |
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if ptr != nil { |
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gnarkValues = append(gnarkValues, ptr.inner) |
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} |
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} |
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return gnarkValues |
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} |
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