PostgreSQL Anonymizer 0.5: Generalization and k-anonymity - Mailing list pgsql-announce
From | Damien Clochard |
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Subject | PostgreSQL Anonymizer 0.5: Generalization and k-anonymity |
Date | |
Msg-id | 156ba24736cd6c28ff616801129a4de4@dalibo.info Whole thread Raw |
List | pgsql-announce |
_Eymoutiers, France, November 6, 2019_ `Postgresql Anonymizer` is an extension that hides or replaces personally identifiable information (PII) or commercially sensitive data from a PostgreSQL database. The extension supports 3 different anonymization strategies: Dynamic Masking, In-Place Anonymization and Anonymous Dumps. It also offers a large choice of Masking Functions: Substitution, Randomization, Faking, Partial Scrambling, Shuffling, Noise Addition and Generalization. Generalization -------------------------------------------------------------------------------- The idea of generalization is to replace data with a broader, less accurate value. For instance, instead of saying "Bob is 28 years old", you can say "Bob is between 20 and 30 years old". This is interesting for analytics because the data remains true while avoiding the risk of re-identification. PostgreSQL can handle generalization very easily with the RANGE data types, a very powerful way to store and manipulate a set of values contained between a lower and an upper bound. Here's a basic table containing medical data: SELECT * FROM patient; ssn | firstname | zipcode | birth | disease -------------+-----------+---------+------------+--------------- 253-51-6170 | Alice | 47012 | 1989-12-29 | Heart Disease 091-20-0543 | Bob | 42678 | 1979-03-22 | Allergy 565-94-1926 | Caroline | 42678 | 1971-07-22 | Heart Disease 510-56-7882 | Eleanor | 47909 | 1989-12-15 | Acne We want the anonymized data to remain **true** because it will be used for statistics. We can build a view upon this table to remove useless columns and generalize the indirect identifiers (zipcode and birthday): CREATE MATERIALIZED VIEW generalized_patient AS SELECT 'REDACTED'::TEXT AS firstname, anon.generalize_int4range(zipcode,1000) AS zipcode, anon.generalize_daterange(birth,'decade') AS birth, disease FROM patient; This will give us a less accurate view of the data: SELECT * FROM generalized_patient; firstname | zipcode | birth | disease -----------+---------------+-------------------------+--------------- REDACTED | [47000,48000) | [1980-01-01,1990-01-01) | Heart Disease REDACTED | [42000,43000) | [1970-01-01,1980-01-01) | Allergy REDACTED | [42000,43000) | [1970-01-01,1980-01-01) | Heart Disease REDACTED | [47000,48000) | [1980-01-01,1990-01-01) | Acne k-anonymity -------------------------------------------------------------------------------- k-anonymity is an industry-standard term used to describe a property of an anonymized dataset. The k-anonymity principle states that within a given dataset, any anonymized individual cannot be distinguished from at least `k-1` other individuals. In other words, k-anonymity might be described as a "hiding in the crowd" guarantee. A low value of `k` indicates there's a risk of re-identification using linkage with other data sources. You can evaluate the k-anonymity factor of a table in 2 steps : 1/ First defined the columns that are indirect identifiers ( also known as "quasi identifers") like this: SECURITY LABEL FOR anon ON COLUMN generalized_patient.zipcode IS 'INDIRECT IDENTIFIER'; SECURITY LABEL FOR anon ON COLUMN generalized_patient.birth IS 'INDIRECT IDENTIFIER'; 2/ Once the indirect identifiers are declared : SELECT anon.k_anonymity('generalized_patient') In the example above, the k-anonymity factor of the `generalized_patient` materialized view is `2`. Lorem Ipsum -------------------------------------------------------------------------------- For TEXT and VARCHAR columns, you can now use the classic Lorem Ipsum generator: * `anon.lorem_ipsum()` returns 5 paragraphs * `anon.lorem_ipsum(2)` returns 2 paragraphs * `anon.lorem_ipsum( paragraphs := 4 )` returns 4 paragraphs * `anon.lorem_ipsum( words := 20 )` returns 20 words * `anon.lorem_ipsum( characters := 7 )` returns 7 characters How to Install -------------------------------------------------------------------------------- This extension is officially supported on PostgreSQL 9.6 and later. On Red Hat / CentOS systems, you can install it from the official PostgreSQL RPM repository: $ yum install postgresql_anonymizer12 (replace 12 by the major version of your PostgreSQL instance) Then add 'anon' in the `shared_preload_libraries` parameter of your `postgresql.conf` file. And restart your instance. For other system, check out the install documentation : https://postgresql-anonymizer.readthedocs.io/en/latest/INSTALL/ > **WARNING:** The project is at an early stage of development and should > be > used carefully. Thanks -------------------------------------------------------------------------------- This release includes code and ideas from Travis Miller, Jan Birk and Olleg Samoylov. Many thanks to them ! How to contribute -------------------------------------------------------------------------------- PostgreSQL Anonymizer is part of the Dalibo Labs initiative. It is mainly developed by Damien Clochard. This is an open project, contributions are welcome. We need your feedback and ideas ! Let us know what you think of this tool, how it fits your needs and what features are missing. If you want to help, you can find a list of `Junior Jobs` here: https://gitlab.com/dalibo/postgresql_anonymizer/issues?label_name%5B%5D=Junior+Jobs
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