diff --git a/backend/groth16/bn254/mpcsetup/marshal_test.go b/backend/groth16/bn254/mpcsetup/marshal_test.go
deleted file mode 100644
index adbfc3fe0..000000000
--- a/backend/groth16/bn254/mpcsetup/marshal_test.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// Copyright 2020-2024 Consensys Software Inc.
-// Licensed under the Apache License, Version 2.0. See the LICENSE file for details.
-
-// Code generated by gnark DO NOT EDIT
-
-package mpcsetup
-
-/* TODO bring this back
-func TestContributionSerialization(t *testing.T) {
-	if testing.Short() {
-		t.Skip("skipping test in short mode.")
-	}
-	assert := require.New(t)
-
-	// Phase 1
-	var srs1 Phase1
-	srs1.Initialize(1 << 9)
-	srs1.Contribute()
-
-	assert.NoError(gnarkio.RoundTripCheck(&srs1, func() interface{} { return new(Phase1) }))
-
-	var myCircuit Circuit
-	ccs, err := frontend.Compile(curve.ID.ScalarField(), r1cs.NewBuilder, &myCircuit)
-	assert.NoError(err)
-
-	r1cs := ccs.(*cs.R1CS)
-
-	// Phase 2
-	srs2, _ := InitPhase2(r1cs, &srs1)
-	srs2.Contribute()
-
-	assert.NoError(gnarkio.RoundTripCheck(&srs2, func() interface{} { return new(Phase2) }))
-}
-*/
diff --git a/backend/groth16/bn254/mpcsetup/phase2.go b/backend/groth16/bn254/mpcsetup/phase2.go
index 5b64068c4..957a3f70a 100644
--- a/backend/groth16/bn254/mpcsetup/phase2.go
+++ b/backend/groth16/bn254/mpcsetup/phase2.go
@@ -34,7 +34,7 @@ type Phase2Evaluations struct { // TODO @Tabaie rename
 		B []curve.G2Affine // B are the right coefficient polynomials for each witness element, evaluated at τ
 	}
 	PublicAndCommitmentCommitted [][]int
-	NbConstraints                uint64
+	NbConstraints                uint64 // TODO unnecessary. len(Z) has that information (domain size)
 }
 
 type Phase2 struct {
@@ -348,6 +348,7 @@ func VerifyPhase2(r1cs *cs.R1CS, commons *SrsCommons, beaconChallenge []byte, c
 func (p *Phase2) hash() []byte {
 	sha := sha256.New()
 	p.WriteTo(sha)
+	sha.Write(p.Challenge)
 	return sha.Sum(nil)
 }
 
diff --git a/backend/groth16/bn254/mpcsetup/setup.go b/backend/groth16/bn254/mpcsetup/setup.go
index 739438c29..715ac7fc3 100644
--- a/backend/groth16/bn254/mpcsetup/setup.go
+++ b/backend/groth16/bn254/mpcsetup/setup.go
@@ -36,7 +36,7 @@ func (p *Phase2) Seal(commons *SrsCommons, evals *Phase2Evaluations, beaconChall
 	)
 
 	// Initialize PK
-	pk.Domain = *fft.NewDomain(evals.NbConstraints)
+	pk.Domain = *fft.NewDomain(evals.NbConstraints) // TODO @Tabaie replace with len(Z)+1
 	pk.G1.Alpha.Set(&commons.G1.AlphaTau[0])
 	pk.G1.Beta.Set(&commons.G1.BetaTau[0])
 	pk.G1.Delta.Set(&p.Parameters.G1.Delta)
diff --git a/backend/groth16/bn254/mpcsetup/setup_test.go b/backend/groth16/bn254/mpcsetup/setup_test.go
index 5760d471b..d5714bca9 100644
--- a/backend/groth16/bn254/mpcsetup/setup_test.go
+++ b/backend/groth16/bn254/mpcsetup/setup_test.go
@@ -12,6 +12,7 @@ import (
 	"github.com/consensys/gnark-crypto/ecc/bn254/fr"
 	cs "github.com/consensys/gnark/constraint/bn254"
 	"io"
+	"slices"
 	"sync"
 	"testing"
 
