ISO8583 Financial transaction card originated messages Interchange message specifications is the International Organization for Standardization standard for systems that exchange electronic transactions made by cardholders using payment cards The objective of this protocol is to transmit information for payment processing through a network, usually using TCP/IP sockets. An ISO8583 message can have up to 63 or 127 fields and is processed in a linear way, that is, the message can be processed as it is being read.
Structure ISO8583 We can separate the message into 3 parts: − Message Type Identifier(MTI) − Bitmaps − Data Elements
Message Type Identifier Message Type Identifier or MTI is 4 digits numeric that describe the message type. It will explain the message function. − ISO 8583 version − Message class − Message function − Message origin
ISO 8583 version Position one of the MTI specifies the versions of the ISO 8583 standard which is being used to transmit the message.
Message class Position two of the MTI specifies the overall purpose of the message.
Message function Position three of the MTI specifies the message function which defines how the message should flow within the system.
Message origin Position four of the MTI defines the location of the message source within the payment chain.
Bitmaps Within ISO 8583, a bitmap is a field or subfield within a message which indicates which other data elements or data element subfields may be present elsewhere in a message. A message will contain at least one bitmap, called the Primary Bitmap which indicates which of Data Elements 1 to 64 are present. A secondary bitmap may also be present, generally as data element one and indicates which of data elements 65 to 128 are present.
Data elements Data elements are the individual fields carrying the transaction information. Each data element has a specified meaning and format, the standard also includes some general purpose data elements and system- or country- specific data elements Each data element is described in a standard format which defines the permitted content of the field (numeric, binary, etc.) and the field length (variable or fixed)
ISO 8583 Example Examples Message 210040300041808100000599501100000000001200 805020723006015070000000070112222ABC00000 000000010190000000530000000001 The components that form it, and the results are bitmap consists of 16 bit characters cause the first bit of the decimal 7 (0100) is ’0 ‘so identified without secondary bitmap
ISO 8583 Example The components that form it, and the results are as follows:
ISO 8583 Example Each character in the bitmap in-unpack into 4 binary characters. These elements exist in the data-elements are elements to: 2, 11, 12, 26, 32, 33, 41, 48 (Position of value “1″is read from left to the right column to unpack binary)
ISO 8583 ExampleEach position is worth ’1 ‘at the unpacked-Bitmap have data elements that correspond to components of data- elements.Data elements:05995011000000000012008050 207230060150700000000701 07 12222ABC000000000000101 90000000530000000001