Is it considered a lie to feign ignorance about a subject in order to keep a promise not to reveal it?

If feigning ignorance does not involve informing against reality, such as ignoring the subject or shifting it to another, then there is no blame in it, and it is not a lie. However, if there is an utterance by the tongue claiming ignorance about the subject, it is considered a lie. Yet, it is not forbidden due to the overriding benefit it contains, such as preserving people's secrets. Using evasive language (ma'areedh) is preferable to outright lying.