Pseudonymization Keys enable researchers to connect personal data to anonymized research data. When stored using BIDS format, research data will be organized at the subject level - though these subject identifiers should not be sufficient to determine the subject’s identity. The pseudonymization key is what allows a research to connect the subject’s personal (i.e. potentially identifying) information to their research data.
We recommend that you store pseudonymization keys in either your home or groupshare drive: it must NEVER be stored in the project folder. The pseudonymization key should be password protected. Access to the pseudonymization key (i.e. sharing of the password) should be given on a strictly need-to-know basis.