@@ -50,7 +51,7 @@ func testAll(t *testing.T, nbContributionsPhase1, nbContributionsPhase2 int) {
 		bb.Reset()
 		_, err := v.WriteTo(&bb)
 		assert.NoError(err)
-		return bb.Bytes()
+		return slices.Clone(bb.Bytes())
 	}
 	deserialize := func(v io.ReaderFrom, b []byte) {
 		n, err := v.ReadFrom(bytes.NewReader(b))
diff --git a/backend/groth16/bn254/mpcsetup/unit_test.go b/backend/groth16/bn254/mpcsetup/unit_test.go
index d8c0f0011..35cae3d23 100644
--- a/backend/groth16/bn254/mpcsetup/unit_test.go
+++ b/backend/groth16/bn254/mpcsetup/unit_test.go
@@ -8,6 +8,11 @@ import (
 	"github.com/consensys/gnark-crypto/ecc/bn254/fr"
 	"github.com/consensys/gnark/backend/groth16"
 	groth16Impl "github.com/consensys/gnark/backend/groth16/bn254"
+	"github.com/consensys/gnark/constraint"
+	cs "github.com/consensys/gnark/constraint/bn254"
+	"github.com/consensys/gnark/frontend"
+	"github.com/consensys/gnark/frontend/cs/r1cs"
+	gnarkio "github.com/consensys/gnark/io"
 	"github.com/stretchr/testify/require"
 	"math/big"
 	"slices"
@@ -106,7 +111,7 @@ func TestNoContributors(t *testing.T) {
 }
 
 func TestOnePhase1Contribute(t *testing.T) {
-	testAll(t, 1, 0)
+	testAll(t, 2, 0)
 }
 
