Card + PIN flow
User inserts card, enters PIN. ATM builds an ISO 8583 message: card number + encrypted PIN + amount + ATM ID.
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Card + PIN flow
User inserts card, enters PIN. ATM builds an ISO 8583 message: card number + encrypted PIN + amount + ATM ID.
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Switch routes to issuer
Message routed by BIN (first 6 digits) to your bank's authorization service. In India: NPCI switch. Internationally: Visa/Mastercard.
PIN verification in HSM
Hardware Security Module verifies encrypted PIN against stored offset. PIN never leaves HSM in cleartext.
Authorization + fraud check
Bank checks balance + fraud rules (unusual location, velocity). Response: approve/decline with reason code.
Settlement is asynchronous
Cash dispensed immediately. Inter-bank money movement (T+1 batch) via clearinghouse. Interchange fees, reconciliation, disputes handled here.