verify(signingDigest, times(1)).verify(testData, offset, length, extraPad, message);
    }

    @Test
    @DisplayName("Test verify method returns false for invalid signature")
    void testVerifyReturnsFalse() {
        // Arrange
        int offset = 0;
        int length = testData.length;
        int extraPad = 0;
        when(signingDigest.verify(testData, offset, length, extraPad, message)).thenReturn(false);