Philter User's Guide Help

De-identification Methods

There are several ways data can be de-identified, and which you use depends on the types of data you want to de-identify and your use-case for de-identifying the data. The terminology around the different methods is often used interchangeably, but there are differences between each method.

In Philter, de-identification methods vary for each type of sensitive information. For example, all types can be replaced or redacted, but only dates can be shifted and only zip codes can be truncated. How a de-identification method is applied by Philter is called a filter strategy. Each type of sensitive information can have one or more filter strategies, and the combination of the filter strategies you select is called a policy. A policy determines how a document will be de-identified.

The following is a list of de-identification methods that describes how each method works and its applicability to our Philter software. De-identifying a document is likely to require a combination of the following methods. For instance, you may want to redact names, encrypt credit card numbers, and shift appointment dates.

De-identification Method



Replaces sensitive information with a defined value. For example, you might want to replace a credit card number with the literal value "CREDIT_CARD_NUMBER".

Redaction and Masking

Removes sensitive information. Our Philter software gives you a choice of how to remove the sensitive information, whether it is by replacing it with ***** (masking) or by some other set of characters.


Encrypts sensitive information.

Date Shifting

Shifts dates either forward or backward by some interval.


Categorizes data into buckets based on the data. Examples of bucketing is Philter can bucket dates into years, and zip codes by population.

Last modified: 08 November 2023