From f48be088146911fd52997933f19112db695d28d9 Mon Sep 17 00:00:00 2001
From: Kirill <paltsev.kir@gmail.com>
Date: Tue, 23 Jul 2024 21:24:16 +0300
Subject: [PATCH] Remove returned error from crypto.StarknetKeccak function
 (#1963)

---
 adapters/p2p2core/class.go  |  5 +----
 adapters/sn2core/sn2core.go |  6 +-----
 core/crypto/keccak.go       | 10 +++++++---
 core/crypto/keccak_test.go  |  5 +----
 4 files changed, 10 insertions(+), 16 deletions(-)

diff --git a/adapters/p2p2core/class.go b/adapters/p2p2core/class.go
index 8094a03006..40c5a7bc51 100644
--- a/adapters/p2p2core/class.go
+++ b/adapters/p2p2core/class.go
@@ -35,10 +35,7 @@ func AdaptClass(class *spec.Class) core.Class {
 		}
 	case *spec.Class_Cairo1:
 		cairo1 := cls.Cairo1
-		abiHash, err := crypto.StarknetKeccak([]byte(cairo1.Abi))
-		if err != nil {
-			panic(err)
-		}
+		abiHash := crypto.StarknetKeccak([]byte(cairo1.Abi))
 
 		program := utils.Map(cairo1.Program, AdaptFelt)
 		compiled, err := createCompiledClass(cairo1)
diff --git a/adapters/sn2core/sn2core.go b/adapters/sn2core/sn2core.go
index 326a643a3b..27b774cf6a 100644
--- a/adapters/sn2core/sn2core.go
+++ b/adapters/sn2core/sn2core.go
@@ -256,15 +256,11 @@ func AdaptCairo1Class(response *starknet.SierraDefinition, compiledClass *starkn
 	class.ProgramHash = crypto.PoseidonArray(class.Program...)
 
 	class.Abi = response.Abi
-	class.AbiHash, err = crypto.StarknetKeccak([]byte(class.Abi))
-	if err != nil {
-		return nil, err
-	}
+	class.AbiHash = crypto.StarknetKeccak([]byte(class.Abi))
 
 	adapt := func(ep starknet.SierraEntryPoint) core.SierraEntryPoint {
 		return core.SierraEntryPoint{Index: ep.Index, Selector: ep.Selector}
 	}
-
 	class.EntryPoints.External = utils.Map(utils.NonNilSlice(response.EntryPoints.External), adapt)
 	class.EntryPoints.L1Handler = utils.Map(utils.NonNilSlice(response.EntryPoints.L1Handler), adapt)
 	class.EntryPoints.Constructor = utils.Map(utils.NonNilSlice(response.EntryPoints.Constructor), adapt)
diff --git a/core/crypto/keccak.go b/core/crypto/keccak.go
index 8bded1232b..5e2554d91a 100644
--- a/core/crypto/keccak.go
+++ b/core/crypto/keccak.go
@@ -1,6 +1,8 @@
 package crypto
 
 import (
+	"fmt"
+
 	"github.com/NethermindEth/juno/core/felt"
 	"golang.org/x/crypto/sha3"
 )
@@ -8,14 +10,16 @@ import (
 // StarknetKeccak implements [Starknet keccak]
 //
 // [Starknet keccak]: https://docs.starknet.io/architecture-and-concepts/cryptography/hash-functions/#starknet_keccak
-func StarknetKeccak(b []byte) (*felt.Felt, error) {
+func StarknetKeccak(b []byte) *felt.Felt {
 	h := sha3.NewLegacyKeccak256()
 	_, err := h.Write(b)
 	if err != nil {
-		return nil, err
+		// actual implementation (sha3.state{} type) doesn't return error in Write method
+		// we keep this panic as an assertion in case they will modify the implementation
+		panic(fmt.Errorf("failed to write to LegacyKeccak256 hash: %w", err))
 	}
 	d := h.Sum(nil)
 	// Remove the first 6 bits from the first byte
 	d[0] &= 3
-	return new(felt.Felt).SetBytes(d), nil
+	return new(felt.Felt).SetBytes(d)
 }
diff --git a/core/crypto/keccak_test.go b/core/crypto/keccak_test.go
index 39dc24a0e7..5b5d7cbccc 100644
--- a/core/crypto/keccak_test.go
+++ b/core/crypto/keccak_test.go
@@ -6,7 +6,6 @@ import (
 
 	"github.com/NethermindEth/juno/core/crypto"
 	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 )
 
 func TestStarknetKeccak(t *testing.T) {
@@ -22,11 +21,9 @@ func TestStarknetKeccak(t *testing.T) {
 	t.Parallel()
 
 	for _, test := range tests {
-		test := test
 		t.Run(test.input, func(t *testing.T) {
 			t.Parallel()
-			d, err := crypto.StarknetKeccak([]byte(test.input))
-			require.NoError(t, err)
+			d := crypto.StarknetKeccak([]byte(test.input))
 
 			got := fmt.Sprintf("%x", d.Bytes())
 			assert.Equal(t, test.want, got)