knovichikhin/pyiso8583

ISO8583 protocol parser that creates a regular Python dictionary describing ISO8583 data

iso8583 - a Python package for parsing ISO8583 data

iso8583 package serializes and deserializes ISO8583 data between raw bytes ISO8583 data and a regular Python dict.

iso8583 package supports custom specifications that can define:

• Field length and data encoding, such as BCD, ASCII, EBCDIC, etc.
• Field length count measured in bytes or nibbles.
• Field type, such as fixed, LLVAR, LLLVAR, etc.
• Maximum length
• Optional field description

Multiple specifications can co-exist to support ISO8583 messages for POS, ATM, file actions, and so on. Simply define a new specification dictionary. iso8583 package includes a starter specification in iso8583.specs module that can be used as a base to create own custom/proprietary specifications.

Additional information is available on Read The Docs.

Installation

iso8583 is published on PyPI as pyiso8583 and can be installed from there:

pip install pyiso8583

Encoding & Decoding

Use iso8583.decode to decode raw ISO8583 message. It returns two dictionaries: one with decoded data and one with encoded data.

>>> import pprint
>>> import iso8583
>>> from iso8583.specs import default_ascii as spec
>>> encoded_raw = b'02004000000000000000101234567890'
>>> decoded, encoded = iso8583.decode(encoded_raw, spec)
>>> pprint.pp(decoded)
{'t': '0200', 'p': '4000000000000000', '2': '1234567890'}
>>> pprint.pp(encoded)
{'t': {'len': b'', 'data': b'0200'},
 'p': {'len': b'', 'data': b'4000000000000000'},
 '2': {'len': b'10', 'data': b'1234567890'}}

Modify the decoded message to send a response back. Change message type from '0200' to '0210'. Remove field 2 (PAN). And add field 39 (Response Code).

>>> decoded['t'] = '0210'
>>> decoded.pop('2', None)
'1234567890'
>>> decoded['39'] = '05'

Use iso8583.encode to encode updated ISO8583 message. It returns a raw ISO8583 message and a dictionary with encoded data.

>>> encoded_raw, encoded = iso8583.encode(decoded, spec)
>>> encoded_raw
bytearray(b'0210000000000200000005')
>>> pprint.pp(decoded)
{'t': '0210', 'p': '0000000002000000', '39': '05'}
>>> pprint.pp(encoded)
{'t': {'len': b'', 'data': b'0210'},
 'p': {'len': b'', 'data': b'0000000002000000'},
 '39': {'len': b'', 'data': b'05'}}

Pretty Print Messages

Use iso8583.pp to pretty print ISO8583 message.

>>> import iso8583
>>> from iso8583.specs import default_ascii as spec
>>> encoded_raw = b'02004000000000000000101234567890'
>>> decoded, encoded = iso8583.decode(encoded_raw, spec)
>>> iso8583.pp(decoded, spec)
t   Message Type                  : '0200'
p   Bitmap, Primary               : '4000000000000000'
2   Primary Account Number (PAN)  : '1234567890'
>>> iso8583.pp(encoded, spec)
t   Message Type                  : b'0200'
p   Bitmap, Primary               : b'4000000000000000'
2   Primary Account Number (PAN)  : b'10' b'1234567890'

Contribute

iso8583 package is hosted on GitHub.

Feel free to fork and send contributions over.

pyiso8583's Issues

[Question] Migrating from Jpos

Hi, i was wondering, will i encounter any problem migrating from jpos to pyiso ?
I ask cuz we have some projects using jspos but due costs optimizations we're migrating to other frameworks and the first one on the list was python, and after some research i found pyiso8583 but i'm afraid i have to do tons of reworks to my logic.
Is there any thing i have to keep in mind while using pyiso ?

Signed BCD values

Does pyiso8583 support signed BCD values? eg

0xD1 0x23

being decoded as -123?

Bitmap length is 17 if max_length for primary and secondary bitmap is 16

This is my spec:

