[FAB-3176] Fixing staticcheck errors

This change-set fixes staticcheck errors in bccsp/sw
package.

Change-Id: I48179b848f40a095fea8f545407a8146651e489f
Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

bccsp/sw/aes_test.go

@@ -23,6 +23,7 @@ import (
 	"testing"
 
 	"github.com/hyperledger/fabric/bccsp/utils"
+	"github.com/stretchr/testify/assert"
 )
 
 // TestCBCPKCS7EncryptCBCPKCS7Decrypt encrypts using CBCPKCS7Encrypt and decrypts using CBCPKCS7Decrypt.
@@ -288,8 +289,7 @@ func TestCBCEncrypt_EmptyPlaintext(t *testing.T) {
 	t.Log("Message length: ", len(emptyPlaintext))
 
 	ciphertext, encErr := aesCBCEncrypt(key, emptyPlaintext)
-	if encErr != nil {
-	}
+	assert.NoError(t, encErr)
 
 	t.Log("Ciphertext length: ", len(ciphertext))
 

bccsp/sw/fileks.go

@@ -230,6 +230,9 @@ func (ks *fileBasedKeyStore) searchKeystoreForSKI(ski []byte) (k bccsp.Key, err
 			continue
 		}
 		raw, err := ioutil.ReadFile(filepath.Join(ks.path, f.Name()))
+		if err != nil {
+			continue
+		}
 
 		key, err := utils.PEMtoPrivateKey(raw, ks.pwd)
 		if err != nil {

bccsp/sw/impl_test.go

@@ -1095,7 +1095,7 @@ func TestECDSALowS(t *testing.T) {
 		t.Fatalf("Failed generating ECDSA signature [%s]", err)
 	}
 
-	R, S, err := unmarshalECDSASignature(signature)
+	_, S, err := unmarshalECDSASignature(signature)
 	if err != nil {
 		t.Fatalf("Failed unmarshalling signature [%s]", err)
 	}
@@ -1113,6 +1113,7 @@ func TestECDSALowS(t *testing.T) {
 	}
 
 	// Ensure that signature with high-S are rejected.
+	var R *big.Int
 	for {
 		R, S, err = ecdsa.Sign(rand.Reader, k.(*ecdsaPrivateKey).privKey, digest)
 		if err != nil {