MACs

iso8583sim.security.mac For testing and simulation only. Production MACs are generated inside an HSM.

Functions

`generate_mac()`

def generate_mac(
    data: str | bytes,
    key: str | bytes,
    algorithm: int = 3,
    padding: int = 1,
    length: int = 8,
) -> str

Generate an ISO 9797-1 MAC with DES based block ciphers. Algorithm 1 is a CBC-MAC with the whole key (single, double or triple length). Algorithm 3 is the retail MAC (ANSI X9.19): single DES CBC with the left key half, then decrypt with the right half and encrypt with the left half on the final block. Parameters

str | bytes

required

Data to authenticate. A str is encoded as ASCII, which is how this simulator carries ISO 8583 messages.

str | bytes

required

MAC key as bytes or hex (8, 16 or 24 bytes for algorithm 1; 16 for algorithm 3)

int

default:"3"

ISO 9797-1 MAC algorithm: 1 or 3

int

default:"1"

ISO 9797-1 padding method: 1 or 2

int

default:"8"

MAC length in bytes, 4 to 8. Truncation keeps the leftmost bytes.

str

The MAC as uppercase hex

`verify_mac()`

def verify_mac(
    data: str | bytes,
    mac: str,
    key: str | bytes,
    algorithm: int = 3,
    padding: int = 1,
) -> bool

Check a MAC. The expected length is taken from the given MAC.

`mac_field()`

def mac_field(fields: dict[int, str]) -> int

Return which field carries the MAC: 128 when the message has a secondary bitmap, else 64.

`sign_message()`

def sign_message(
    message: ISO8583Message,
    key: str | bytes,
    builder: ISO8583Builder | None = None,
    algorithm: int = 3,
    padding: int = 1,
) -> str

Build a message with its MAC in field 64 (or 128 with a secondary bitmap). Parameters

ISO8583Message

required

Message to build. Any existing MAC field is replaced.

str | bytes

required

MAC key as bytes or hex

ISO8583Builder | None

default:"None"

Builder to use (defaults to one for the message’s version)

int

default:"3"

ISO 9797-1 MAC algorithm: 1 or 3

int

default:"1"

ISO 9797-1 padding method: 1 or 2

str

The raw message with the MAC filled in

`verify_message()`

def verify_message(
    raw: str,
    key: str | bytes,
    algorithm: int = 3,
    padding: int = 1,
    version: ISO8583Version | None = None,
) -> bool

Check the MAC in field 64 or 128 of a raw message built by this simulator.

Core

Security

Wire formats

Networking

LLM

Servers

Demo

Functions

`generate_mac()`

`verify_mac()`

`mac_field()`

`sign_message()`

`verify_message()`

​Functions

​generate_mac()

​verify_mac()

​mac_field()

​sign_message()

​verify_message()

Functions

`generate_mac()`

`verify_mac()`

`mac_field()`

`sign_message()`

`verify_message()`