Create util to verify KZG commitment by generation and comparison (#1042

)

Signed-off-by: litt3 <[email protected]>

api/clients/v2/verification/verification_utils.go

@@ -0,0 +1,59 @@
+package verification
+
+import (
+	"fmt"
+	"github.com/Layr-Labs/eigenda/encoding"
+	"github.com/consensys/gnark-crypto/ecc"
+	"github.com/consensys/gnark-crypto/ecc/bn254"
+
+	"github.com/Layr-Labs/eigenda/encoding/kzg/verifier"
+	"github.com/Layr-Labs/eigenda/encoding/rs"
+)
+
+// GenerateBlobCommitment computes a kzg-bn254 commitment of blob data using SRS
+func GenerateBlobCommitment(
+	kzgVerifier *verifier.Verifier,
+	blob []byte) (*encoding.G1Commitment, error) {
+
+	inputFr, err := rs.ToFrArray(blob)
+	if err != nil {
+		return nil, fmt.Errorf("convert bytes to field elements, %w", err)
+	}
+
+	if len(kzgVerifier.Srs.G1) < len(inputFr) {
+		return nil, fmt.Errorf(
+			"insufficient SRS in memory: have %v, need %v",
+			len(kzgVerifier.Srs.G1),
+			len(inputFr))
+	}
+
+	var commitment bn254.G1Affine
+	_, err = commitment.MultiExp(kzgVerifier.Srs.G1[:len(inputFr)], inputFr, ecc.MultiExpConfig{})
+	if err != nil {
+		return nil, fmt.Errorf("MultiExp: %w", err)
+	}
+
+	return &encoding.G1Commitment{X: commitment.X, Y: commitment.Y}, nil
+}
+
+// GenerateAndCompareBlobCommitment generates the kzg-bn254 commitment of the blob, and compares it with a claimed
+// commitment. An error is returned if there is a problem generating the commitment, or if the comparison fails.
+func GenerateAndCompareBlobCommitment(
+	kzgVerifier *verifier.Verifier,
+	claimedCommitment *encoding.G1Commitment,
+	blobBytes []byte) error {
+
+	computedCommitment, err := GenerateBlobCommitment(kzgVerifier, blobBytes)
+	if err != nil {
+		return fmt.Errorf("compute commitment: %w", err)
+	}
+
+	if claimedCommitment.X.Equal(&computedCommitment.X) &&
+		claimedCommitment.Y.Equal(&computedCommitment.Y) {
+		return nil
+	}
+
+	return fmt.Errorf(
+		"commitment field elements do not match. computed commitment: (x: %x, y: %x), claimed commitment (x: %x, y: %x)",
+		computedCommitment.X, computedCommitment.Y, claimedCommitment.X, claimedCommitment.Y)
+}

