pyemv 1.0.0

A Python package for EMV cryptography in payment systems

PyEMV

This package provides methods for the generation of the Application Cryptograms (TC, ARQC, or AAC) generated by the ICC and the Authorisation Response Cryptogram (ARPC) generated by the issuer and verified by the ICC. In addition, this package supports secure messaging integrity and confidentiality.

Install:

pip install pyemv

PyEMV consists of the following modules:

• pyemv.ac - Application Cryptogram support for ARQC, AAC, TC, and ARPC

• pyemv.sm - Secure Messaging support for script command integrity and confidentiality. It also provides support for PIN blocks.

• pyemv.kd - Key Derivation support for ICC master keys and session keys

Key Derivation

ICC Master Key derivation method A and B:

>>> from pyemv import kd
>>> iss_mk = bytes.fromhex('0123456789ABCDEFFEDCBA9876543210')
>>> pan = b'99012345678901234'
>>> psn = b'45'
>>> icc_mk_a = kd.derive_icc_mk_a(iss_mk, pan, psn)
>>> icc_mk_a.hex().upper()
'67F8292358083E5EA7AB7FDA58D53B6B'
>>> icc_mk_b = kd.derive_icc_mk_b(iss_mk, pan, psn)
>>> icc_mk_b.hex().upper()
'985EC4FD3EDF6162E31AF1C7D0543416'

Common Session Key derivation:

>>> r = bytes.fromhex('1234567890123456')
>>> sk = kd.derive_common_sk(icc_mk_a, r)
>>> sk.hex().upper()
'29B33180E567CE38EA4CBC9D753B0E61'

Cryptogram Generation

Application Request Cryptogram generation:

>>> from pyemv import ac
>>> ac_data = bytes.fromhex('0123456789ABCDEF0123456789ABCDEF')
>>> arqc = ac.generate_ac(sk, ac_data)
>>> arqc.hex().upper()
'FA624250B008B59A'

Application Response Cryptogram generation method 1 and 2:

>>> arpc_rc = bytes.fromhex('0000')
>>> arpc = ac.generate_arpc_1(sk, arqc, arpc_rc)
>>> arpc.hex().upper()
'45D4255EEF10C920'
>>> csu = bytes.fromhex('00000000')
>>> arpc = ac.generate_arpc_2(sk, arqc, csu)
>>> arpc.hex().upper()
'CB56FA40'

Secure Messaging

Secure Messaging Integrity (MAC):

>>> from pyemv import sm
>>> sk_smi = bytes.fromhex('0123456789ABCDEFFEDCBA9876543210')
>>> command = bytes.fromhex('8424000008')
>>> mac = sm.generate_command_mac(sk_smi, command)
>>> mac.hex().upper()
'0BFFF5DF3FAA24E1'

Secure Messaging Confidentiality:

>>> pin_block = sm.format_iso9564_2_pin_block(b'9999')
>>> pin_block.hex().upper()
'249999FFFFFFFFFF'
>>> sk_smc = bytes.fromhex('0123456789ABCDEFFEDCBA9876543210')
>>> enc_data = sm.encrypt_command_data(sk_smc, pin_block,
...                                    sm.EncryptionType.EMV)
>>> enc_data.hex().upper()
'5A862D1381CCB94822CFDD706A376178'

Contribute

PyEMV is hosted on GitHub.

Feel free to fork and send contributions over.