1. UDK Derivation

MDK (Master Derivation Key, 32 hex)

[ ][ ---- ][ ---- ]

PAN

[ ]

PAN Sequence (hex, e.g. 00)

Derivation Option

UDK (result)

[ ---- ][ ---- ]

2. Session Key Derivation

UDK (32 hex)

[ ][ ---- ][ ---- ]

Session Key Method

ATC (hex, e.g. 001A)

Session Key (result)

[ ---- ][ ---- ]

3. ARQC / ARPC

Session Key (32 hex)

[ ][ ---- ][ ---- ]

Terminal Data (hex) 0 byte(s)

ICC Data (hex) Card-contributed data — AIP ‖ ATC ‖ IAD. 0 byte(s)

Break into fields (CDOL → Terminal Data, AIP/ATC/IAD → ICC Data)

Padding Method

ISO 9797-1 Method 1 — pad with 0x00

ISO 9797-1 Method 2 — pad with 0x80