 func TestUpdateCheck(t *testing.T) {
@@ -416,3 +421,97 @@ func TestLinearCombinationsG2(t *testing.T) {
 		frs(1, 3, 9, 27, 81),
 	)
 }
+
+func ones(N int) []fr.Element {
+	res := make([]fr.Element, N)
+	for i := range res {
+		res[i].SetOne()
+	}
+	return res
+}
+
+func frs(x ...int) []fr.Element {
+	res := make([]fr.Element, len(x))
+	for i := range res {
+		res[i].SetInt64(int64(x[i]))
+	}
+	return res
+}
+
+func TestSerialization(t *testing.T) {
+
+	testRoundtrip := func(_cs constraint.ConstraintSystem) {
+		var (
+			p1 Phase1
+			p2 Phase2
+		)
+		p1.Initialize(ecc.NextPowerOfTwo(uint64(_cs.GetNbConstraints())))
+		commons := p1.Seal([]byte("beacon 1"))
+
+		p2.Initialize(_cs.(*cs.R1CS), &commons)
+		p2.Contribute()
+		require.NoError(t, gnarkio.RoundTripCheck(&p2, func() interface{} { return new(Phase2) }))
+	}
+
+	/*var p Phase2
+	const b64 = "AACNaN0mCOtKUAD0aEvRP0h7pXctaB+w5Mwsb+skm2yDuPzlwTs+qCFf/3INR+fP/lHY6BLnqXyBjAIgCoPxOcSIEG0tcty/TAiaCN3lHCRacU+upLP+WpngByrrxbN9KrhmQLY3mhOHaV5Jo3W9pI2lTpLK9ZjkQpYKd92YCRKkJ9LyX3wqeYR4jQFf1mxtfJSNgluSZUUn3AoUSDmvh8m87TRh/JRcRZnq40BgnhkJ5nHs9siMSmhWGFjGgW/mOqpyrFoZEoK2rP+AT6ylkNGYxMmOBUj0meoeI2FB7RDqcuSxQOL1XK+Pm1dhxND33cykwpTF4oCrqQzSonxQGn+wFNzaYREOmkjCS9i12NbpXNyN2b9YpmujAL/GSD5LAwKNaN0mCOtKUAD0aEvRP0h7pXctaB+w5Mwsb+skm2yDuJ8HrqP1uckhSJCcTOeHMHyh0VqJtnoMhkRAWRPEWcsqIP3sH81riS5ARP1Pv172lVAmfoXnCzwFPNFPnvdSGFk="
+	b, err := base64.StdEncoding.DecodeString(b64)
+	require.NoError(t, err)
+	n, err := p.ReadFrom(bytes.NewReader(b))
+	require.NoError(t, err)
+	require.Equal(t, int64(len(b)), n)*/
+
+	_cs, err := frontend.Compile(ecc.BN254.ScalarField(), r1cs.NewBuilder, &tinyCircuit{})
+	require.NoError(t, err)
+	testRoundtrip(_cs)
+
+	testRoundtrip(getTestCircuit(t))
+}
+
+type tinyCircuit struct {
+	X [4]frontend.Variable `gnark:",public"`
+}
+
+func (c *tinyCircuit) Define(api frontend.API) error {
+	for i := range c.X {
+		api.AssertIsEqual(c.X[i], i)
+	}
+	return nil
+}
+
+func (p *Phase2) Equal(o *Phase2) bool {
+
+	if p.Parameters.G2.Delta != o.Parameters.G2.Delta {
+		print("g2 delta")
+	}
+
+	if p.Delta != o.Delta {
+		print("proof delta")
+	}
+
+	if p.Parameters.G1.Delta != o.Parameters.G1.Delta {
+		print("g1 delta")
+	}
+
+	return p.Parameters.G2.Delta == o.Parameters.G2.Delta &&
+		slices.Equal(p.Sigmas, o.Sigmas) &&
+		// bytes.Equal(p.Challenge, o.Challenge) && This function is used in serialization round-trip testing, and we deliberately don't write the challenges
+		p.Delta == o.Delta &&
+		sliceSliceEqual(p.Parameters.G1.SigmaCKK, o.Parameters.G1.SigmaCKK) &&
+		p.Parameters.G1.Delta == o.Parameters.G1.Delta &&
+		slices.Equal(p.Parameters.G1.Z, o.Parameters.G1.Z) &&
+		slices.Equal(p.Parameters.G1.PKK, o.Parameters.G1.PKK) &&
+		slices.Equal(p.Parameters.G2.Sigma, o.Parameters.G2.Sigma)
+}
+
+func sliceSliceEqual[T comparable](a, b [][]T) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if !slices.Equal(a[i], b[i]) {
+			return false
+		}
+	}
+	return true
+}
diff --git a/go.mod b/go.mod
index fbf26d48f..f5b5106d5 100644
--- a/go.mod
+++ b/go.mod
@@ -19,7 +19,7 @@ require (
 	github.com/ronanh/intcomp v1.1.0
 	github.com/rs/zerolog v1.33.0
 	github.com/stretchr/testify v1.9.0
-	golang.org/x/crypto v0.26.0
+	golang.org/x/crypto v0.31.0
 	golang.org/x/exp v0.0.0-20240823005443-9b4947da3948
 	golang.org/x/sync v0.8.0
 )
@@ -33,7 +33,9 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rogpeppe/go-internal v1.12.0 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
-	golang.org/x/sys v0.24.0 // indirect
+	golang.org/x/sys v0.28.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	rsc.io/tmplfunc v0.0.3 // indirect
 )
+
+replace github.com/consensys/gnark-crypto => /Users/arya/gnark-crypto
diff --git a/go.sum b/go.sum
index e4a044940..51a0a31e8 100644
--- a/go.sum
+++ b/go.sum
@@ -308,6 +308,8 @@ golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97/go.mod h1:GvvjBRRGRdwPK5y
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.26.0 h1:RrRspgV4mU+YwB4FYnuBoKsUapNIL5cohGAmSH3azsw=
 golang.org/x/crypto v0.26.0/go.mod h1:GY7jblb9wI+FOo5y8/S2oY4zWP07AkOJ4+jxCqdqn54=
+golang.org/x/crypto v0.31.0 h1:ihbySMvVjLAeSH1IbfcRTkD/iNscyz8rGzjF/E5hV6U=
+golang.org/x/crypto v0.31.0/go.mod h1:kDsLvtWBEx7MV9tJOj9bnXsPbxwJQ6csT/x4KIN4Ssk=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190306152737-a1d7652674e8/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20190510132918-efd6b22b2522/go.mod h1:ZjyILWgesfNpC6sMxTJOJm9Kp84zZh5NQWvqDGG3Qr8=
@@ -466,6 +468,8 @@ golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.12.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.24.0 h1:Twjiwq9dn6R1fQcyiK+wQyHWfaz/BJB+YIpzU/Cv3Xg=
 golang.org/x/sys v0.24.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.28.0 h1:Fksou7UEQUWlKvIdsqzJmUmCX3cZuD2+P3XyyzwMhlA=
+golang.org/x/sys v0.28.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=
diff --git a/io/roundtrip.go b/io/roundtrip.go
index ecac78afa..66d38aa7c 100644
--- a/io/roundtrip.go
+++ b/io/roundtrip.go
@@ -3,6 +3,7 @@ package io
 import (
 	"bytes"
 	"errors"
+	"fmt"
 	"io"
 	"reflect"
 )
@@ -21,8 +22,8 @@ func RoundTripCheck(from any, to func() any) error {
 			if err != nil {
 				return err
 			}
-			if !reflect.DeepEqual(from, r) {
-				return errors.New("reconstructed object don't match original (ReadFrom)")
+			if err = equal(from, r); err != nil {
+				return fmt.Errorf("ReadFrom: %w", err)
 			}
 			if written != read {
 				return errors.New("bytes written / read don't match")
@@ -35,8 +36,8 @@ func RoundTripCheck(from any, to func() any) error {
 			if err != nil {
 				return err
 			}
-			if !reflect.DeepEqual(from, r) {
-				return errors.New("reconstructed object don't match original (UnsafeReadFrom)")
+			if err = equal(from, r); err != nil {
+				return fmt.Errorf("UnsafeReadFrom: %w", err)
 			}
 			if written != read {
 				return errors.New("bytes written / read don't match")
@@ -52,6 +53,8 @@ func RoundTripCheck(from any, to func() any) error {
 			return err
 		}
 