default_ascii = {
"h":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Message Header"},
"t":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Type"},
"p":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Bitmap, Primary"},
"1":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Bitmap, Secondary"},
"2":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 19,  "desc": "Primary Account Number (PAN)"},
"3":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 7,   "desc": "Processing Code"},
"4":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Transaction"},
"5":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Settlement"},
"6":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Amount, Cardholder Billing"},
"7":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transmission Date and Time"},
"8":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Amount, Cardholder Billing Fee"},
"9":   {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Conversion Rate, Settlement"},
"10":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 8,   "desc": "Conversion Rate, Cardholder Billing"},
"11":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "System Trace Audit Number"},
"12":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Time, Local Transaction"},
"13":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Local Transaction"},
"14":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Expiration"},
"15":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Settlement"},
"16":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Conversion"},
"17":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Date, Capture"},
"18":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Merchant Type or Standard Industrial Classification (SIC) or Merchant Category Code (MCC)"},
"19":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Acquiring Institution Country Code"},
"20":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "PAN Country Code"},
"21":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Forwarding Institution Country Code"},
"22":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Point-of-Service Entry Mode"},
"23":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "PAN Sequence Number / MBR"},
"24":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Network International ID (NII)"},
"25":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Point-of-Service Condition Code"},
"26":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Reason Code"},
"27":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "Authorizing ID Response Length"},
"28":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Transaction Fee"},
"29":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Settlement Fee"},
"30":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Transaction Processing Fee"},
"31":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 9,   "desc": "Amount, Settlement Processing Fee"},
"32":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Acquiring Institution ID Code"},
"33":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Forwarding Institution ID Code"},
"34":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 28,  "desc": "Primary Account Number, Extended"},
"35":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 37,  "desc": "Track 2 Data"},
"36":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 104, "desc": "Track 3 Data"},
"37":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Retrieval Reference Number"},
"38":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Authorization ID Response"},
"39":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 5,   "desc": "Response Code"},
"40":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Service Restriction Code"},
"41":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 16,   "desc": "Card Acceptor Terminal ID"},
"42":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 15,  "desc": "Card Acceptor ID Code"},
"43":  {"len_count": "nibbles", "data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 222,  "desc": "Card Acceptor Name/Location"}, # getting error here
"44":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 25,  "desc": "Additional Response Data"},
"45":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 76,  "desc": "Track 1 Data"},
"46":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - ISO"},
"47":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Additional Data - National"},
"48":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 31, "desc": "Additional Data - Private/Reference to Other Transaction"},
"49":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Transaction"},
"50":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Settlement"},
"51":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Currency Code, Cardholder Billing"},
"52":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "PIN"},
"53":  {"data_enc": "ascii", "len_enc": "b", "len_type": 0, "max_len": 48,  "desc": "Security-Related Control Information"},
"54":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12, "desc": "Adjustment Amounts"},
"55":  {"data_enc": "ascii", "len_enc": "b", "len_type": 3, "max_len": 255, "desc": "ICC data"},
"56":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved ISO"},
"57":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"58":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"59":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"60":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved National"},
"61":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 14, "desc": "Card Issuer Data"},
"62":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "External Transaction Attributes"},
"63":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16, "desc": "New Pin"},
"64":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "MAC"},
"65":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Bitmap, Extended"},
"66":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "Settlement Code"},
"67":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "Extended Payment Code"},
"68":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Receiving Institution Country Code"},
"69":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Settlement Institution Country Code"},
"70":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 3,   "desc": "Network Management Information Code"},
"71":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Number"},
"72":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4,   "desc": "Message Number, Last"},
"73":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 6,   "desc": "Date, Action"},
"74":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Credits, Number"},
"75":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Credits, Reversal Number"},
"76":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Debits, Number"},
"77":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Debits, Reversal Number"},
"78":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transfer, Number"},
"79":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Transfer, Reversal Number"},
"80":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Inquiries, Number"},
"81":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 10,  "desc": "Authorizations, Number"},
"82":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Credits, Processing Fee Amount"},
"83":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Credits, Transaction Fee Amount"},
"84":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Debits, Processing Fee Amount"},
"85":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12,  "desc": "Debits, Transaction Fee Amount"},
"86":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Credits, Amount"},
"87":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Credits, Reversal Amount"},
"88":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Debits, Amount"},
"89":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Debits, Reversal Amount"},
"90":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 42,  "desc": "Original Data Elements"},
"91":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 1,   "desc": "File Update Code"},
"92":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 2,   "desc": "File Security Code"},
"93":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 5,   "desc": "Response Indicator"},
"94":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 7,   "desc": "Service Indicator"},
"95":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 24,  "desc": "Replacement Amounts"},
"96":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "Message Security Code"},
"97":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 17,  "desc": "Amount, Net Settlement"},
"98":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 25,  "desc": "Payee"},
"99":  {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Settlement Institution ID Code"},
"100": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 11,  "desc": "Receiving Institution ID Code"},
"101": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 17,  "desc": "File Name"},
"102": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 30,  "desc": "Account ID 1 (FROM)"},
"103": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 30,  "desc": "Account ID (T0)"},
"104": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 4, "desc": "Host Net Identification"},
"105": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 25, "desc": "Account Balance Data"},
"106": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 46, "desc": "Multi Currency Data"},
"107": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 12, "desc": "Final RRN"},
"108": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Regional Listing Data/String Message"},
"109": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Multi Account Data"},
"110": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 1, "max_len": 9, "desc": "Numeric Message"},
"111": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 99, "desc": "Account Identification 2"},
"112": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"113": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"114": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 250, "desc": "Mini-Statement Data"},
"115": {"data_enc": "ascii", "len_enc": "b", "len_type": 2, "max_len": 99999, "desc": "Statement Data"},
"116": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 99999, "desc": "Billing Data"}, # Need to verify if it is ok
"117": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"118": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"119": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for National Use"},
"120": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Reserved for Private Use"},
"121": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 47, "desc": "Additional POS Data"},
"122": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 48, "desc": "3D-Secure Data"},
"123": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 999, "desc": "Miscellaneous Transaction Attributes"},
"124": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 99999, "desc": "Miscellaneous Transaction Attributes 2"},
"125": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 2, "max_len": 99999, "desc": "Administrative Transaction Data"},
"126": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 34, "desc": "Preauthorization Parameters"},
"127": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 3, "max_len": 99999, "desc": "Additional Information"},
"128": {"data_enc": "ascii", "len_enc": "ascii", "len_type": 0, "max_len": 16,  "desc": "MAC"}
}

