add wrapper for GT

crypto/bn256/gnark/gt.go

@@ -0,0 +1,66 @@
+package bn256
+
+import (
+	"fmt"
+	"math/big"
+
+	"github.com/consensys/gnark-crypto/ecc/bn254"
+)
+
+// GT is the affine representation of a GT field element.
+//
+// Note: GT is not explicitly used in mainline code.
+// It is needed for fuzzing.
+type GT struct {
+	inner bn254.GT
+}
+
+// Pair compute the optimal Ate pairing between a G1 and
+// G2 element.
+//
+// Note: This method is not explicitly used in mainline code.
+// It is needed for fuzzing. It should also be noted,
+// that the output of this function may not match other
+func Pair(a_ *G1, b_ *G2) *GT {
+
+	a := a_.inner
+	b := b_.inner
+
+	pairingOutput, err := bn254.Pair([]bn254.G1Affine{a}, []bn254.G2Affine{b})
+
+	if err != nil {
+		// Since this method is only called during fuzzing, it is okay to panic here.
+		// We do not return an error to match the interface of the other bn256 libraries.
+		panic(fmt.Sprintf("gnark/bn254 encountered error: %v", err))
+	}
+
+	return &GT{
+		inner: pairingOutput,
+	}
+}
+
+// Unmarshal deserializes `buf` into `g`
+//
+// Note: This method is not explicitly used in mainline code.
+// It is needed for fuzzing.
+func (g *GT) Unmarshal(buf []byte) error {
+	return g.inner.SetBytes(buf)
+}
+
+// Marshal serializes the point into a byte slice.
+//
+// Note: This method is not explicitly used in mainline code.
+// It is needed for fuzzing.
+func (g *GT) Marshal() []byte {
+	bytes := g.inner.Bytes()
+	return bytes[:]
+}
+
+// Exp exponentiates `base` to the power of `exponent`
+//
+// Note: This method is not explicitly used in mainline code.
+// It is needed for fuzzing.
+func (g *GT) Exp(base GT, exponent *big.Int) *GT {
+	g.inner.Exp(base.inner, exponent)
+	return g
+}