*: replace slice.Clean() with clear()

Signed-off-by: Roman Khimov <roman@nspcc.ru>

pkg/crypto/keys/nep2.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/encoding/base58"
-	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 	"golang.org/x/crypto/scrypt"
 	"golang.org/x/text/unicode/norm"
 )
@@ -53,15 +52,15 @@ func NEP2Encrypt(priv *PrivateKey, passphrase string, params ScryptParams) (s st
 	if err != nil {
 		return s, err
 	}
-	defer slice.Clean(derivedKey)
+	defer clear(derivedKey)
 
 	derivedKey1 := derivedKey[:32]
 	derivedKey2 := derivedKey[32:]
 
 	privBytes := priv.Bytes()
-	defer slice.Clean(privBytes)
+	defer clear(privBytes)
 	xr := xor(privBytes, derivedKey1)
-	defer slice.Clean(xr)
+	defer clear(xr)
 
 	encrypted, err := aesEncrypt(xr, derivedKey2)
 	if err != nil {
@@ -99,7 +98,7 @@ func NEP2Decrypt(key, passphrase string, params ScryptParams) (*PrivateKey, erro
 	if err != nil {
 		return nil, err
 	}
-	defer slice.Clean(derivedKey)
+	defer clear(derivedKey)
 
 	derivedKey1 := derivedKey[:32]
 	derivedKey2 := derivedKey[32:]
@@ -109,10 +108,10 @@ func NEP2Decrypt(key, passphrase string, params ScryptParams) (*PrivateKey, erro
 	if err != nil {
 		return nil, err
 	}
-	defer slice.Clean(decrypted)
+	defer clear(decrypted)
 
 	privBytes := xor(decrypted, derivedKey1)
-	defer slice.Clean(privBytes)
+	defer clear(privBytes)
 
 	// Rebuild the private key.
 	privKey, err := NewPrivateKeyFromBytes(privBytes)

pkg/crypto/keys/private_key.go

@@ -13,7 +13,6 @@ import (
 	"github.com/decred/dcrd/dcrec/secp256k1/v4"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
 	"github.com/nspcc-dev/neo-go/pkg/util"
-	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 	"github.com/nspcc-dev/rfc6979"
 )
 
@@ -49,7 +48,7 @@ func NewPrivateKeyFromHex(str string) (*PrivateKey, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer slice.Clean(b)
+	defer clear(b)
 	return NewPrivateKeyFromBytes(b)
 }
 
@@ -111,7 +110,7 @@ func NewPrivateKeyFromWIF(wif string) (*PrivateKey, error) {
 // https://en.bitcoin.it/wiki/Wallet_import_format
 func (p *PrivateKey) WIF() string {
 	pb := p.Bytes()
-	defer slice.Clean(pb)
+	defer clear(pb)
 	w, err := WIFEncode(pb, WIFVersion, true)
 	// The only way WIFEncode() can fail is if we're to give it a key of
 	// wrong size, but we have a proper key here, aren't we?
@@ -124,10 +123,7 @@ func (p *PrivateKey) WIF() string {
 // Destroy wipes the contents of the private key from memory. Any operations
 // with the key after call to Destroy have undefined behavior.
 func (p *PrivateKey) Destroy() {
-	bits := p.D.Bits()
-	for i := range bits {
-		bits[i] = 0
-	}
+	clear(p.D.Bits())
 }
 
 // Address derives the public NEO address that is coupled with the private key, and

pkg/crypto/keys/wif.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 
 	"github.com/nspcc-dev/neo-go/pkg/encoding/base58"
-	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 )
 
 const (
@@ -54,7 +53,7 @@ func WIFDecode(wif string, version byte) (*WIF, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer slice.Clean(b)
+	defer clear(b)
 
 	if version == 0x00 {
 		version = WIFVersion

pkg/util/slice/array.go

@@ -21,10 +21,3 @@ func reverse(dst []byte, src []byte) {
 		dst[i], dst[j] = src[j], src[i]
 	}
 }
-
-// Clean wipes the data in b by filling it with zeros.
-func Clean(b []byte) {
-	for i := range b {
-		b[i] = 0
-	}
-}

pkg/util/slice/array_test.go

@@ -50,11 +50,3 @@ func TestCopyReverse(t *testing.T) {
 		}
 	}
 }
-
-func TestClean(t *testing.T) {
-	for _, tc := range testCases[1:] { // Empty one will be equal.
-		cp := bytes.Clone(tc.arr)
-		Clean(cp)
-		require.NotEqual(t, tc.arr, cp)
-	}
-}