I am getting this for primary bitmap which should be a HEX 16: b'B238641108A08000' . The HEX of the primary bitmap is 17 characters which should be 16 characters as per my spec. Could anyone please let me know, where is the issue?

Failed to decode (non-hexadecimal number found in fromhex() arg at position 0)

b"\x00H`\x00\x00\x00\x00a\x10\x00\x00\x00\x00\x02\x00p8\x00\x00\x00\xc0\x00\x00\x16\x00\x00\x001\x992 v\x990\x01\x00\x00\x00%\x00\x00\x00\x00\x11\t\x17' !\x05\t00000004100000000000002"
Traceback (most recent call last):
File "server.py", line 18, in
decoded, encoded = iso8583.decode(peticion, spec)
File "/home/userr/.local/lib/python3.8/site-packages/iso8583/decoder.py", line 114, in decode
idx = _decode_bitmaps(s, doc_dec, doc_enc, idx, spec, fields)
File "/home/user/.local/lib/python3.8/site-packages/iso8583/decoder.py", line 312, in _decode_bitmaps
raise DecodeError(
iso8583.decoder.DecodeError: Failed to decode (non-hexadecimal number found in fromhex() arg at position 0): field p pos 4

how to encode and decode 127 bitmap

Hi, I ran into this package recently, but i have a problem with my specific use case. I have a document which specifies field 127 to be a bitmap, containing other fields inside it, i.e from 127.1 to 127.25, so this field needs to be encoded and decoded as containing bitmap and data.

This is a message, but encoded with java, i need to encode the same message with python

b'\x00>0800\x828\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x00\x00\x00\x0202110526452202110526450211301000\x00\x00\x00\x00\x00\x00\x00\x0000'

so i tried to decode this message first but i get this error:

iso8583.decoder.DecodeError: Extra data after last field: field 127 pos 54

this image shows part of the specification

What do i need to do to decode the field? any ideas will help. Thanks

Install is not working

Hello,

I try to install pyiso8583 with pip install but not working, Can you help me with this wrong?
I attached a picture from error.
Thanks a lot

[suggestion] - Add length message byte to encode function

I think it would be very useful to add an optional parameter at function encode to add two bytes at the beginning of the message with the total length of it ("bigending" by the default but also parameterizable if the user needs "littleendian"). I could send you a PR with push permissions.

Best Regards.

Incorrect length of BCD encoded fields

Hello,

It seems, there is issue with calcultaion lenght for binary coded decimal (BCD) values. Encoder uses length of bytes instead of use length of nibbles.

For example, the field with value 123456 should be 06123456 in the BCD coding. 06 - length of nibbles (in other words - length of value digits). However, current implementation uses the bytes.fromhex('123456'), and after that we get length of bytes - 3 instead of 6. As result, our value 123456 will be encoded to 03123456.

Secondary bitmap is encoded in lower case

Primary bitmap is encoded in upper case.
However, secondary bitmap is encoded in lower case.

By convention secondary bitmap should be encoded in upper case.

Secondary/Extended bitmap

Hello, is there a way to define field 1 (secondary/extended bitmap) automatically according to the fields? In the same way that primary bitmap is defined. Regards!!