I assume that you don't want "normal" Limesurvey users to have access to the personal data of the respondents. As Jelo says, there is no such thing of encrypting some answers.
What you could do is to create two surveys, one for the survey data and then, if respondents agree, they are forwarded (see end url feature) to the next survey where they can leave their personal data. You then restrict the access to the content of this second survey.
What you could do is to create two surveys, one for the survey data and then, if respondents agree, they are forwarded (see end url feature) to the next survey where they can leave their personal data. You then restrict the access to the content of this second survey.