api/clients/v2/verification/verification_utils_test.go

@@ -0,0 +1,125 @@
+package verification
+
+import (
+	"github.com/Layr-Labs/eigenda/common/testutils/random"
+	"github.com/Layr-Labs/eigenda/encoding/kzg"
+	"github.com/Layr-Labs/eigenda/encoding/kzg/verifier"
+	"github.com/Layr-Labs/eigenda/encoding/utils/codec"
+	"github.com/stretchr/testify/require"
+	"runtime"
+	"testing"
+)
+
+func getKzgConfig() *kzg.KzgConfig {
+	return &kzg.KzgConfig{
+		G1Path:          "../../../../inabox/resources/kzg/g1.point",
+		G2Path:          "../../../../inabox/resources/kzg/g2.point",
+		G2PowerOf2Path:  "../../../../inabox/resources/kzg/g2.point.powerOf2",
+		CacheDir:        "../../../../inabox/resources/kzg/SRSTables",
+		SRSOrder:        3000,
+		SRSNumberToLoad: 2900,
+		NumWorker:       uint64(runtime.GOMAXPROCS(0)),
+		LoadG2Points:    false,
+	}
+}
+
+// randomlyModifyBytes picks a random byte from the input array, and increments it
+func randomlyModifyBytes(testRandom *random.TestRandom, inputBytes []byte) {
+	indexToModify := testRandom.Intn(len(inputBytes))
+	inputBytes[indexToModify] = inputBytes[indexToModify] + 1
+}
+
+func getRandomPaddedBytes(testRandom *random.TestRandom, count int) []byte {
+	return codec.ConvertByPaddingEmptyByte(testRandom.Bytes(count))
+}
+
+func TestComputeAndCompareKzgCommitmentSuccess(t *testing.T) {
+	testRandom := random.NewTestRandom(t)
+	randomBytes := getRandomPaddedBytes(testRandom, 1000)
+
+	kzgVerifier, err := verifier.NewVerifier(getKzgConfig(), nil)
+	require.NotNil(t, kzgVerifier)
+	require.NoError(t, err)
+
+	commitment, err := GenerateBlobCommitment(kzgVerifier, randomBytes)
+	require.NotNil(t, commitment)
+	require.NoError(t, err)
+
+	// make sure the commitment verifies correctly
+	err = GenerateAndCompareBlobCommitment(
+		kzgVerifier,
+		commitment,
+		randomBytes)
+	require.NoError(t, err)
+}
+
+func TestComputeAndCompareKzgCommitmentFailure(t *testing.T) {
+	testRandom := random.NewTestRandom(t)
+	randomBytes := getRandomPaddedBytes(testRandom, 1000)
+
+	kzgVerifier, err := verifier.NewVerifier(getKzgConfig(), nil)
+	require.NotNil(t, kzgVerifier)
+	require.NoError(t, err)
+
+	commitment, err := GenerateBlobCommitment(kzgVerifier, randomBytes)
+	require.NotNil(t, commitment)
+	require.NoError(t, err)
+
+	// randomly modify the bytes, and make sure the commitment verification fails
+	randomlyModifyBytes(testRandom, randomBytes)
+	err = GenerateAndCompareBlobCommitment(
+		kzgVerifier,
+		commitment,
+		randomBytes)
+	require.NotNil(t, err)
+}
+
+func TestGenerateBlobCommitmentEquality(t *testing.T) {
+	testRandom := random.NewTestRandom(t)
+	randomBytes := getRandomPaddedBytes(testRandom, 1000)
+
+	kzgVerifier, err := verifier.NewVerifier(getKzgConfig(), nil)
+	require.NotNil(t, kzgVerifier)
+	require.NoError(t, err)
+
+	// generate two identical commitments
+	commitment1, err := GenerateBlobCommitment(kzgVerifier, randomBytes)
+	require.NotNil(t, commitment1)
+	require.NoError(t, err)
+	commitment2, err := GenerateBlobCommitment(kzgVerifier, randomBytes)
+	require.NotNil(t, commitment2)
+	require.NoError(t, err)
+
+	// commitments to identical bytes should be equal
+	require.Equal(t, commitment1, commitment2)
+
+	// randomly modify a byte
+	randomlyModifyBytes(testRandom, randomBytes)
+	commitmentA, err := GenerateBlobCommitment(kzgVerifier, randomBytes)
+	require.NotNil(t, commitmentA)
+	require.NoError(t, err)
+
+	// commitments to non-identical bytes should not be equal
+	require.NotEqual(t, commitment1, commitmentA)
+}
+
+func TestGenerateBlobCommitmentTooLong(t *testing.T) {
+	kzgVerifier, err := verifier.NewVerifier(getKzgConfig(), nil)
+	require.NotNil(t, kzgVerifier)
+	require.NoError(t, err)
+
+	// this is the absolute maximum number of bytes we can handle, given how the verifier was configured
+	almostTooLongByteCount := 2900 * 32
+
+	// an array of exactly this size should be fine
+	almostTooLongBytes := make([]byte, almostTooLongByteCount)
+	commitment1, err := GenerateBlobCommitment(kzgVerifier, almostTooLongBytes)
+	require.NotNil(t, commitment1)
+	require.NoError(t, err)
+
+	// but 1 more byte is more than we can handle
+	tooLongBytes := make([]byte, almostTooLongByteCount+1)
+	commitment2, err := GenerateBlobCommitment(kzgVerifier, tooLongBytes)
+	require.Nil(t, commitment2)
+	require.NotNil(t, err)
+}