Methods, systems, and apparatus, including computer programs encoded on computer storage media, for receiving, from a user device, a request to include financial data describing a financial account in an interface, the financial account being associated with a particular financial institution; identifying one or more metadata attributes for accessing the financial account associated with the particular financial institution; obtaining a public digital key associated with the financial institution; providing, to the user device, data describing the one or more metadata attributes and the public digital key associated with the financial institution; receiving, from the user device, respective values for the one or more metadata attributes, the corresponding values having been encrypted by the user device using the public digital key; and storing the encrypted values for the one or more metadata attributes for use in accessing and aggregating financial data describing the financial account.