When debugging in Eclipse, I step into (F5) a statement such as the following,
encryptedBytes = LightWeightEncryptor.encrypt(messageBytes, password.toCharArray()
Try Eclipse menu : Window -> Preferences -> Java|Debug|Step Filtering.
Toggle "Use Step Filters", you may choose the step filters from the checkbox list.
E.g. check "java.*", then the JRE method String.xxx() will be skipped.