BBAN Number

A RIB (Bank Account Statement) is a document containing the information needed to identify a bank account. It includes the bank code, the sort code, the account number, and the RIB key (control key).

In France, a RIB has 23 characters:

— Bank code: 5 digits

— Sort code: 5 digits

— Account number: 11 characters (numbers and possibly letters)

— Checksum key: 2 digits between 01 and 97

The RIB corresponds to the national version of the BBAN (Basic Bank Account Number), a standardized format across Europe.

The IBAN (International Bank Account Number) is an extended version of the RIB (Bank Account Number) that uniquely identifies an account worldwide.

It incorporates the information from the RIB, preceded by a country code (two letters) and a few other control digits. dCode has a dedicated IBAN tool.

It is impossible to publicly verify that a bank account number actually corresponds to an existing account (i.e., that there is indeed a bank containing this bank account and that this account is active and has money in it): this data is subject to banking secrecy.

On the other hand, the presence of the control key allows the verification of the technical validity of a RIB.

If the key calculation fails, the bank account number is false/erroneous.

If the calculation succeeds, the bank account number is technically valid, but this does not guarantee its authenticity (a fraudster can provide a valid bank account number from a stolen/spoofed account).

The algorithm for the validation calculator checks the BBAN key via a modulo 97:

Step 1: Remove the key BBAN code.

Step 2: replace any letters by figures in the table

Step 3: Calculate the value of the result number modulo 97, then subtract the result to 97.

The checksum key is therefore 03 (the key removed previously), the BBAN is valid.

The number 97 is a prime number (the largest two-digit prime number).

Using a modulo based on a prime number effectively detects most input errors or digit permutations.