# [IAEP] Cédula de Identidad Uruguaya - Dígito de Control / Uruguayan ID Card - Control Digit

Chris Leonard cjlhomeaddress at gmail.com
Tue Nov 8 09:53:16 EST 2011

```2011/11/8 Carlos Rabassa <carnen at mac.com>

>
> *English Text:*
> *
> *
> We believe this could be an interesting subject for a project using some
> of the applications in the Plan Ceibal computers.
>
>

> The first project we would like to suggest is to just repeat the
> calculation we show,  using one or more of the applications in Plan Ceibal´
> computers.
>
> Then,  it could be resolving other problems:
>
> - Given seven of the eight digits in an ID card,  calculate the missing
> digit.
>
> -  Whenever there is an error,  is the calculation going to return the
> wrong control digit?  Justify the answer.
>
> - If we transpose two consecutive digits,  a very frequent error, will the
> calculation result change? Are we going to be able,  in such case,  to find
> out what the error was and correct it?
>
> - Are there other applications in the real world for control digits,
>  besides the ID card?
>
> We will be glad to send the paper by Omar Gil and Ricardo Vilaró,
>  mentioned in the attached spreadsheet, to anyone who might wish to further
> study the subject and do other exercises.
>
>

[Español abajo]

Carlos,

The system you describe is generally referred to as a "checksum".

http://en.wikipedia.org/wiki/Checksum

http://es.wikipedia.org/wiki/Suma_de_verificaci%C3%B3n

There are multiple algorithms for calculating check sums and each has
fdifferent features.

Checksum methods typically employ some form of hashing (from the simple to
the complex) and depending on the hashing algorithm used and the
construction of the identifier they are used on (e.g. all digits, digits
and letters) , checksums are capable of detecting transposition errors,
simple single substitutions and / or double substitutions.

http://en.wikipedia.org/wiki/List_of_hash_functions

Checksums are widely used in barcoding applications and data transmission
to look for data corruption. They are used in all banking transactions and
are probably printed on your checkbook.

The International Standards Organization publishes:
ISO/IEC 7064:2003 "Information technology -- Security techniques -- Check
character systems" whcih contains a description of a great many checksum
systems and their applicability to different identifier structures.

An understanding of checksums and their characteristics would certainly be
a lesson worth learning for anyone interested in how their information is
passed within computer systems.  it is also an introduction of computing
concepts like error correction.

cjl

[Español]

El sistema usted describe es generalmente denomina "checksum".

http://en.wikipedia.org/wiki/Checksum

http://es.wikipedia.org/wiki/Suma_de_verificaci%C3%B3n

Hay algoritmos múltiples para sumas comprobar calcular y cada tiene
características distintas.

Métodos Checksum emplean típicamente alguna forma de hashing (del simple a
lo complejo) y dependiendo del algoritmo hashing utilizado y la confección del
identificador se utilizan en (p.ej. todos dígitos, dígitos y letras),
checksums son capaces de detectar errores transposición , simple
sustituciones sola y / o sustituciones doble.

http://en.wikipedia.org/wiki/List_of_hash_functions

Checksums se ampliamente utilizado en códigos de barras aplicaciones y
transmisión datos para buscar corrupción datos. Se utilizan en todas
transacciones
bancarias y son probablemente impreso en su chequera.

La Organización Normas Internacionales publica:
ISO / IEC 7064:2003 "tecnología información - Técnicas Seguridad - Compruebe
sistemas carácter" que contiene una descripción de un sistemas checksum gran
muchos y su aplicabilidad a estructuras identificador diferente.

Una comprensión de checksums y sus características ciertamente sería una
lección pena aprender para cualquiera interesado en cómo sus información se
pasa dentro sistemas informáticos. también es una introducción de
conceptos computación
como corrección error.
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