+		//fmt.Println(base64.StdEncoding.EncodeToString(buf.Bytes()[:written]))
+
 		if err := reconstruct(written); err != nil {
 			return err
 		}
@@ -85,8 +88,28 @@ func DumpRoundTripCheck(from any, to func() any) error {
 	if err := r.ReadDump(bytes.NewReader(buf.Bytes())); err != nil {
 		return err
 	}
-	if !reflect.DeepEqual(from, r) {
-		return errors.New("reconstructed object don't match original (ReadDump)")
+	if err := equal(from, r); err != nil {
+		return fmt.Errorf("ReadDump: %w", err)
 	}
 	return nil
 }
+
+func equal(a, b any) error {
+	// check for a custom Equal method
+	aV := reflect.ValueOf(a)
+	eq := aV.MethodByName("Equal")
+	if eq.IsValid() {
+		res := eq.Call([]reflect.Value{reflect.ValueOf(b)})
+		if len(res) != 1 {
+			return errors.New("`Equal` method must return a single bool")
+		}
+		if res[0].Bool() {
+			return nil
+		}
+		return errors.New("reconstructed object does not match the original (custom Equal)")
+	}
+	if reflect.DeepEqual(a, b) {
+		return nil
+	}
+	return errors.New("reconstructed object does not match the original (reflect.DeepEqual)")
+}