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Decoding Hidden PII in Chinese Identification Numbers

10/19/18 6 minute read

Unique identification numbers are a powerful tool for disambiguating people or companies that may have the same name.

But many analysts don’t realize that the ID numbers themselves often are encoded with additional valuable personally identifiable information (PII). This is even true in jurisdictions like China that are known for protecting the PII of their citizens.

Breaking Down Resident Identity Cards

Chinese Resident Identity Card (居民身份证) numbers, for example, contain date of birth, place of birth, and gender information. Since 1985, all Chinese citizens above 16 years of age have been required to hold a Resident Identity Card issued by the Ministry of Public Security. Each card is printed with basic identifying information, including a unique 16-digit ID number that can be interpreted as follows:



The first six digits of the number are a location code that corresponds to one of China’s 2862 county-level administrative divisions. For individuals born after 1985, this location is their place of birth; for individuals born prior to 1985, this location is their officially-registered residence at the time they first applied for a Resident Identity Card. This number does not change when an individual changes residence.


The next eight digits of the number are the individual’s date of birth, listed in Chinese date order (year, month, date)


The next three digits are a code used to differentiate people born on the same day in the same administrative division. If this code is odd, the individual is male; if it is even, the individual is female.


The final digit or letter is a checksum calculated from the other digits in the ID number.

Understanding Passport Numbers

Similarly, understanding the structure of Chinese passport numbers can help analysts determine whether the passport holder is a government official, diplomat, or member of the public. Chinese passport numbers (护照) are 9 characters long: either a single letter plus eight numerals, or two letters plus seven numerals. Electronic passports include in E in the first two characters.

Diplomatic (D/DE)

Used by diplomats. Only good for five years.

Service (S/SE)

Used by government officials who are abroad on official business; this includes families of diplomats and senior government officials. Only good for five years.

Service General (S/SE)

Used by lower-ranking government officials (副处级 and below) who are abroad on official business; also available for anyone else abroad on official business, such as laborers or journalists. Only good for five years.

General (G/E)

Used by the general population for personal travel; the most common form of passport. Good for ten years if issued to a person age sixteen or above.

The public records data that powered this research is available through Sayari Search. If you’re curious how this data could drive insights for your team, or for details on the specific individuals and companies discussed above, please reach out here.

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