VISA¶

VISA-specific field definitions and requirements for iso8583sim.

Network Detection¶

VISA cards are detected by PAN prefix: - Starts with 4 - 13, 16, or 19 digits

from iso8583sim.core.types import detect_network, CardNetwork

network = detect_network("4111111111111111")
assert network == CardNetwork.VISA

Required Fields¶

VISA authorization requests require:

Field	Name	Format
2	PAN	LLVAR (13-19 digits)
3	Processing Code	n6
4	Amount	n12
11	STAN	n6
14	Expiration Date	n4 (YYMM)
22	POS Entry Mode	n3
24	NII	n3
25	POS Condition Code	n2

VISA-Specific Fields¶

Field 62 - VISA Private Data¶

Reserved for VISA-specific data elements:

message.fields[62] = "01" + "0123456789"  # Example format

Field 63 - VISA Additional Data¶

Additional transaction data:

Sub-element	Description
01	Network ID
02	Settlement Basis
03	Transaction ID

POS Entry Modes (Field 22)¶

Value	Description
010	Manual/Key Entry (No PIN)
011	Manual/Key Entry (PIN Entry)
051	Chip Card (No PIN)
052	Chip Card (PIN Entry)
071	Contactless (No PIN)
072	Contactless (PIN Entry)
901	Magnetic Stripe (No PIN)
902	Magnetic Stripe (PIN Entry)

Response Codes (Field 39)¶

Code	Description
00	Approved
01	Refer to Issuer
05	Do Not Honor
12	Invalid Transaction
14	Invalid Card Number
41	Lost Card - Pick Up
43	Stolen Card - Pick Up
51	Insufficient Funds
54	Expired Card
55	Incorrect PIN
61	Exceeds Withdrawal Limit
65	Activity Count Limit Exceeded
75	PIN Tries Exceeded
91	Issuer Unavailable

Example: VISA Authorization Request¶

from iso8583sim.core.types import ISO8583Message, CardNetwork
from iso8583sim.core.builder import ISO8583Builder

message = ISO8583Message(
    mti="0100",
    network=CardNetwork.VISA,
    fields={
        0: "0100",
        2: "4111111111111111",      # VISA PAN
        3: "000000",                # Purchase
        4: "000000010000",          # $100.00
        7: "1225120000",            # Dec 25, 12:00:00
        11: "123456",               # STAN
        14: "2512",                 # Exp Dec 2025
        22: "051",                  # Chip, no PIN
        24: "100",                  # NII
        25: "00",                   # Normal transaction
        41: "TERM0001",
        42: "MERCHANT123456 ",
    }
)

builder = ISO8583Builder()
raw = builder.build(message)

Example: VISA EMV Authorization¶

from iso8583sim.demo import generate_emv_auth

emv_message = generate_emv_auth(
    pan="4111111111111111",
    amount=25000,
    cryptogram="1234567890ABCDEF",
)

# Field 55 contains EMV data
print(emv_message.fields.get(55))

VISA Base I/II¶

VISA uses two processing environments:

Base I: Authorization and clearing
Base II: Settlement and reconciliation

iso8583sim focuses on Base I authorization messages.

Validation¶

VISA-specific validation:

from iso8583sim.core.validator import ISO8583Validator
from iso8583sim.core.types import CardNetwork

validator = ISO8583Validator()
message.network = CardNetwork.VISA

errors = validator.validate_message(message)
# Validates:
# - All VISA required fields present
# - PAN passes Luhn check
# - Field formats match VISA specs