fix blob verification precompile

Author: jagdeep sidhu

core/types/data_blob.go

@@ -116,9 +116,16 @@ func (n *NEVMBlob) FromWire(NEVMBlobWire *wire.NEVMBlob) error {
 	if lenBlob > params.FieldElementsPerBlob {
 		return errors.New("Blob too big")
 	}
+	if lenBlob < 1024 {
+		return errors.New("Blob too small")
+	}
+	if lenBlob%32 != 0 {
+		return errors.New("Blob should be a factor of 32")
+	}
 	n.Blob = make([]bls.Fr, params.FieldElementsPerBlob)
+	numElements := lenBlob/32
 	var inputPoint [32]byte
-	for i := 0; i < lenBlob; i++ {
+	for i := 0; i < numElements; i++ {
 		copy(inputPoint[:32], NEVMBlobWire.Blob[i*32:(i+1)*32])
 		ok := bls.FrFrom32(&n.Blob[i], inputPoint)
 		if ok != true {
@@ -135,9 +142,16 @@ func (n *NEVMBlob) FromBytes(blob []byte) error {
 	if lenBlob > params.FieldElementsPerBlob {
 		return errors.New("Blob too big")
 	}
+	if lenBlob < 1024 {
+		return errors.New("Blob too small")
+	}
+	if lenBlob%32 != 0 {
+		return errors.New("Blob should be a factor of 32")
+	}
 	n.Blob = make([]bls.Fr, params.FieldElementsPerBlob)
+	numElements := lenBlob/32
 	var inputPoint [32]byte
-	for i := 0; i < lenBlob; i++ {
+	for i := 0; i < numElements; i++ {
 		copy(inputPoint[:32], blob[i*32:(i+1)*32])
 		ok := bls.FrFrom32(&n.Blob[i], inputPoint)
 		if ok != true {

core/vm/contracts.go

@@ -1094,12 +1094,12 @@ type blobVerification struct{}
 
 // RequiredGas returns the gas required to execute the pre-compiled contract.
 func (c *blobVerification) RequiredGas(input []byte) uint64 {
-	// 4096 (4096*32) is base gas (BlobVerificationGas), anything above should scale up the cost
+	// 4096 (4096*32 + 32) is base gas (BlobVerificationGas), anything above should scale up the cost
 	return params.BlobVerificationGas * (uint64(len(input))/131104)
 }
 
 func (c *blobVerification) Run(input []byte, interpreter *EVMInterpreter) ([]byte, error) {
-	if len(input) != 32+(32*params.FieldElementsPerBlob) {
+	if len(input) < 32+(32*32) || len(input) > 32+(32*params.FieldElementsPerBlob) {
 		return nil, errBlobVerificationInputLength
 	}
 
@@ -1110,10 +1110,14 @@ func (c *blobVerification) Run(input []byte, interpreter *EVMInterpreter) ([]byt
 	}
 
 	input = input[32:] // skip forward to the input points
-
+	lenInput := len(input)
+	if (lenInput%32) != 0 {
+		return nil, errInvalidChunk
+	}
+	numElements := lenInput/32
 	inputPoints := make([]bls.Fr, params.FieldElementsPerBlob, params.FieldElementsPerBlob)
 	var inputPoint [32]byte
-	for i := 0; i < params.FieldElementsPerBlob; i++ {
+	for i := 0; i < numElements; i++ {
 		copy(inputPoint[:32], input[i*32:(i+1)*32])
 		ok := bls.FrFrom32(&inputPoints[i], inputPoint)
 		if ok != true {

tests/kzg_bench_test.go

@@ -14,7 +14,7 @@ import (
 
 func randomBlob() []bls.Fr {
 	blob := make([]bls.Fr, params.FieldElementsPerBlob)
-	for i := 0; i < len(blob); i++ {
+	for i := 0; i < params.FieldElementsPerBlob; i++ {
 		blob[i] = *bls.RandomFr()
 	}
 	return blob
@@ -27,7 +27,7 @@ func BenchmarkBlobToKzg(b *testing.B) {
 		kzg.BlobToKzg(blob)
 	}
 }
-func BenchmarkVerify(b *testing.B) {
+func BenchmarkVerifyBlob(b *testing.B) {
 	var blobs types.NEVMBlobs
 	blobs.Blobs = make([]*types.NEVMBlob, 32)
 	for i := 0; i < 32; i++ {