fix logon problem with oracle 12.1.0.2 and high

with sec_case_sensitive_logon=false and
SQLNET.ALLOWED_LOGON_VERSION_SERVER=11

auth_object.go

@@ -492,27 +492,31 @@ func (obj *AuthObject) generatePasswordEncKey() ([]byte, error) {
 	key1 := obj.ServerSessKey
 	key2 := obj.ClientSessKey
 	start := 16
+	var retKeyLen int
 	logonCompatibility := obj.tcpNego.ServerCompileTimeCaps[4]
 	if logonCompatibility&32 != 0 {
 		var keyBuffer string
 		switch obj.VerifierType {
 		case 2361:
 			buffer := append(key2[:len(key2)/2], key1[:len(key1)/2]...)
 			keyBuffer = fmt.Sprintf("%X", buffer)
+			retKeyLen = 16
 		case 6949:
 			buffer := append(key2[:24], key1[:24]...)
 			keyBuffer = fmt.Sprintf("%X", buffer)
+			retKeyLen = 24
 		case 18453:
 			buffer := append(key2, key1...)
 			keyBuffer = fmt.Sprintf("%X", buffer)
+			retKeyLen = 32
 		default:
 			return nil, errors.New("unsupported verifier type")
 		}
 		df2key, err := HexStringToBytes(obj.pbkdf2ChkSalt)
 		if err != nil {
 			return nil, err
 		}
-		return generateSpeedyKey(df2key, []byte(keyBuffer), obj.pbkdf2SderCount)[:32], nil
+		return generateSpeedyKey(df2key, []byte(keyBuffer), obj.pbkdf2SderCount)[:retKeyLen], nil
 	} else {
 		switch obj.VerifierType {
 		case 2361: