I work with many institutions that use or create POS systems. Some of them have gone to using tamper resistant smart cards that debit themselves and "can't be modified by a user.". The card has some keys and some crypto stuff in 'em that only allows authorized locations (those with the keys) to credit the balance on the card. It's my understanding that the cards cost around $7 and with care have a MTBF of 18-24 months. Additionally, these systems, which are offline, execute batch jobs at night to compare the spent monies with the balance in the bank's database. If anyone has gone over their limit, the card is flagged and a "HOT" card file is downloaded to the POS locations. The POS device will not allow "HOT" cards to be used. This limits multiple spending to a 24 hour period. G.C.G. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | Geoffrey C. Grabow | "What we demand are rigidly defined | | Oyster Bay, New York | areas of doubt and uncertainty!" | | | -------------------- | | grabow_geoffrey@tandem.com | Clipper, SkipJack & Digital Telephony | | | JUST SAY NO!!! | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.3a mQCNAiz/qhsAAAEEAN4QxTfSBoeP/FCiaX0/KmCkl6BcKRa1PeoP6ZlPWydg1nOx yZAk8pIdgiGxxgiMBMsqD+SrU+Sl1Fx1AdJ14HJsBp1V6G4rBTZqvFpbNPCfrQfz K/Apg+7bBpi5Qv+sQ0TWIy38zp/laArgcdUOpE4oE2UOUBVEtYvm47K2P+i5AAUR tC9HZW9mZnJleSBDLiBHcmFib3cgPGdyYWJvd19nZW9mZnJleUB0YW5kZW0uY29t Pg== =2NWi -----END PGP PUBLIC KEY BLOCK-----