From 8d51fa233e594b84b5b6e311a872978d60768076 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lucas=20Men=C3=A9ndez?= <hi@lucasmenendez.me>
Date: Wed, 15 Jan 2025 09:11:01 +0100
Subject: [PATCH] remove the LE address return from address derivation
 primitive and fix test struct typo

---
 emulated/ecdsa/address.go      | 19 +++++++------------
 emulated/ecdsa/address_test.go | 13 ++++---------
 testutil/utils.go              |  6 +++---
 3 files changed, 14 insertions(+), 24 deletions(-)

diff --git a/emulated/ecdsa/address.go b/emulated/ecdsa/address.go
index 3120a11..a179114 100644
--- a/emulated/ecdsa/address.go
+++ b/emulated/ecdsa/address.go
@@ -10,24 +10,23 @@ import (
 
 // DeriveAddress derives an Ethereum address from a public key over Secp256k1
 // by hashing the public key with Keccak256 and returning the last 20 bytes of
-// the hash as an address into a variable. It also returns the address with the
-// bytes in little-endian order.
-func DeriveAddress(api frontend.API, pubKey ecdsa.PublicKey[emulated.Secp256k1Fp, emulated.Secp256k1Fr]) (frontend.Variable, frontend.Variable, error) {
+// the hash as an address into a variable.
+func DeriveAddress(api frontend.API, pubKey ecdsa.PublicKey[emulated.Secp256k1Fp, emulated.Secp256k1Fr]) (frontend.Variable, error) {
 	// convert public key coords to uint8 and concatenate them
 	xBytes, err := utils.ElemToU8(api, pubKey.X)
 	if err != nil {
-		return 0, 0, err
+		return 0, err
 	}
 	yBytes, err := utils.ElemToU8(api, pubKey.Y)
 	if err != nil {
-		return 0, 0, err
+		return 0, err
 	}
 	// swap endianness of the bytes and concatenate them
 	pubBytes := append(utils.SwapEndianness(xBytes), utils.SwapEndianness(yBytes)...)
 	// hash the public key
 	keccak, err := sha3.NewLegacyKeccak256(api)
 	if err != nil {
-		return 0, 0, err
+		return 0, err
 	}
 	keccak.Write(pubBytes)
 	hash := keccak.Sum()
@@ -35,11 +34,7 @@ func DeriveAddress(api frontend.API, pubKey ecdsa.PublicKey[emulated.Secp256k1Fp
 	addrBytes := hash[12:]
 	addr, err := utils.U8ToVar(api, addrBytes)
 	if err != nil {
-		return 0, 0, err
+		return 0, err
 	}
-	addrLE, err := utils.U8ToVar(api, utils.SwapEndianness(addrBytes))
-	if err != nil {
-		return 0, 0, err
-	}
-	return addr, addrLE, nil
+	return addr, nil
 }
diff --git a/emulated/ecdsa/address_test.go b/emulated/ecdsa/address_test.go
index 7de4de4..e7d19c8 100644
--- a/emulated/ecdsa/address_test.go
+++ b/emulated/ecdsa/address_test.go
@@ -2,7 +2,6 @@ package ecdsa
 
 import (
 	"fmt"
-	"math/big"
 	"testing"
 	"time"
 
@@ -20,18 +19,16 @@ import (
 )
 
 type testAddressCircuit struct {
-	Address             frontend.Variable `gnark:",public"`
-	AddressLittleEndian frontend.Variable `gnark:",public"`
-	PublicKey           gecdsa.PublicKey[emulated.Secp256k1Fp, emulated.Secp256k1Fr]
+	Address   frontend.Variable `gnark:",public"`
+	PublicKey gecdsa.PublicKey[emulated.Secp256k1Fp, emulated.Secp256k1Fr]
 }
 
 func (c *testAddressCircuit) Define(api frontend.API) error {
-	addr, addrLE, err := DeriveAddress(api, c.PublicKey)
+	addr, err := DeriveAddress(api, c.PublicKey)
 	if err != nil {
 		return err
 	}
 	api.AssertIsEqual(c.Address, addr)
-	api.AssertIsEqual(c.AddressLittleEndian, addrLE)
 	return nil
 }
 
@@ -56,11 +53,9 @@ func TestAddressDerivation(t *testing.T) {
 	input := crypto.Keccak256Hash([]byte("hello")).Bytes()
 	testSig, err := testutil.GenerateAccountAndSign(input)
 	c.Assert(err, qt.IsNil)
-	addrLE := new(big.Int).SetBytes(goSwapEndianness(testSig.Address.Bytes()))
 	// init inputs
 	witness := testAddressCircuit{
-		Address:             testSig.Address,
-		AddressLittleEndian: addrLE,
+		Address: testSig.Address,
 		PublicKey: gecdsa.PublicKey[emulated.Secp256k1Fp, emulated.Secp256k1Fr]{
 			X: emulated.ValueOf[emulated.Secp256k1Fp](testSig.PublicKey.X),
 			Y: emulated.ValueOf[emulated.Secp256k1Fp](testSig.PublicKey.Y),
diff --git a/testutil/utils.go b/testutil/utils.go
index 9387ea6..a533f1c 100644
--- a/testutil/utils.go
+++ b/testutil/utils.go
@@ -25,7 +25,7 @@ type CensusTestConfig struct {
 	TotalSiblings int
 	KeyLen        int
 	Hash          arbotree.HashFunction
-	BaseFiled     *big.Int
+	BaseField     *big.Int
 }
 
 // TestCensusProofs is a structure to store the key, value, and siblings of a
@@ -77,14 +77,14 @@ func GenerateCensusProofForTest(conf CensusTestConfig, ks, vs [][]byte) (*TestCe
 	}
 	// add the key-value pairs
 	for i, k := range ks {
-		k = arbotree.BigToFF(conf.BaseFiled, new(big.Int).SetBytes(k)).Bytes()
+		k = arbotree.BigToFF(conf.BaseField, new(big.Int).SetBytes(k)).Bytes()
 		if err = tree.Add(k, vs[i]); err != nil {
 			return nil, err
 		}
 	}
 	// add random addresses
 	for i := 1; i < conf.ValidSiblings; i++ {
-		rk := arbotree.BigToFF(conf.BaseFiled, new(big.Int).SetBytes(util.RandomBytes(conf.KeyLen))).Bytes()
+		rk := arbotree.BigToFF(conf.BaseField, new(big.Int).SetBytes(util.RandomBytes(conf.KeyLen))).Bytes()
 		rv := new(big.Int).SetBytes(util.RandomBytes(8)).Bytes()
 		if err = tree.Add(rk, rv); err != nil {
 			return nil, err