crypto: add SignatureLength constant and use it everywhere (#19996)

Original change by @jpeletier 

2 files changed, 5 insertions, 4 deletions

diff --git a/core/genesis.go b/core/genesis.go
index 87bab2520..5d6311b32 100644
--- a/core/genesis.go
+++ b/core/genesis.go
@@ -31,6 +31,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/rawdb"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
@@ -377,7 +378,7 @@ func DeveloperGenesisBlock(period uint64, faucet common.Address) *Genesis {
 	// Assemble and return the genesis with the precompiles and faucet pre-funded
 	return &Genesis{
 		Config:     &config,
-		ExtraData:  append(append(make([]byte, 32), faucet[:]...), make([]byte, 65)...),
+		ExtraData:  append(append(make([]byte, 32), faucet[:]...), make([]byte, crypto.SignatureLength)...),
 		GasLimit:   6283185,
 		Difficulty: big.NewInt(1),
 		Alloc: map[common.Address]GenesisAccount{
diff --git a/core/types/transaction_signing.go b/core/types/transaction_signing.go
index 63132048e..842fedbd0 100644
--- a/core/types/transaction_signing.go
+++ b/core/types/transaction_signing.go
@@ -193,8 +193,8 @@ func (s FrontierSigner) Equal(s2 Signer) bool {
 // SignatureValues returns signature values. This signature
 // needs to be in the [R || S || V] format where V is 0 or 1.
 func (fs FrontierSigner) SignatureValues(tx *Transaction, sig []byte) (r, s, v *big.Int, err error) {
-	if len(sig) != 65 {
-		panic(fmt.Sprintf("wrong size for signature: got %d, want 65", len(sig)))
+	if len(sig) != crypto.SignatureLength {
+		panic(fmt.Sprintf("wrong size for signature: got %d, want %d", len(sig), crypto.SignatureLength))
 	}
 	r = new(big.Int).SetBytes(sig[:32])
 	s = new(big.Int).SetBytes(sig[32:64])
@@ -229,7 +229,7 @@ func recoverPlain(sighash common.Hash, R, S, Vb *big.Int, homestead bool) (commo
 	}
 	// encode the signature in uncompressed format
 	r, s := R.Bytes(), S.Bytes()
-	sig := make([]byte, 65)
+	sig := make([]byte, crypto.SignatureLength)
 	copy(sig[32-len(r):32], r)
 	copy(sig[64-len(s):64], s)
 	sig[64] = V