A facility stores a person's personal information (“PI”) on a portable storage device (“PSD”) of the person. In some cases, the PSD bears a fax number mapping uniquely to the person; when a fax containing the person's PI is sent to this fax number, the facility stores an encrypted version of the PI on a relay server (“RS”). When the PSD connects with an access device, the encrypted version of the PI is retrieved from the RS and stored on the PSD. In some cases, the PSD bears a non-textual visual symbol; when its images is captured by a device such as a smartphone, an identifier encoded in the symbol is used to transmit encrypted PI to the RS. In some cases, each access device reports aggregates of personal data to an analysis server. In some cases, the facility statistically obfuscates these aggregates for transmission to/storage on the analysis server.