In exploring aspects of Java Card programming, I’ve been using some of my older bank cards. A question that came to mind is how does one identify the issuer of a card. I didn’t see that information explicitly encoded into the information that I could retrieve from the card. I did find the information. It is implicitly there. It can be inferred from the first few numbers of the account number that the card returns. Generally at least the first 6 numbers are needed to identify the bank. Though there are a few banks that only need 4 digits, and a few that need as much as 8 to identify. These prefixes are called Bank Identification Numbers (BIN).

There are a few reasons why someone might want to identify the card issuer. There have been promotionals from agreements between vendors and banks where the vendor gives a discount or early access to those that purchase with a card from a specific bank. There are also some banks associated with higher rates of charge-backs. One might want to take additional precautions in those instances. Card issuers also tend to be associated with a specific country. A card number could be used for establishing presence within some country.

Inferring the issuer is just a matter of finding the entry in a list of prefixes that matches the prefix of the account number in question. I’ve made two code examples available for doing this. One is written in C#, the other in C++. You can find them both in GitHub at this URL: https://github.com/j2inet/binLookup. For both code examples, I’ve included a list of prefixes and banks in embedded resources. This minimizes the number of files that must be as the executable is moved around. It also prevents a casual user from doing something that may be damaging to the data.

You can take a look at the list itself at https://github.com/j2inet/binLookup/blob/main/CS/BinLookup.net/resources/binlist.csv. I’d suggest searching in this document for the first few numbers of your own account number to see if it is in this list.

I’ve searched, but I’ve not found that there exists a unified updated list of Bank Identification Numbers. The source from which I acquired these said that he found them in the WayBackMachine that attributed the entry to an old, now deleted Wikipedia article. This information is only in furtherance of a code exmple, and is not to be relied upon for anything beyond example.

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