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FIDIS 

Future of Identity in the Information Society (No. 507512)

 

D2.3 

  

[Final], Version: 2.0 

File: fidis-wp2-del2.3.models.doc 

Page 22 

 

3.2.4 An example of the use of an attribute: the ssn (social security 

number)  

Governments in general tend to make their habitants identifiable for different reasons. Several 

techniques for this purpose exist, as well as different legislations in various countries which 

imply different types. For the purpose of giving concrete examples, we will focus here on ssn 

implementation in three different countries, namely Switzerland, the US and France, and 

specifically what information is coded in the ssn. 

 

The ssn in Switzerland 

In Switzerland there is in fact no nationwide identification number available at the moment. 

This is the case for several reasons: first the federal structure of the country, second no one is 

obliged to possess either a passport or identity card, but also because many citizens are 

opposed to such a unique number in general. Notably however, there are plans for a unique 

number to be used for health care. At the moment, the only thing close to a unique identifier 

for people is the social security number (called AHV). This is a unique number attached only 

to persons who receive income and is delivered to the person usually when he/she starts 

employment. Hence only part of the population has and is therefore identifiable by such a 

number. Further, depending on different reasons, this number changes with time (marriage, 

change of name, sex, nationality, etc.). The number is used for different purposes, mainly for 

contacts between people and governmental agencies, and not only social security. Rarely is it 

used in the private sector. 

Technically, the number consists of 11 digits, from which information about the holder can be 

deduced

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: Consider for example the number 123'45'678'113. The first three digits (123 in the 

example) depend on the name of the holder, beginning with 100 for names between “A” and 

“Abi”, with 101 for names between “Abi” and “Abl”, and so on. The next two digits (45 in 

the example) denote the year of birth, the following three (678 in the example) the day and 

month of birth as well as the sex of the person, where roughly the first one denotes the quarter 

of the birth (1-4 for male, 5-8 for females) and the other two the day in the respective quarter. 

For example 678 means that the holder of the number is female and born June 16th (i.e. the 

78th day of the 2nd quarter). The next two digits (11 in the example) are a running number 

delivered by a central office in Switzerland in order to differentiate between persons having 

identical first 8 digits. The second of these numbers tells if the holder is a Swiss citizen 

(numbers between 1 and 4) or foreign citizen (numbers from 5 to 8). The last digit is a 

weighted check sum used to ensure the integrity of the number when used and depends on the 

other 10 digits.  

 

The SSN in the US 

A concept very close to the Swiss one exists in the US, the SSN (Social Security Number

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). 

Each person over 18 who receives income must have an SSN, although it is possible for 

anyone, including children to have one. In the US, the SSN is used in a variety of sectors 

besides social security, for example for opening a saving account; hence a large part of the 

                                                 

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http://www.ahv.ch/Home-D/allgemeines/31810612d.pdf

 

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http://www.ssa.gov/

 

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FIDIS 

Future of Identity in the Information Society (No. 507512)

 

D2.3 

  

[Final], Version: 2.0 

File: fidis-wp2-del2.3.models.doc 

Page 23 

 

population has a SSN. The SSN does not change in the person’s lifetime (besides some very 

rare cases), only the physical card carrying the number is replaced, e.g. when changing name 

because of marriage.  

Technically, the SSN consists of nine digits which decompose into area numbers (3 digits), 

group numbers (2 digits) and serial numbers (4 digits). The area number relates to the state 

the application for the number comes from. The group numbers are used to “break” the area 

numbers into different pieces following a specific scheme. The serial numbers run through 

0001 to 9999 without further information contained therein. Hence there is almost no 

information about the holder contained in this number. Some ideas about the age might be 

gathered from the group number. 

 

The SSN in France 

The French Social Security Number

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 contains information, that is clearly readable, about the 

user. The first digit stands for the gender (1 for male and 2 for female), then comes two digits 

for the year of the birth and two other digits for its month. The next two digits represent the 

department of birth (one of the 95 administrative subdivisions of the country). The three next 

digits represent the city of birth and the last three digits are for the rank within the register of 

births in this city. It is therefore possible to know precisely the sex and age of the SSN holder, 

and from which region he or she comes from. 

 

The differences 

What is the difference between coding lots of information in the AHV-number (like in 

Switzerland) opposed to coding almost no information in the SSN (like in the US)? There is 

on one hand the problem of data protection: everyone in possession of the AHV number can 

deduce all things described above, e.g. age, sex of the holder. This information is not 

protected. On the other hand, everyone can – at least to some degree – check if some number 

really belongs to a person claiming to be its owner. Typically this is done by cross referencing 

data contained in some other credential like a passport (containing name and date of birth) 

with the info contained in the AHV number. On the other hand, the SSN allows the holder to 

not disclose any information about himself. Clearly this raises the problem of SSN 

falsification, fraud detection, etc.  

 

3.2.5  Relevant standards and specifications 

Most standards specify some attributes which have identification as a principal role. For 

instance the name of a person, if present, is the major representation specification in LDAP, 

vCard, HR-XML, IMS-LIP, JXDM, etc.

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Some specifications are however addressing more specifically the identification dimension, 

and in particular provide more sophisticated “identification attributes”. 

                                                 

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http://www.dads.cnav.fr/TDS/stru0103.htm

 

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 See the Annex for more detailed information about these specifications. 

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