Tool to check BBAN numbers. The BBAN (Basic Bank Account Number) checksum algorithm allows to check if a full bank account BBAN number is correct.
BBAN Number - dCode
Tag(s) : Checksum
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This tool checks BBAN, for IBAN numbers, dCode has a tool for that:
A BBAN (Basic Bank Account Number) is a number identifying a bank account in a country. It is composed of 10 to 30 characters, depending on countries, these characters include bank codes (including the account number) and a checksum key.
Example: In France a BBAN/RIB has 23 characters: bank code (5 digits) + counter code (5 digits) + account number (11 digits and / or letters) + RIB key (2 digits between 01 and 97).
French BBAN number : 12345 12345 0123456789A 03
It is not possible to verify that a RIB exists with certainty (that is to say, that there is indeed a bank that contains this bank account and that account is active), indeed, only banks know their account numbers and associated RIBs and this data is a banking secret. On the other hand, it is possible to check that a RIB is technically valid (that is to say that it does not contain an error in its digits / characters) thanks to the control key which is integrated into the RIB.
The calculator algorithm checks the BBAN key via a modulo 97:
Example: The bank number is: 12345 12345 0123456789A 03
Step 1: Remove the key BBAN code.
Example: The key is composed of the last 2 digits: 03. The rest of the calculation is done with 12345 12345 0123456789A 00.
Step 2: replace any letters by figures in the table
|B, K, S||2|
|C, L, T||3|
|D, M, U||4|
|E, N, V||5|
|F, O, W||6|
|G, P, X||7|
|H, Q, Y||8|
|I, R, Z||9|
Example: A=1, the BBAN becomes 12345123450123456789100
Example: $ 12345123450123456789100 \mod 97 \equiv 94 $ and $ 97 - 94 = 3 $
The checksum key is therefore 03 (the key removed previously), the BBAN is valid.
Why 97? Because it is a prime number (the largest with 2 digits) that will allow to minimize the errors.