Undetectable Alternate Secret Codes
Original Publication Date: 2001-Mar-01
Included in the Prior Art Database: 2003-Jun-18
PIN codes (Personal Identification Number) are very common today. Users identify themselves to various systems with a card, in the case of ATMs (Automated Teller Machines), or with a user ID, in the case of computers. After that, the user has to proove his identity by typing his secret PIN code or password. Only then is the user authenticated. The present disclosure deals with alternate codes (PIN codes or passwords) used to silently indicate to the system that the user requires some special treatment. Codes are kept secret by the user. If a third party obtains such a code, it will obviously not be able to detect whether it is the main code or an alternate code. As an example, consider the case of a third party forcing a user to withdraw cash from an ATM machine (this is unfortunately a growing problem). The user can refuse to give out his PIN code, or enter too many wrong PIN codes so that the account ends up being locked. If instead the user cooperates, he obviously minimizes possible retaliation from the third party. On the other hand, he will have to bring evidence showing he was forced to do so, if he wants the bank to eventually cancel the transaction.