Skip to content

chore: Simplify point decoding logic #267

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
garyschulte merged 4 commits into from
Apr 28, 2025
+8 −44
Merged

chore: Simplify point decoding logic #267

Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
8056e46
bump to gnark-0.17.0, only check point on curve once when unmarshalin…
garyschulte Mar 17, 2025
76ac9df
do explicit (duplicate) isOnCurve checks for bls12
garyschulte Apr 25, 2025
259533f
explicit (dupe) isOnCurve checks in eip-196 also
garyschulte Apr 25, 2025
81eadb7
simplify point decoding methods
kevaundray Mar 19, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
52 changes: 8 additions & 44 deletions gnark/gnark-jni/gnark-eip-2537.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -178,10 +178,12 @@ func _blsG1MultiExp(input []byte, nbTasks int) (*bls12381.G1Affine, error) {

// Decode points and scalars
for i := 0; i < exprCount; i++ {
_, err := g1AffineDecodeInSubGroupVal(&g1Points[i], input[i*160:(i*160)+128])
g1, err := g1AffineDecodeInSubGroup(input[i*160 : (i*160)+128])
if err != nil {
return nil, err
}

g1Points[i].Set(g1)
scalars[i].SetBytes(input[(i*160)+128 : (i+1)*160])
}

Expand Down Expand Up @@ -362,10 +364,12 @@ func _blsG2MultiExp(input []byte, nbTasks int) (*bls12381.G2Affine, error) {

// Decode points and scalars
for i := 0; i < exprCount; i++ {
_, err := g2AffineDecodeInSubGroupVal(&g2Points[i], input[i*288:(i*288)+256])
g2Point, err := g2AffineDecodeInSubGroup(input[i*288 : (i*288)+256])
if err != nil {
return nil, err
}

g2Points[i].Set(g2Point)
scalars[i].SetBytes(input[(i*288)+256 : (i+1)*288])
}

Expand Down Expand Up @@ -694,27 +698,11 @@ func hasWrongG2Padding(input []byte) bool {
// Returns the decoded G1 point if successful, or an error if the decoding fails
// or the point is not on the curve or not in the correct subgroup.
func g1AffineDecodeInSubGroup(input []byte) (*bls12381.G1Affine, error) {
var g1 bls12381.G1Affine
return g1AffineDecodeInSubGroupVal(&g1, input)
}
func g1AffineDecodeInSubGroupVal(g1 *bls12381.G1Affine, input []byte) (*bls12381.G1Affine, error) {
if hasWrongG1Padding(input) {
return nil, ErrMalformedPointPadding
}
err := g1.X.SetBytesCanonical(input[16:64])
if err != nil {
return nil, err
}
err = g1.Y.SetBytesCanonical(input[80:128])
g1, err := g1AffineDecodeOnCurve(input)
if err != nil {
return nil, err
}

// do explicit on-curve check first
if !g1.IsOnCurve() {
return nil, ErrPointOnCurveCheckFailed
}

// do explicit subgroup check
if !g1.IsInSubGroup() {
return nil, ErrSubgroupCheckFailed
Expand Down Expand Up @@ -757,34 +745,10 @@ func g1AffineDecodeOnCurve(input []byte) (*bls12381.G1Affine, error) {
// Returns the decoded G2 point if successful, or an error if the decoding fails
// or the point is not on the curve or not in the correct subgroup.
func g2AffineDecodeInSubGroup(input []byte) (*bls12381.G2Affine, error) {
var g2 bls12381.G2Affine
return g2AffineDecodeInSubGroupVal(&g2, input)
}
func g2AffineDecodeInSubGroupVal(g2 *bls12381.G2Affine, input []byte) (*bls12381.G2Affine, error) {
if hasWrongG2Padding(input) {
return nil, ErrMalformedPointPadding
}

err := g2.X.A0.SetBytesCanonical(input[16:64])
if err != nil {
return nil, err
}
err = g2.X.A1.SetBytesCanonical(input[80:128])
if err != nil {
return nil, err
}
err = g2.Y.A0.SetBytesCanonical(input[144:192])
if err != nil {
return nil, err
}
err = g2.Y.A1.SetBytesCanonical(input[208:256])
g2, err := g2AffineDecodeOnCurve(input)
if err != nil {
return nil, err
}
if !g2.IsOnCurve() {
return nil, ErrPointOnCurveCheckFailed
}

// do explicit subgroup check
if !g2.IsInSubGroup() {
return nil, ErrSubgroupCheckFailed
Expand Down
Loading