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Personally identifiable information (PII) model

We recognize a number of data types that can potentially identify a person, like name or email. We also take into account the context within which this particular data was used, like a combination of the first and last names with the street address, or whether the name was actually a company name and not person's name. Based on that, we reason whether that usage posed a risk of actually identifying a person, and how high was that risk.

You can think of the Soveren PII model as a two-stage classifier. First, for each observed value the classifier determines a data type, for example email. Then, depending on the context, the classifier decides if this was actually PII or not, that is if the person's identity could actually be revealed if the observed value was disclosed.

On top of that, the model assigns different weights or sensitivities to different PII data types and their combinations. Those sensitivities define how likely it is to get the actual person's identity when this data is disclosed.

Recognised PII data types

Soveren works with the following types of potential PII data:

  • Person. This is a person's name which can be any combination of the first and last names.
  • Birth date: date of birth of a person. This can be any conceivable representation of a date, in the form of any combination of day / month / year, or even a Unix timestamp.
  • Gender, or more precisely sex of a person (male or female).
  • US Driver license number (or code).
  • Passport data, including the number.
  • Tax number, or Taxpayer Identification Number. Depends on the country. Special case is the US Social Security Number (SSN)
  • Pension number, depends on the country.
  • Credit or debit Card, including the number (checked for validity according to standards) and expiration date.
  • Phone number.
  • Email address.
  • Location where the person may reside, i.e. to be present physically, or live or receive a postage. This includes coordinates like latitude / longitude and all details of physical address (country code / city / street / building etc).
  • IBAN: international bank account number.
  • IP address.

The list of supported data types is ever-growing. Drop us a line if you think that we should support some particular data type which you'd use as PII.

PII sensitivity model

We consider both individual PII data types and their combinations, because sensitivity of the combined data set can be significantly higher than that of any individual value. For example, the name itself does not reveal much in terms of identification when used alone. But the name combined with the postal address can reveal the identity with much higher certainty.

There are three levels of sensitivity: Low, Medium and High.

The PII data types are individually assigned the following levels:

  • Low: Birth date, Gender
  • Medium: Person, Phone, Email, IP address
  • High: Location, Card, Driver license, Passport, Tax number, SSN, Pension number, IBAN

The sensitivity levels are assigned different numerical weights, so that PII data type combinations result in different combined sensitivities. For example, Birth date combined with Gender still result in Low sensitivity. Similarly, Person + Phone + Email are of Medium sensitivity, whereas Person + Phone + Email + Gender is of High sensitivity from the potential person's identification point of view.