// Assert
        verify(signingDigest, times(1)).sign(testData, offset, length, null, null);
    }

    @Test
    @DisplayName("Test verify method with null message")
    void testVerifyWithNullMessage() {
        // Arrange
        int offset = 0;
        int length = testData.length;
        int extraPad = 0;
        when(signingDigest.verify(testData, offset, length, extraPad, null)).thenReturn(false);