Why does the composite check digit in the machine-readable area of ​​the modern passport not take into account all the data?

Question

Modern passports and ID cards have a machine-readable zone (MRZ) below, which contains basic identification information in what appears to be an OCR-oriented format.

The MRZ format defines the number of check digits that help detect recognition errors. For example, there is a check digit calculated by the document number, a check digit covering the date of birth, etc.

At the end there is also a “composite check digit”, which is calculated on the bottom line of the record, thereby providing a general overall integrity check.

The "top line" of the record, which contains the first and last name, however, is not covered by any check digits, which means that there is generally no way to catch errors or verify the validation.

My question is this: is there a reasonable explanation why this choice was made in the specification? Why should the specification not contain at least one check digit covering all the data in the record, which facilitates the same “machine readability” that it is aimed at? The standard is mature and widely used, therefore, it cannot be just a mistake, right?

I understand that this question is somewhat unconventional, but I have no idea where I can find the answer - suggestions are welcome along with the actual answers.

Answer 1

I was curious, and I (italics) went, although the actual documents of ICAO 9303, which determine how the machine-readable zone works, did not find any justification. The most interesting thing is that although there is a discussion about different document formats where MRZ may appear (for example, a credit card), the name string always seems to have a clear number - if any!

So, I would risk that one of the possible reasons is that the comparison from the “real name” to the machine-readable name is lost, and it seems that it is not standardized, so it depends on the transliteration rules in each country . This means that a “real name” converted to machine-readable in country A and then read in country B can legally receive something other than the original “real name”. This makes the machine readable name advisory at best; it doesn't seem like it makes sense to give him a check digit anyway. Meanwhile, the control data may be visually contrasted, as it appears to be standardized for the use of Arabic numerals.

Add to this the typical problems when trying to canonicalize names , and you may also decide that it is better to allow some freedom of action.

As a note, I realized that each of the three debit cards that I have (from the same country!) Has my name a little differently. If I had to programmatically verify that these names are the same, I would definitely make it fuzzy, and then I don’t think I would need (a lot?) About the check digit.

One more note: my obviously alien name in the country where I live always causes “interesting” situations when it comes to official documents. I do not think that I have ever managed to correctly write it here; but, fortunately, it does not matter. At the moment when any official, nurse, doctor, HR, whoever hears, I have an official identification number, they just sigh with relief and stop worrying about the correct name. (This is also a relief to me!)

So, in short: a number is necessary, and you better understand that. It is a convenience.

Answer 2

To create a key (BAC) for accessing the RFID data stored in the passport, you need to specify the document number, date of birth and validity period of the document. These numbers are very important for reading without errors. When you have calculated the correct key, you can transfer the full name, image and other data from the RFID chip with the correct spelling.